Chofong Gilbert Nchongboh | Julius Kühn Institute, Bundesforschungsinstitut für Kulturpflanzen (original) (raw)

Papers by Chofong Gilbert Nchongboh

Research paper thumbnail of Identification and molecular characterization of a chitin-binding protein from the beet webworm, Loxostege sticticalis L

International journal of molecular sciences, Jan 22, 2014

As the first crucial barrier in the midgut of insects, the peritrophic membrane (PM) plays an imp... more As the first crucial barrier in the midgut of insects, the peritrophic membrane (PM) plays an important role in preventing external invasion. PM proteins, as the major components of the PM, determine the structure and function of this membrane. A new PM protein, named LstiCBP, from the PM of Loxostege sticticalis larvae was identified using cDNA library screening. The full cDNA of LstiCBP is 2606 bp in length and contains a 2403 bp ORF that encodes an 808-amino acid preprotein with a 15-amino acid as signal peptide. The deduced protein sequence of the cDNA contains 8 cysteine-rich chitin-binding domains (CBDs). Recombinant LstiCBP was successfully expressed in BL21 cells using recombinant plasmid DNA and showed high chitin-binding activity. LstiCBP expression was detected in the midgut at both the transcriptional and translational levels; however, the biochemical and physiological functions of LstiCBP in L. sticticalis require further investigation.

Research paper thumbnail of Participation of Multifunctional RNA in Replication, Recombination and Regulation of Endogenous Plant Pararetroviruses (EPRVs)

Frontiers in Plant Science, Jun 21, 2021

Research paper thumbnail of Agarose-resolvable InDel markers based on whole genome re-sequencing in cucumber

Scientific Reports, 2021

Insertion and Deletion (InDel) are common features in genomes and are associated with genetic var... more Insertion and Deletion (InDel) are common features in genomes and are associated with genetic variation. The whole-genome re-sequencing data from two parents (X1 and X2) of the elite cucumber (Cucumis sativus) hybrid variety Lvmei No.1 was used for genome-wide InDel polymorphisms analysis. Obtained sequence reads were mapped to the genome reference sequence of Chinese fresh market type inbred line ‘9930’ and gaps conforming to InDel were pinpointed. Further, the level of cross-parents polymorphism among five pairs of cucumber breeding parents and their corresponding hybrid varieties were used for evaluating hybrid seeds purity test efficiency of InDel markers. A panel of 48 cucumber breeding lines was utilized for PCR amplification versatility and phylogenetic analysis of these markers. In total, 10,470 candidate InDel markers were identified for X1 and X2. Among these, 385 markers with more than 30 nucleotide difference were arbitrary chosen. These markers were selected for experim...

Research paper thumbnail of Validation of some disease-resistance molecular markers associated with multiple diseases in tomato for marker-assisted selection program

ScienceAsia, 2020

Marker-assisted selection (MAS) is a tool that is widely applied in tomato resistance breeding. T... more Marker-assisted selection (MAS) is a tool that is widely applied in tomato resistance breeding. To determine the robustness of some molecular markers commonly used in MAS, extensive screening of 964 tomato lines was performed under a controlled experimental condition. Initially, the application of 36 molecular markers targeting 26 resistance genes (R genes) and 14 major diseases was evaluated. Here, we employed basic molecular biology and bioinformatics techniques for analysis where polymorphism, accuracy and clearness of amplicons constituted the selection criteria of markers. Upon initial analysis, 20 of these markers designated as efficient markers, among which 8 were considered gene-based markers and referred to as perfect markers were selected for detail evaluation. Information extrapolated from PCR result revealed 18 R genes that control 12 diseases were grouped under efficient markers. On the other hand, grouping of breeding lines based on the number of R gene harbored comprehensively revealed 62% of the lines to be void of R gene, while 38% carry different types of R genes. This provides us with an avenue to better understand new sources of resistance in the breeding lines. Conclusively, these efficient markers and their limited PCR condition can be suggested as basis of a diagnostic kit for MAS applications against 12 major tomato diseases and the identified resistant breeding lines could be conserved in order to be propagated as different sources of resistance for the development of new resistant varieties. Therefore, in areas with high vulnerability to diseases, high efficiency combination of the relevant R genes and their pyramiding into commercial tomato varieties are proposed to be implemented as a pragmatic approach.

Research paper thumbnail of Prevalence of potato viruses on potato (Solanum tuberosum L.) grown in the Western Highlands of Cameroon

Journal of Agriculture and Food Research, 2021

Research paper thumbnail of Identification of high-efficiency SSR markers for assessing watermelon genetic purity

Journal of Genetics, 2018

Research paper thumbnail of Development of a New Molecular Marker for the Resistance to Tomato Yellow Leaf Curl Virus

BioMed research international, 2018

Tomato yellow leaf curl virus (TYLCV) responsible for tomato yellow leaf curl disease (TYLCD) cau... more Tomato yellow leaf curl virus (TYLCV) responsible for tomato yellow leaf curl disease (TYLCD) causes a substantial decrease in tomato (Solanum lycopersicum L.) yield worldwide. The use of resistant variety as a sustainable management strategy has been advocated. Tremendous progress has been made in genetically characterizing the resistance genes (R gene) in tomato. Breeding tomato for TYLCV resistance has been based mostly on Ty-3 as a race-specific resistance gene by introgression originating from wild tomato species relatives. Improvement or development of a cultivar is achievable through the use of marker-assisted selection (MAS). Therefore, precise and easy use of gene-targeted markers would be of significant importance for selection in breeding programs. The present study was undertaken to develop a new marker based on Ty-3 gene sequence that can be used for MAS in TYLCV resistant tomato breeding program. The new developed marker was named ACY. The reliability and accuracy of ACY were evaluated against those of Ty-3 linked marker P6-25 through screening of commercial resistant and susceptible tomato hybrids, and genetic segregation using F2 population derived from a commercial resistant hybrid AG208. With the use of bioinformatics and DNA sequencing analysis tools, deletion of 10 nucleotides was observed in Ty-3 gene sequence for susceptible tomato variety. ACY is a co-dominant indel-based marker that produced clear and strong polymorphic band patterns for resistant plant distinguishing it from its susceptible counterpart. The obtained result correlates with 3:1 segregation ratio of single resistant dominant gene inheritance, which depicted ACY as gene-tag functional marker. This marker is currently in use for screening 968 hybrids varieties and one thousand breeding lines of tomato varieties stocked in Jiangsu Green Port Modern Agriculture Development Company (Green Port). So far, ACY has been used to identify 56 hybrids and 51 breeding lines. These newly detected breeding lines were regarded as potential source of resistance for tomato breeding. This work exploited the sequence of Ty-3 and subsequently contributed to the development of molecular marker ACY to aid phenotypic selection. We thus recommend this marker to breeders, which is suitable for marker-assisted selection in tomato.

Research paper thumbnail of Prevalence of Six Viruses in Potato Seed Tubers Produced in Informal Seed System in the North West Region of Cameroon

Cameroon Journal of Experimental Biology, 2013

Potato (Solanum tuberosum L.) is an important cash-food crop, which is widely grown in three of t... more Potato (Solanum tuberosum L.) is an important cash-food crop, which is widely grown in three of the five agro-ecological zones of Cameroon. A study was carried out to determine the prevalence of PVA, PLRV, PVM, PVS, PVX and PVY in 1175 sprouted potato seed tubers of different diameters collected from four seed stores in the North West Region of Cameroon. The study also sorts to ascertain variations in virus incidence in small, medium and large size sprouted tubers prior to planting. The DAS-ELISA method was used to test for the presence of these viruses. Results showed significant differences in the prevalence of the six viruses with PVM being the most prevalent (92%), while PLRV was least prevalent (35%) in all the four seed stores sampled. Upper-Farm store registered the highest relative prevalence (82%), with PVM detected in all the tubers while samples from Rock-Farm store showed the least relative incidence (55%) with no PLRV detected. Viruses were significantly most prevalent in small size tubers (71%) and least in large size potato tubers (63%). Our results suggest that tuber size can serve as a guide to identify healthy (virus-free) tubers. Farmers could therefore use large size potato tubers for planting.

Research paper thumbnail of Protein–protein interactions between proteins of Citrus tristeza virus isolates

Virus Genes, 2014

Citrus tristeza virus (CTV) is one of the most devastating pathogens of citrus. Its genome is org... more Citrus tristeza virus (CTV) is one of the most devastating pathogens of citrus. Its genome is organized into 12 open reading frames (ORFs), of which ten ORFs located at the 3'-terminus of the genome have multiple biological functions. The ten genes at the 3'-terminus of the genome of a severe isolate (CTV-S4) and three ORFs (CP, CPm and p20) of three other isolates (N4, S45 and HB1) were cloned into pGBKT7 and pGADT7 yeast shuttle vectors. Yeast two-hybridization (Y2H) assays results revealed a strong self-interaction for CP and p20, and a unique interaction between the CPm of CTV-S4 (severe) and CP of CTV-N4 (mild) isolates. Bimolecular fluorescence complementation also confirmed these interactions. Analysis of the deletion mutants delineated the domains of CP and p20 self-interaction. Furthermore, the domains responsible for CP and p20 self-interactions were mapped at the CP amino acids sites 41-84 and p20 amino acids sites 1-21 by Y2H. This study provided new information on CTV protein interactions which will help for further understanding the biological functions.

Research paper thumbnail of Antifungal Activities of Plant Extracts against Some Aquatic Fungi

Research paper thumbnail of Identification and characterization of Colletotrichum fructicola causing black spots on young fruits related to bitter rot of pear (Pyrus bretschneideri Rehd.) in China

Crop Protection, 2014

Mango (Mangifera indica) is widely grown across southern China, especially in the provinces of Gu... more Mango (Mangifera indica) is widely grown across southern China, especially in the provinces of Guangxi, Hainan, Yunnan, Sichuan, and Taiwan. Guangxi itself has over 86,667 ha of mango production. The purpose of this study was to identify Colletotrichum species associated with mango in different parts of Guangxi and examine their pathogenicity on leaves and fruits of mango in vitro. Diseased leaves were collected from 25 mango orchards in different areas of Guangxi province. Sixtyfive isolates were obtained from mango leaves with anthracnose symptoms, and these were further characterized based on morphology and DNA sequencing. Twenty-nine isolates from different areas were selected for sequencing and analyses of the internal transcribed spacer region, glyceraldehyde-3-phosphate dehydrogenase, partial actin, b-tubulin, and chitin synthase genomic regions. The most common fungal isolates were these three species: Colletotrichum asianum, C. fructicola, and C. siamense. C. asianum was the most common and widely distributed in Guangxi (51.7%), followed by C. fructicola (37.9%) and C. siamense (10.2%), both found in Tiandong, Tianyang, and Wuming counties. There was no evidence of geographical specialization of the different species. Pathogenicity assays showed that all isolates were pathogenic to mango leaves and fruit (cultivar Tainong). No relationship was found between origin of isolates and their virulence. This is the first description of C. asianum, C. fructicola, and C. siamense as causal agents of mango leaf anthracnose from Guangxi province, China.

Research paper thumbnail of Determination of scanned virus-free potato planting materials by positive selection and screening of tubers from seed stores in the western highlands of Cameroon

International Journal of Biological and Chemical Sciences, 2013

Positive selection for the identification of virus-free potato planting material was evaluated in... more Positive selection for the identification of virus-free potato planting material was evaluated in four locations in Cameroon. Leaves from asymptomatic plants were randomly collected, the plants marked and tubers collected four weeks later, and screened with DAS-ELISA for PLRV, PVY, PVA, PVX, PVS and PVM presence. Five viruses were prevalent in leaves while four prevalent in tubers. Potato virus M was highly prevalent in leaves and tubers while PVY was high only in leaves. Potato virus A was absent in both leaves and tubers while PVX was free only in tubers. A positive correlation was observed between virus prevalence in leaves and tubers (r=0.806). The prevalence of the six viruses in potato seed tubers from four seed stores was tested. Potato virus M was the most prevalent, while PLRV was the least. Small, medium and large tuber sizes were tested for the viruses, and infection rates decreased significantly the bigger the tuber size. Positive selection though not highly efficient can be recommended for resource-poor farmers, to control the economically important potato viruses. Tuber size can serve as a guide to identify healthy tubers, but must be combined with laboratory tests for effective use in selecting seeds for planting.

Research paper thumbnail of Prevalence of Six Viruses in Potato Seed Tubers Produced in Informal Seed System in the North West Region of Cameroon

Potato (Solanum tuberosum L.) is an important cash-food crop, which is widely grown in three of t... more Potato (Solanum tuberosum L.) is an important cash-food crop, which is widely grown in three of the five agro-ecological zones of Cameroon. A study was carried out to determine the prevalence of PVA, PLRV, PVM, PVS, PVX and PVY in 1175 sprouted potato seed tubers of different diameters collected from four seed stores in the North West Region of Cameroon. The study also sorts to ascertain variations in virus incidence in small, medium and large size sprouted tubers prior to planting. The DAS-ELISA method was used to test for the presence of these viruses. Results showed significant differences in the prevalence of the six viruses with PVM being the most prevalent (92%), while PLRV was least prevalent (35%) in all the four seed stores sampled. Upper-Farm store registered the highest relative prevalence (82%), with PVM detected in all the tubers while samples from Rock-Farm store showed the least relative incidence (55%) with no PLRV detected. Viruses were significantly most prevalent ...

Research paper thumbnail of Farmers’ Knowledge of Potato Viruses and Management Strategies in the Western Highlands of Cameroon

Open Journal of Applied Sciences, 2021

Potato (Solanum tuberosum L.), important staple food and a source of income to small-scale farmer... more Potato (Solanum tuberosum L.), important staple food and a source of income to small-scale farmers, is mostly cultivated in Cameroon in the Western Highlands. Production constraints are exerted on this crop by many pathogens including viruses responsible for considerable yield losses. This study aimed at assessing the perception of farmers on the virus diseases that can affect potatoes, and to identify the control methods adopted against them. A semi-structured survey was carried out among 230 farmers in 24 villages of the Western Highlands zone of Cameroon. Out of these farmers, 80.87% had never heard of potato viruses. Those having pre-knowledge about potato viruses were 19.13%. Among the latter, 16.52% had heard of potato viruses and transmission mode during capacity building workshops while 2.61% didn’t know about the means of transmission. Insect control is essentially chemical (100%). However, few farmers use biological methods such as intercropping (7.39%) and application of ...

Research paper thumbnail of Development of a New Molecular Marker for the Resistance to Tomato Yellow Leaf Curl Virus

Tomato yellow leaf curl virus (TYLCV) responsible for tomato yellow leaf curl disease (TYLCD) cau... more Tomato yellow leaf curl virus (TYLCV) responsible for tomato yellow leaf curl disease (TYLCD) causes a substantial decrease in tomato (Solanum lycopersicum L.) yield worldwide. The use of resistant variety as a sustainable management strategy has been advocated. Tremendous progress has been made in genetically characterizing the resistance genes (R gene) in tomato. Breeding tomato for TYLCV resistance has been based mostly on Ty-3 as a race-specific resistance gene by introgression originating from wild tomato species relatives. Improvement or development of a cultivar is achievable through the use of marker-assisted selection (MAS). Therefore, precise and easy use of gene-targeted markers would be of significant importance for selection in breeding programs. The present study was undertaken to develop a new marker based on Ty-3 gene sequence that can be used for MAS in TYLCV resistant tomato breeding program. The new developed marker was named ACY. The reliability and accuracy of A...

Research paper thumbnail of Protein-protein interactions between proteins of Citrus tristeza virus isolates

Citrus tristeza virus (CTV) is one of the most devastating pathogens of citrus. Its genome is org... more Citrus tristeza virus (CTV) is one of the most devastating pathogens of citrus. Its genome is organized into 12 open reading frames (ORFs), of which ten ORFs located at the 3 0 -terminus of the genome have multiple biological functions. The ten genes at the 3 0 -terminus of the genome of a severe isolate (CTV-S4) and three ORFs (CP, CPm and p20) of three other isolates (N4, S45 and HB1) were cloned into pGBKT7 and pGADT7 yeast shuttle vectors. Yeast two-hybridization (Y2H) assays results revealed a strong self-interaction for CP and p20, and a unique interaction between the CPm of CTV-S4 (severe) and CP of CTV-N4 (mild) isolates. Bimolecular fluorescence complementation also confirmed these interactions. Analysis of the deletion mutants delineated the domains of CP and p20 self-interaction. Furthermore, the domains responsible for CP and p20 self-interactions were mapped at the CP amino acids sites 41-84 and p20 amino acids sites 1-21 by Y2H. This study provided new information on CTV protein interactions which will help for further understanding the biological functions.

Research paper thumbnail of Prevalence of Six Viruses in Potato Seed Tubers Produced in Informal Seed System in the North West Region of Cameroon

Potato (Solanum tuberosum L.) is an important cash-food crop, which is widely grown in three of t... more Potato (Solanum tuberosum L.) is an important cash-food crop, which is widely grown in three of the five agro-ecological zones of Cameroon. A study was carried out to determine the prevalence of PVA, PLRV, PVM, PVS, PVX and PVY in 1175 sprouted potato seed tubers of different diameters collected from four seed stores in the North West Region of Cameroon. The study also sorts to ascertain variations in virus incidence in small, medium and large size sprouted tubers prior to planting. The DAS-ELISA method was used to test for the presence of these viruses. Results showed significant differences in the prevalence of the six viruses with PVM being the most prevalent (92%), while PLRV was least prevalent (35%) in all the four seed stores sampled. Upper-Farm store registered the highest relative prevalence (82%), with PVM detected in all the tubers while samples from Rock-Farm store showed the least relative incidence (55%) with no PLRV detected. Viruses were significantly most prevalent in small size tubers (71%) and least in large size potato tubers (63%). Our results suggest that tuber size can serve as a guide to identify healthy (virus-free) tubers. Farmers could therefore use large size potato tubers for planting.

Research paper thumbnail of Identification of high-efficiency SSR markers for assessing watermelon genetic purity

Genomic simple sequence repeat (SSR) markers were used to fingerprint and determine genetic simil... more Genomic simple sequence repeat (SSR) markers were used to fingerprint and determine genetic similarity (GS) of the watermelon breeding lines, as well as the purity of their hybrid derivatives. Cluster analysis and Jaccard's distance coefficients using the unweighted pair group method with arithmetic mean (UPGMA) have classified these lines into three major groups. Notwithstanding, the genetic background of these lines is narrow as revealed by the restricted GS coefficients. Fifty-five sets of SSR markers were employed in this study. Fourteen of these markers were polymorphic between the breeding lines and were used for assessing hybrid purity. Cross-checking assay validated nine SSR markers as informative SSR markers for purity detection of these hybrids. To confirm the accuracy and efficiency of these markers, their derived PCR products were further sequenced, and ClSSR09643, ClSSR18153 and ClSSR01623 were selected as high-efficiency SSR markers. Interestingly, SSR markers ClSSR09643 and ClSSR18153 were broadly applied for purity detection of more than two different hybrids, while SSR marker ClSSR01623 behaved as a specific marker for purity detection in this study. Genetic purity of six commercial watermelon hybrids was definitely evaluated using these SSR markers. Genetic purity of all tested hybrids exceeded 96% while the field purity was above 98%. Genetic purity test was an emergency for identifying off-types and selfed female in a lot of hybrid seeds. Here, we elucidated the potential of nine SSR markers including three with higher breeding selection efficiency. We recommended them to seed company for purity improvement of watermelon commercial hybrid varieties.

Research paper thumbnail of Determination of scanned virus-free potato planting materials by positive selection and screening of tubers from seed stores in the western highlands of Cameroon

Positive selection for the identification of virus-free potato planting material was evaluated in... more Positive selection for the identification of virus-free potato planting material was evaluated in four locations in Cameroon. Leaves from asymptomatic plants were randomly collected, the plants marked and tubers collected four weeks later, and screened with DAS-ELISA for PLRV, PVY, PVA, PVX, PVS and PVM presence. Five viruses were prevalent in leaves while four prevalent in tubers. Potato virus M was highly prevalent in leaves and tubers while PVY was high only in leaves. Potato virus A was absent in both leaves and tubers while PVX was free only in tubers. A positive correlation was observed between virus prevalence in leaves and tubers (r=0.806). The prevalence of the six viruses in potato seed tubers from four seed stores was tested. Potato virus M was the most prevalent, while PLRV was the least. Small, medium and large tuber sizes were tested for the viruses, and infection rates decreased significantly the bigger the tuber size. Positive selection though not highly efficient can be recommended for resource-poor farmers, to control the economically important potato viruses. Tuber size can serve as a guide to identify healthy tubers, but must be combined with laboratory tests for effective use in selecting seeds for planting.

Research paper thumbnail of Identification and molecular characterization of 16SrV group phytoplasmas with flowering cherry in China

Flowering cherry (Prunus serrulata) trees showing symptoms of excessive axillary growth, stunting... more Flowering cherry (Prunus serrulata) trees showing symptoms of excessive axillary growth, stunting, short internodes and decline were observed in Yantai City, Shandong province, China. The samples with the flowering cherry decline were designated as FcD-YT phytoplasma. Sequencing results, restriction fragment length polymorphism (RFLP) and phylogenetic analysis of sequences from the 1248-bp R16F2n ⁄ R16R2 products and partial ribosomal protein operon genes revealed the FcD-YT phytoplasma as a member of subgroup 16SrV-B, rpV-C. Two RFLP patterns were observed in recombinant colonies from the cloned 16S rDNA gene with endonucleases HpaII and MseI. To our knowledge, this is the first report of 16SrV group phytoplasma declining flowering cherry trees in China.

Research paper thumbnail of Identification and molecular characterization of a chitin-binding protein from the beet webworm, Loxostege sticticalis L

International journal of molecular sciences, Jan 22, 2014

As the first crucial barrier in the midgut of insects, the peritrophic membrane (PM) plays an imp... more As the first crucial barrier in the midgut of insects, the peritrophic membrane (PM) plays an important role in preventing external invasion. PM proteins, as the major components of the PM, determine the structure and function of this membrane. A new PM protein, named LstiCBP, from the PM of Loxostege sticticalis larvae was identified using cDNA library screening. The full cDNA of LstiCBP is 2606 bp in length and contains a 2403 bp ORF that encodes an 808-amino acid preprotein with a 15-amino acid as signal peptide. The deduced protein sequence of the cDNA contains 8 cysteine-rich chitin-binding domains (CBDs). Recombinant LstiCBP was successfully expressed in BL21 cells using recombinant plasmid DNA and showed high chitin-binding activity. LstiCBP expression was detected in the midgut at both the transcriptional and translational levels; however, the biochemical and physiological functions of LstiCBP in L. sticticalis require further investigation.

Research paper thumbnail of Participation of Multifunctional RNA in Replication, Recombination and Regulation of Endogenous Plant Pararetroviruses (EPRVs)

Frontiers in Plant Science, Jun 21, 2021

Research paper thumbnail of Agarose-resolvable InDel markers based on whole genome re-sequencing in cucumber

Scientific Reports, 2021

Insertion and Deletion (InDel) are common features in genomes and are associated with genetic var... more Insertion and Deletion (InDel) are common features in genomes and are associated with genetic variation. The whole-genome re-sequencing data from two parents (X1 and X2) of the elite cucumber (Cucumis sativus) hybrid variety Lvmei No.1 was used for genome-wide InDel polymorphisms analysis. Obtained sequence reads were mapped to the genome reference sequence of Chinese fresh market type inbred line ‘9930’ and gaps conforming to InDel were pinpointed. Further, the level of cross-parents polymorphism among five pairs of cucumber breeding parents and their corresponding hybrid varieties were used for evaluating hybrid seeds purity test efficiency of InDel markers. A panel of 48 cucumber breeding lines was utilized for PCR amplification versatility and phylogenetic analysis of these markers. In total, 10,470 candidate InDel markers were identified for X1 and X2. Among these, 385 markers with more than 30 nucleotide difference were arbitrary chosen. These markers were selected for experim...

Research paper thumbnail of Validation of some disease-resistance molecular markers associated with multiple diseases in tomato for marker-assisted selection program

ScienceAsia, 2020

Marker-assisted selection (MAS) is a tool that is widely applied in tomato resistance breeding. T... more Marker-assisted selection (MAS) is a tool that is widely applied in tomato resistance breeding. To determine the robustness of some molecular markers commonly used in MAS, extensive screening of 964 tomato lines was performed under a controlled experimental condition. Initially, the application of 36 molecular markers targeting 26 resistance genes (R genes) and 14 major diseases was evaluated. Here, we employed basic molecular biology and bioinformatics techniques for analysis where polymorphism, accuracy and clearness of amplicons constituted the selection criteria of markers. Upon initial analysis, 20 of these markers designated as efficient markers, among which 8 were considered gene-based markers and referred to as perfect markers were selected for detail evaluation. Information extrapolated from PCR result revealed 18 R genes that control 12 diseases were grouped under efficient markers. On the other hand, grouping of breeding lines based on the number of R gene harbored comprehensively revealed 62% of the lines to be void of R gene, while 38% carry different types of R genes. This provides us with an avenue to better understand new sources of resistance in the breeding lines. Conclusively, these efficient markers and their limited PCR condition can be suggested as basis of a diagnostic kit for MAS applications against 12 major tomato diseases and the identified resistant breeding lines could be conserved in order to be propagated as different sources of resistance for the development of new resistant varieties. Therefore, in areas with high vulnerability to diseases, high efficiency combination of the relevant R genes and their pyramiding into commercial tomato varieties are proposed to be implemented as a pragmatic approach.

Research paper thumbnail of Prevalence of potato viruses on potato (Solanum tuberosum L.) grown in the Western Highlands of Cameroon

Journal of Agriculture and Food Research, 2021

Research paper thumbnail of Identification of high-efficiency SSR markers for assessing watermelon genetic purity

Journal of Genetics, 2018

Research paper thumbnail of Development of a New Molecular Marker for the Resistance to Tomato Yellow Leaf Curl Virus

BioMed research international, 2018

Tomato yellow leaf curl virus (TYLCV) responsible for tomato yellow leaf curl disease (TYLCD) cau... more Tomato yellow leaf curl virus (TYLCV) responsible for tomato yellow leaf curl disease (TYLCD) causes a substantial decrease in tomato (Solanum lycopersicum L.) yield worldwide. The use of resistant variety as a sustainable management strategy has been advocated. Tremendous progress has been made in genetically characterizing the resistance genes (R gene) in tomato. Breeding tomato for TYLCV resistance has been based mostly on Ty-3 as a race-specific resistance gene by introgression originating from wild tomato species relatives. Improvement or development of a cultivar is achievable through the use of marker-assisted selection (MAS). Therefore, precise and easy use of gene-targeted markers would be of significant importance for selection in breeding programs. The present study was undertaken to develop a new marker based on Ty-3 gene sequence that can be used for MAS in TYLCV resistant tomato breeding program. The new developed marker was named ACY. The reliability and accuracy of ACY were evaluated against those of Ty-3 linked marker P6-25 through screening of commercial resistant and susceptible tomato hybrids, and genetic segregation using F2 population derived from a commercial resistant hybrid AG208. With the use of bioinformatics and DNA sequencing analysis tools, deletion of 10 nucleotides was observed in Ty-3 gene sequence for susceptible tomato variety. ACY is a co-dominant indel-based marker that produced clear and strong polymorphic band patterns for resistant plant distinguishing it from its susceptible counterpart. The obtained result correlates with 3:1 segregation ratio of single resistant dominant gene inheritance, which depicted ACY as gene-tag functional marker. This marker is currently in use for screening 968 hybrids varieties and one thousand breeding lines of tomato varieties stocked in Jiangsu Green Port Modern Agriculture Development Company (Green Port). So far, ACY has been used to identify 56 hybrids and 51 breeding lines. These newly detected breeding lines were regarded as potential source of resistance for tomato breeding. This work exploited the sequence of Ty-3 and subsequently contributed to the development of molecular marker ACY to aid phenotypic selection. We thus recommend this marker to breeders, which is suitable for marker-assisted selection in tomato.

Research paper thumbnail of Prevalence of Six Viruses in Potato Seed Tubers Produced in Informal Seed System in the North West Region of Cameroon

Cameroon Journal of Experimental Biology, 2013

Potato (Solanum tuberosum L.) is an important cash-food crop, which is widely grown in three of t... more Potato (Solanum tuberosum L.) is an important cash-food crop, which is widely grown in three of the five agro-ecological zones of Cameroon. A study was carried out to determine the prevalence of PVA, PLRV, PVM, PVS, PVX and PVY in 1175 sprouted potato seed tubers of different diameters collected from four seed stores in the North West Region of Cameroon. The study also sorts to ascertain variations in virus incidence in small, medium and large size sprouted tubers prior to planting. The DAS-ELISA method was used to test for the presence of these viruses. Results showed significant differences in the prevalence of the six viruses with PVM being the most prevalent (92%), while PLRV was least prevalent (35%) in all the four seed stores sampled. Upper-Farm store registered the highest relative prevalence (82%), with PVM detected in all the tubers while samples from Rock-Farm store showed the least relative incidence (55%) with no PLRV detected. Viruses were significantly most prevalent in small size tubers (71%) and least in large size potato tubers (63%). Our results suggest that tuber size can serve as a guide to identify healthy (virus-free) tubers. Farmers could therefore use large size potato tubers for planting.

Research paper thumbnail of Protein–protein interactions between proteins of Citrus tristeza virus isolates

Virus Genes, 2014

Citrus tristeza virus (CTV) is one of the most devastating pathogens of citrus. Its genome is org... more Citrus tristeza virus (CTV) is one of the most devastating pathogens of citrus. Its genome is organized into 12 open reading frames (ORFs), of which ten ORFs located at the 3'-terminus of the genome have multiple biological functions. The ten genes at the 3'-terminus of the genome of a severe isolate (CTV-S4) and three ORFs (CP, CPm and p20) of three other isolates (N4, S45 and HB1) were cloned into pGBKT7 and pGADT7 yeast shuttle vectors. Yeast two-hybridization (Y2H) assays results revealed a strong self-interaction for CP and p20, and a unique interaction between the CPm of CTV-S4 (severe) and CP of CTV-N4 (mild) isolates. Bimolecular fluorescence complementation also confirmed these interactions. Analysis of the deletion mutants delineated the domains of CP and p20 self-interaction. Furthermore, the domains responsible for CP and p20 self-interactions were mapped at the CP amino acids sites 41-84 and p20 amino acids sites 1-21 by Y2H. This study provided new information on CTV protein interactions which will help for further understanding the biological functions.

Research paper thumbnail of Antifungal Activities of Plant Extracts against Some Aquatic Fungi

Research paper thumbnail of Identification and characterization of Colletotrichum fructicola causing black spots on young fruits related to bitter rot of pear (Pyrus bretschneideri Rehd.) in China

Crop Protection, 2014

Mango (Mangifera indica) is widely grown across southern China, especially in the provinces of Gu... more Mango (Mangifera indica) is widely grown across southern China, especially in the provinces of Guangxi, Hainan, Yunnan, Sichuan, and Taiwan. Guangxi itself has over 86,667 ha of mango production. The purpose of this study was to identify Colletotrichum species associated with mango in different parts of Guangxi and examine their pathogenicity on leaves and fruits of mango in vitro. Diseased leaves were collected from 25 mango orchards in different areas of Guangxi province. Sixtyfive isolates were obtained from mango leaves with anthracnose symptoms, and these were further characterized based on morphology and DNA sequencing. Twenty-nine isolates from different areas were selected for sequencing and analyses of the internal transcribed spacer region, glyceraldehyde-3-phosphate dehydrogenase, partial actin, b-tubulin, and chitin synthase genomic regions. The most common fungal isolates were these three species: Colletotrichum asianum, C. fructicola, and C. siamense. C. asianum was the most common and widely distributed in Guangxi (51.7%), followed by C. fructicola (37.9%) and C. siamense (10.2%), both found in Tiandong, Tianyang, and Wuming counties. There was no evidence of geographical specialization of the different species. Pathogenicity assays showed that all isolates were pathogenic to mango leaves and fruit (cultivar Tainong). No relationship was found between origin of isolates and their virulence. This is the first description of C. asianum, C. fructicola, and C. siamense as causal agents of mango leaf anthracnose from Guangxi province, China.

Research paper thumbnail of Determination of scanned virus-free potato planting materials by positive selection and screening of tubers from seed stores in the western highlands of Cameroon

International Journal of Biological and Chemical Sciences, 2013

Positive selection for the identification of virus-free potato planting material was evaluated in... more Positive selection for the identification of virus-free potato planting material was evaluated in four locations in Cameroon. Leaves from asymptomatic plants were randomly collected, the plants marked and tubers collected four weeks later, and screened with DAS-ELISA for PLRV, PVY, PVA, PVX, PVS and PVM presence. Five viruses were prevalent in leaves while four prevalent in tubers. Potato virus M was highly prevalent in leaves and tubers while PVY was high only in leaves. Potato virus A was absent in both leaves and tubers while PVX was free only in tubers. A positive correlation was observed between virus prevalence in leaves and tubers (r=0.806). The prevalence of the six viruses in potato seed tubers from four seed stores was tested. Potato virus M was the most prevalent, while PLRV was the least. Small, medium and large tuber sizes were tested for the viruses, and infection rates decreased significantly the bigger the tuber size. Positive selection though not highly efficient can be recommended for resource-poor farmers, to control the economically important potato viruses. Tuber size can serve as a guide to identify healthy tubers, but must be combined with laboratory tests for effective use in selecting seeds for planting.

Research paper thumbnail of Prevalence of Six Viruses in Potato Seed Tubers Produced in Informal Seed System in the North West Region of Cameroon

Potato (Solanum tuberosum L.) is an important cash-food crop, which is widely grown in three of t... more Potato (Solanum tuberosum L.) is an important cash-food crop, which is widely grown in three of the five agro-ecological zones of Cameroon. A study was carried out to determine the prevalence of PVA, PLRV, PVM, PVS, PVX and PVY in 1175 sprouted potato seed tubers of different diameters collected from four seed stores in the North West Region of Cameroon. The study also sorts to ascertain variations in virus incidence in small, medium and large size sprouted tubers prior to planting. The DAS-ELISA method was used to test for the presence of these viruses. Results showed significant differences in the prevalence of the six viruses with PVM being the most prevalent (92%), while PLRV was least prevalent (35%) in all the four seed stores sampled. Upper-Farm store registered the highest relative prevalence (82%), with PVM detected in all the tubers while samples from Rock-Farm store showed the least relative incidence (55%) with no PLRV detected. Viruses were significantly most prevalent ...

Research paper thumbnail of Farmers’ Knowledge of Potato Viruses and Management Strategies in the Western Highlands of Cameroon

Open Journal of Applied Sciences, 2021

Potato (Solanum tuberosum L.), important staple food and a source of income to small-scale farmer... more Potato (Solanum tuberosum L.), important staple food and a source of income to small-scale farmers, is mostly cultivated in Cameroon in the Western Highlands. Production constraints are exerted on this crop by many pathogens including viruses responsible for considerable yield losses. This study aimed at assessing the perception of farmers on the virus diseases that can affect potatoes, and to identify the control methods adopted against them. A semi-structured survey was carried out among 230 farmers in 24 villages of the Western Highlands zone of Cameroon. Out of these farmers, 80.87% had never heard of potato viruses. Those having pre-knowledge about potato viruses were 19.13%. Among the latter, 16.52% had heard of potato viruses and transmission mode during capacity building workshops while 2.61% didn’t know about the means of transmission. Insect control is essentially chemical (100%). However, few farmers use biological methods such as intercropping (7.39%) and application of ...

Research paper thumbnail of Development of a New Molecular Marker for the Resistance to Tomato Yellow Leaf Curl Virus

Tomato yellow leaf curl virus (TYLCV) responsible for tomato yellow leaf curl disease (TYLCD) cau... more Tomato yellow leaf curl virus (TYLCV) responsible for tomato yellow leaf curl disease (TYLCD) causes a substantial decrease in tomato (Solanum lycopersicum L.) yield worldwide. The use of resistant variety as a sustainable management strategy has been advocated. Tremendous progress has been made in genetically characterizing the resistance genes (R gene) in tomato. Breeding tomato for TYLCV resistance has been based mostly on Ty-3 as a race-specific resistance gene by introgression originating from wild tomato species relatives. Improvement or development of a cultivar is achievable through the use of marker-assisted selection (MAS). Therefore, precise and easy use of gene-targeted markers would be of significant importance for selection in breeding programs. The present study was undertaken to develop a new marker based on Ty-3 gene sequence that can be used for MAS in TYLCV resistant tomato breeding program. The new developed marker was named ACY. The reliability and accuracy of A...

Research paper thumbnail of Protein-protein interactions between proteins of Citrus tristeza virus isolates

Citrus tristeza virus (CTV) is one of the most devastating pathogens of citrus. Its genome is org... more Citrus tristeza virus (CTV) is one of the most devastating pathogens of citrus. Its genome is organized into 12 open reading frames (ORFs), of which ten ORFs located at the 3 0 -terminus of the genome have multiple biological functions. The ten genes at the 3 0 -terminus of the genome of a severe isolate (CTV-S4) and three ORFs (CP, CPm and p20) of three other isolates (N4, S45 and HB1) were cloned into pGBKT7 and pGADT7 yeast shuttle vectors. Yeast two-hybridization (Y2H) assays results revealed a strong self-interaction for CP and p20, and a unique interaction between the CPm of CTV-S4 (severe) and CP of CTV-N4 (mild) isolates. Bimolecular fluorescence complementation also confirmed these interactions. Analysis of the deletion mutants delineated the domains of CP and p20 self-interaction. Furthermore, the domains responsible for CP and p20 self-interactions were mapped at the CP amino acids sites 41-84 and p20 amino acids sites 1-21 by Y2H. This study provided new information on CTV protein interactions which will help for further understanding the biological functions.

Research paper thumbnail of Prevalence of Six Viruses in Potato Seed Tubers Produced in Informal Seed System in the North West Region of Cameroon

Potato (Solanum tuberosum L.) is an important cash-food crop, which is widely grown in three of t... more Potato (Solanum tuberosum L.) is an important cash-food crop, which is widely grown in three of the five agro-ecological zones of Cameroon. A study was carried out to determine the prevalence of PVA, PLRV, PVM, PVS, PVX and PVY in 1175 sprouted potato seed tubers of different diameters collected from four seed stores in the North West Region of Cameroon. The study also sorts to ascertain variations in virus incidence in small, medium and large size sprouted tubers prior to planting. The DAS-ELISA method was used to test for the presence of these viruses. Results showed significant differences in the prevalence of the six viruses with PVM being the most prevalent (92%), while PLRV was least prevalent (35%) in all the four seed stores sampled. Upper-Farm store registered the highest relative prevalence (82%), with PVM detected in all the tubers while samples from Rock-Farm store showed the least relative incidence (55%) with no PLRV detected. Viruses were significantly most prevalent in small size tubers (71%) and least in large size potato tubers (63%). Our results suggest that tuber size can serve as a guide to identify healthy (virus-free) tubers. Farmers could therefore use large size potato tubers for planting.

Research paper thumbnail of Identification of high-efficiency SSR markers for assessing watermelon genetic purity

Genomic simple sequence repeat (SSR) markers were used to fingerprint and determine genetic simil... more Genomic simple sequence repeat (SSR) markers were used to fingerprint and determine genetic similarity (GS) of the watermelon breeding lines, as well as the purity of their hybrid derivatives. Cluster analysis and Jaccard's distance coefficients using the unweighted pair group method with arithmetic mean (UPGMA) have classified these lines into three major groups. Notwithstanding, the genetic background of these lines is narrow as revealed by the restricted GS coefficients. Fifty-five sets of SSR markers were employed in this study. Fourteen of these markers were polymorphic between the breeding lines and were used for assessing hybrid purity. Cross-checking assay validated nine SSR markers as informative SSR markers for purity detection of these hybrids. To confirm the accuracy and efficiency of these markers, their derived PCR products were further sequenced, and ClSSR09643, ClSSR18153 and ClSSR01623 were selected as high-efficiency SSR markers. Interestingly, SSR markers ClSSR09643 and ClSSR18153 were broadly applied for purity detection of more than two different hybrids, while SSR marker ClSSR01623 behaved as a specific marker for purity detection in this study. Genetic purity of six commercial watermelon hybrids was definitely evaluated using these SSR markers. Genetic purity of all tested hybrids exceeded 96% while the field purity was above 98%. Genetic purity test was an emergency for identifying off-types and selfed female in a lot of hybrid seeds. Here, we elucidated the potential of nine SSR markers including three with higher breeding selection efficiency. We recommended them to seed company for purity improvement of watermelon commercial hybrid varieties.

Research paper thumbnail of Determination of scanned virus-free potato planting materials by positive selection and screening of tubers from seed stores in the western highlands of Cameroon

Positive selection for the identification of virus-free potato planting material was evaluated in... more Positive selection for the identification of virus-free potato planting material was evaluated in four locations in Cameroon. Leaves from asymptomatic plants were randomly collected, the plants marked and tubers collected four weeks later, and screened with DAS-ELISA for PLRV, PVY, PVA, PVX, PVS and PVM presence. Five viruses were prevalent in leaves while four prevalent in tubers. Potato virus M was highly prevalent in leaves and tubers while PVY was high only in leaves. Potato virus A was absent in both leaves and tubers while PVX was free only in tubers. A positive correlation was observed between virus prevalence in leaves and tubers (r=0.806). The prevalence of the six viruses in potato seed tubers from four seed stores was tested. Potato virus M was the most prevalent, while PLRV was the least. Small, medium and large tuber sizes were tested for the viruses, and infection rates decreased significantly the bigger the tuber size. Positive selection though not highly efficient can be recommended for resource-poor farmers, to control the economically important potato viruses. Tuber size can serve as a guide to identify healthy tubers, but must be combined with laboratory tests for effective use in selecting seeds for planting.

Research paper thumbnail of Identification and molecular characterization of 16SrV group phytoplasmas with flowering cherry in China

Flowering cherry (Prunus serrulata) trees showing symptoms of excessive axillary growth, stunting... more Flowering cherry (Prunus serrulata) trees showing symptoms of excessive axillary growth, stunting, short internodes and decline were observed in Yantai City, Shandong province, China. The samples with the flowering cherry decline were designated as FcD-YT phytoplasma. Sequencing results, restriction fragment length polymorphism (RFLP) and phylogenetic analysis of sequences from the 1248-bp R16F2n ⁄ R16R2 products and partial ribosomal protein operon genes revealed the FcD-YT phytoplasma as a member of subgroup 16SrV-B, rpV-C. Two RFLP patterns were observed in recombinant colonies from the cloned 16S rDNA gene with endonucleases HpaII and MseI. To our knowledge, this is the first report of 16SrV group phytoplasma declining flowering cherry trees in China.