M. Pillay - Academia.edu (original) (raw)
Papers by M. Pillay
Genetics, Genomics, and Breeding of Bananas, 2012
Genome analysis of multicellular organisms reveal a large number of genes for which no function i... more Genome analysis of multicellular organisms reveal a large number of genes for which no function is known or can be predicted. Many genetic tools are now available for investigating gene function. In general they are divided into two broad categories-forward and reverse genetics. This chapter reviews some of the techniques for gene functional analysis with special emphasis on insertional mutagenesis, targeted gene disruption by homologous recombination, RNA interference, virusinduced gene silencing (VIGS) technology, and Targeting Induced Local Lesions IN Genomes (TILLING). In addition progress in some areas of transcriptomics research in Musa is reviewed. Insertional mutagenesis has been widely used for cloning genes, promoters, enhancers and other regulatory sequences in the model plant Arabidopsis. Insertional mutagenesis provides a direct route to determining function. Most other approaches are correlative and do not necessarily prove a causal relationship between gene sequence and function. Gene targeting by homologous recombination, although cumbersome, is now feasible in rice. RNA interference (RNAi) is based on sequence-specific RNA degradation that follows the formation of double-stranded RNA (dsRNA) homologous in sequence to the targeted gene. RNAi
Banana production in the East African region is constrained by a variety of pests and diseases. H... more Banana production in the East African region is constrained by a variety of pests and diseases. Host plant resistance is the most convenient and effective intervention to circumvent these constraints in banana production. However, male fertility is a major limitation in the genetic improvement of bananas. Pollen quantity and quality are the key attributes in selecting male parents for successful banana crosses. Pollen was collected from 22 candidate diploid banana hybrids and 6 diploid genotypes previously, successfully used in breeding programs. It was examined for pollen quantity, staining with Iodine Potassium Iodide (I 2 KI, Lugol stain), and germination frequency on a nectar-water medium. The traits under examination varied significantly (P<0.05) among diploid banana hybrids. I 2 KI-stained pollen frequency ranged between 12.96% for hybrid ‘12506S-1’ to 100% for ‘3162K-1’, while pollen tube germination frequency ranged from 1.67% on ‘2858K-5’ to 95.66% on ‘Calcutta 4’. Relat...
Poor reproductive development in yams (Dioscorea spp.) has often been attributed to the polyploid... more Poor reproductive development in yams (Dioscorea spp.) has often been attributed to the polyploid nature of the crop. In this study, flow cytometry was used to determine the ploidy level of 53 accessions of Dioscorea alata, mostly from West African countries, Chad and Puerto Rico. Nuclei were isolated from young leaf material and stained with DAPI (4,6-diamidino-2-phenylindole). The nuclear genome size (2C) was measured as an indicator of the ploidy level. Dioscorea rotundata genotypes with known ploidy levels were used as standards. The results showed that the majority of plants were hexaploid (84.9%) with a smaller percentage of tetraploids (15.1%). A higher number of male plants were hexaploid than tetraploids. This is at variance with earlier findings, which reported that hexaploid male plants are rare. Higher ploidy levels were not directly related to sparse or erratic flowering as previously reported as profuse flowering occurred in some male hexaploid accessions. These findings have important implications for yam breeding in relation to yam genetic resources.
... of Tropical Agriculture, Onne station, Nigeria (Table 1). DNA extraction and AFLP procedure A... more ... of Tropical Agriculture, Onne station, Nigeria (Table 1). DNA extraction and AFLP procedure About 10 g of leaf tissues per sample, collected from the field in liquid nitrogen, were ground with a mortar and pestle. DNA extraction, AFLP procedure and data analysis were as ...
TAG Theoretical and Applied Genetics, 2002
Genetic diversity and relationships were assessed in 28 accessions of Musa acuminata (AA) Colla a... more Genetic diversity and relationships were assessed in 28 accessions of Musa acuminata (AA) Colla and Musa balbisiana (BB) Colla, and some of their natural hybrids, using the amplified fragment length polymorphisms (AFLP) technique. Fifteen AFLP +3 primer pairs produced 527 polymorphic bands among the accessions. Neighbor-joining and principal co-ordinate (PCO) analyses using Jaccard's similarity coefficient produced four major clusters that closely corresponded with the genome composition of the accessions (AA, BB, AAB and ABB). The AFLP data distinguished between the wild diploid accessions and suggested new subspecies relationships in the M. acuminata complex that are different from those based on morphological data. The data suggested that there are three subspecies within the M. acuminata complex (ssp. burmannica Simmonds, malaccensis Simmonds, and microcarpa Simmonds). 'Tjau Lagada' (ssp. microcarpa), 'Truncata' [ssp truncata (Ridl.) Shepherd] and 'SF247' [ssp. banksii (F.Muell) Simmonds] clustered very closely with 'Gros Michel' and 'Km 5', indicating that more than one M. acuminata subspecies may be involved in the origin of triploid AAA bananas. 'Calcutta 4' (ssp. burmannicoides De Langhe & Devreux) and 'Long Tavoy' (ssp. burmannica) were closely related and could be together in the same subspecies. This study also showed that there is much more genetic diversity within M. balbisiana that was split into two groups: (1) 'I-63' and 'HND' and (2) 'Los Banos', 'MPL' (Montpellier), '10852', 'Singapuri', 'Etikehel', and 'Butohan 1' as the other.
TAG Theoretical and Applied Genetics, 2003
The objective of this study was to construct a molecular phylogeny of the genus Musa using restri... more The objective of this study was to construct a molecular phylogeny of the genus Musa using restriction-site polymorphisms of the chloroplast (cpDNA) and mitochondrial DNA (mtDNA). Six cpDNA and two mtDNA sequences were amplified individually in polymerase chain reaction (PCR) experiments in 13 species representing the four sections of Musa. Ensete ventricosum (W.) Ch. was used as the outgroup. The amplified products were digested with ten restriction endonucleases. A total of 79 restriction-site changes were scored in the sample. Wagner parsimony using the branch and bound option defined two lines of evolution in Musa. One lineage comprised species of the sections Australimusa and Callimusa which have a basic number of x = 10 chromosomes, while most species of sections Eumusa and Rhodochlamys ( x = 11) formed the other lineage. Musa laterita Cheesman ( Rhodochlamys) had identical organellar genome patterns as some subspecies of the Musa acuminata Colla complex. The progenitors of the cultivated bananas, M. acuminata and Musa balbisiana Colla, were evolutionarily distinct from each other. Musa balbisiana occupied a basal position in the cladogram indicating an evolutionarily primitive status. The close phylogenetic relationship between M. laterita and M. acuminata suggests that species of the section Rhodochlamys may constitute a secondary genepool for the improvement of cultivated bananas.
TAG Theoretical and Applied Genetics, 2003
Fifteen AFLP primer pairs (EcoRI+3 and MseI+3) and 60 10-mer RAPD primers were used to detect pol... more Fifteen AFLP primer pairs (EcoRI+3 and MseI+3) and 60 10-mer RAPD primers were used to detect polymorphisms and assess genetic relationships in a sample of 25 plantains from diverse parts of Western and Central Africa. The discriminatory power of the AFLP technique was greater than that of the RAPD technique, since the former produced markers with greater polymorphic information content (PIC) than the latter. Hence, AFLP analysis appeared to be a more-powerful approach for identifying genetic differences among plantain accessions. In this regard, significant genetic diversity within the plantains was shown by the unweighted pair-group method of arithmetic averages (UPGMA) and the multidimensional principal coordinate (PCO) analyses. The AFLP-derived clusters indicated closer relationships between similar inflorescence types than the RAPD-derived clusters. A small group of cultivars from Cameroon were separated from the bulk of other plantains, suggesting that Cameroon may harbour accessions with useful or rare genes for widening the genetic base of breeding populations derived from the plantains. A greater effort should be directed at collecting and characterizing plantain cultivars from Cameroon.
Theoretical and Applied Genetics, 1990
Chloroplast DNA (cpDNA) restriction endonuclease patterns are used to examine phylogenetic relati... more Chloroplast DNA (cpDNA) restriction endonuclease patterns are used to examine phylogenetic relationships between Bromus subgenera Festucaria and Ceratochloa. Festucaria is considered monophyletic based on the L genome, while Ceratochloa encompasses two species complexes: the B. catharticus complex, which evolved by combining three different genomes, and the B. carinatus complex, which is thought to have originated from hybridization between polyploid species of B. catharticus and diploid members of Festucaria. All species of subgenus Ceratochloa (hexaploids and octoploids) were identical in chloroplast DNA sequences. Similarly, polyploid species of subgenus Festucaria, except for B. auleticus, were identical in cpDNA sequences. In contrast, diploid species of subgenus Festucaria showed various degrees of nucleotide sequence divergence. Species of subgenus Ceratochloa appeared monophyletic and phylogenetically closely related to the diploid B. anomalus and B. auleticus of subgenus Festucaria. The remaining diploid and polyploid species of subgenus Festucaria appeared in a distinct grouping. The study suggests that the B. catharticus complex must have been the maternal parent in the proposed hybrid origin of B. carinatus complex. Although there is no direct evidence for the paternal parent of the latter complex, the cpDNA study shows the complex to be phylogenetically very related to the diploid B. anomalus of subgenus Festucaria.
Theoretical and Applied Genetics, 1996
Random amplified polymorphic DNA (RAPD) marker-based analysis was carried out to study the extent... more Random amplified polymorphic DNA (RAPD) marker-based analysis was carried out to study the extent of genetic polymorphism between populations of the two endangered Himalayan poppy species, Meconopsis paniculata and M. Simplicifolia. Of the 90 primers tested, 38 revealed marked inter-species genetic polymorphism between individuals of the two species from geographically isolated populations. However, intra-species genetic homogeneity was also evident with respect to a number of primers both within and between populations. A comprehensive analysis incorporating data from RAPDs, DNA fingerprinting and isozyme pattern was carried out and, based on the presence or absence of bands, three matrices of similarity indices were estimated. These matrices were subsequently utilized in cluster analysis. In order to compare the three clusters generated using these three different marker systems, a Mantel matrix-correspondence test was carried out on the basis of comparisons of co-phenetic values. The overall representation of relationships by cluster analysis was similar for all three marker systems and this was substantiated by high correlations among the three analyses revealed by the Mantel matrix-correspondence test. Our results point to very low or absence of, genetic polymorphism in M. paniculata and M. simplicifolia, and are in broad agreement with our previous observations on genetic diversity of Meconopsis species which point to a genetic basis for the possible extinction of this economically important genus.
Theoretical and Applied Genetics, 1996
Genetic variation was assessed among cultivated and wild hop, Humulus lupulus, by restriction fra... more Genetic variation was assessed among cultivated and wild hop, Humulus lupulus, by restriction fragment length polymorphisms (RFLPs) of the ribosomal RNA genes (rDNA). Two rDNA length variants of 10.3 and 9.3 kbp represented by three phenotypes designated A, B and C were detected with XhoI. Restriction-site mapping showed that hop rDNA is structurally similar to those of most higher plants. A high level of homogeneity existed in rDNA repeat lengths among the diverse hop genotypes. Generally, phenotype A was predominant in wild and cultivated European and Asian genotypes; phenotype B in North American cultivars; while phenotype C was present only in native North American hop, providing a potential molecular marker for the identification of this germ plasm. The rDNA data provided genetic evidence for the separation of native and cultivated American genotypes and supports the hypothesis that North American hop cultivars are of hybrid origin from European and native American genotypes. The segregation of rDNA phenotypes in four F1 families suggests that a single locus with two co-dominant alleles controls genetic variability for rDNA variants in hop.
Plant Systematics and Evolution, 2006
The structural organization of the nuclear ribosomal DNA (rDNA) of Humulus lupulus, H. japonicus ... more The structural organization of the nuclear ribosomal DNA (rDNA) of Humulus lupulus, H. japonicus and Cannabis sativa was determined by restriction site mapping. A high degree of DNA sequence similarity was evident in the coding regions of the rDNA repeats of the taxa and supports the placement of Cannabis and Humulus in one family, Cannabaceae. However, the presence of a BstEII site, an additional SacI site, absence of the SpeI site and positional differences of the SspI sites in the 25 S gene distinguished H. japonicus from H. lupulus. Humulus lupulus has an additional EcoRV site in the IGS region. A XhoI site in the 18S region of C. sativa distinguishes it from the two hop species. The diagnostic differences in the IGS of C. sativa include the EcoRI, HindIII and XhoI sites. These sites were not detected in the IGS of the two hop species.
Plant Breeding, 2005
... EA Ogundiwin 1,2 , G. Thottappilly1 , ME Aken'Ova3 , M. Pillay1 and CA Fatokun1,4,5 ... more ... EA Ogundiwin 1,2 , G. Thottappilly1 , ME Aken'Ova3 , M. Pillay1 and CA Fatokun1,4,5 1International Institute of Tropical Agriculture, PMB ... There is however a strong crossing barrier between cowpea and V. vexillata (Evans 1976, Barone and Ng 1990, Fatokun 2002) and this ...
Journal of New Seeds, 2009
Genetic improvement of bananas is hampered by male and female sterility in most of the cultivated... more Genetic improvement of bananas is hampered by male and female sterility in most of the cultivated varieties. In addition, the triploid status of the edible varieties results in very low seed set during artificial hybridizations. The objective of this study was to determine the optimal periods in the year for seed set in East African Highland banana hybrids by examining
Journal of Crop Improvement, 2007
Abstract This study investigates the economic impact of banana Xanthomonas wilt (bxw) and drought... more Abstract This study investigates the economic impact of banana Xanthomonas wilt (bxw) and drought on banana production in Uganda. The objective of this research is to determine the benefits of targeted research to avoid economic losses. In the worst-case scenarios, ...
Genome, 2000
Plantains and bananas (Musa spp. sect. eumusa) originated from intra-and interspecific hybridizat... more Plantains and bananas (Musa spp. sect. eumusa) originated from intra-and interspecific hybridization between two wild diploid species, M. acuminata Colla. and M. balbisiana Colla., which contributed the A and B genomes, respectively. Polyploidy and hybridization have given rise to a number of diploid, triploid, and tetraploid clones with different permutations of the A and B genomes. Thus, dessert and highland bananas are classified mainly as AAA, plantains are AAB, and cooking bananas are ABB. Classification of Musa into genomic groups has been based on morphological characteristics. This study aimed to identify RAPD (random amplified polymorphic DNA) markers for the A and B genomes. Eighty 10-mer Operon primers were used to amplify DNA from M. acuminata subsp. burmannicoides clone 'Calcutta 4' (AA genomes) and M. balbisiana clone 'Honduras' (BB genomes). Three primers (A17, A18, and D10) that produced unique genome-specific fragments in the two species were identified. These primers were tested in a sample of 40 genotypes representing various genome combinations. The RAPD markers were able to elucidate the genome composition of all the genotypes. The results showed that RAPD analysis can provide a quick and reliable system for genome identification in Musa that could facilitate genome characterization and manipulations in breeding lines.
Genome, 1997
Variation in the ribosomal RNA genes (rDNA) was examined to assess the genetic variability among ... more Variation in the ribosomal RNA genes (rDNA) was examined to assess the genetic variability among 314 plants representing 28 accessions of Eragrostis tef, an important food crop. A restriction site map was constructed for the species by localization of the BamHI, BglII, DraI, EcoRI, EcoRV, NdeI, SacI, SpeI, XbaI, and XhoI sites. A comparison of this map with those of other grasses showed conservation of sites, especially in the coding region. However, a unique EcoRI site combined with a BamHI site in the 18S region may be of diagnostic value for the species. A BamHI fragment that spans the intergenic spacer was used as an indicator of length variation of rDNA repeat units. rDNA repeat units in E. tef ranged in size from 8.4 to 11.07 kbp. Considerable size variation of rDNA repeats was present among accessions, between individual plants within some accessions, and within single plants. A total of 19 spacer length (sl) phenotypes was observed in 16 accessions in which 11-42 plants were analyzed. A single restriction site polymorphism was detected in PI442115 that was also distinguished by having a single sl variant. Variation in the rRNA genes is a useful indicator of genetic diversity in E. tef germplasm.
Banana Breeding and …, 2011
... Vuylsteke, 1995). This makes crossbreeding of plantain and banana difficult. Nonetheless, sev... more ... Vuylsteke, 1995). This makes crossbreeding of plantain and banana difficult. Nonetheless, several triploid plan-tain and banana cultivars produce seeds after hand pollination with diploid parents (Ssebuliba et al., 2006). Axenic in ...
Crop Science, 1999
protection and (ii) early detection of agronomic and economic traits as an aid to marker assisted... more protection and (ii) early detection of agronomic and economic traits as an aid to marker assisted selection. Variation in the ribosomal RNA genes (rDNA) and amplified Ribosomal DNA (rDNA) is a well-characterized fragment length polymorphism (AFLP) markers has been used to establish the extent of genetic diversity and relatedness in plants. The multi-gene family in plants which is organized in tandem utility of these methods to detect inter- and intra-specific variation repeats. Each repeat contains DNA sequences coding in cotton (Gossypium spp.) has not been reported and could be useful for the 18S, 5.8S, and 25S ribosomal RNA, and an in- in cultivar identification and in marker assisted selection. The objec- tergenic region generally called the intergenic spacer tives of this study were to: (i) determine the molecular organization region or IGS (Rogers and Bendich, 1987). The 5.8S of the rDNA genes by restriction enzyme mapping and (ii) assess the coding region separates the 18S and 25S regions and is level of AFLPs in Old and New World species of cotton. A restriction bordered by two internal spacer regions referred to as site map of the rDNA gene structure of G. hirsutum L. cv. TM1 ITS1 and ITS2. Molecular studies of variability in rDNA was constructed from DNA digested with 12 restriction enzymes and show that the coding region is highly conserved while hybridized to heterologous probes. Four EcoRI-MseI primer-pair the spacer region is highly variable in sequence and combinations were used for the AFLP analysis. The rDNA gene structure in cotton was found to be similar to that of most higher length. Variation patterns in rDNA have been used : (i) plants. The rDNA repeat size was 9.4 kbp in G. hirsutum and to characterize genetic diversity in plants, (ii) to assess G. barbadense L., and 9.6 and 9.8 kbp in G. arboreum L. and G. changes in the genetic composition of breeding popula- herbaceum L., respectively. No intraspecific polymorphism was de- tions, (iii) to determine phylogenetic relationships at tected in the spacer. The presence of two SspI sites in G. arboreum different levels of the taxonomic hierarchy, and (iv) as and G. herbaceum and a single site in G. hirsutum and G. barbadense important genetic markers. separated Old and New World cottons. The AFLP method produced AFLP is polymerase chain reaction (PCR) based a 10-fold increase in the number of DNA bands per plant, compared marker technology that involves three essential steps: with random amplified polymorphic DNA (RAPD) methods. The (i) digestion of genomic DNA with two restriction en-
Euphytica, 2001
The ploidy levels of the twenty-two yam (Dioscorea cayenensis-D. rotundata complex) cultivars wit... more The ploidy levels of the twenty-two yam (Dioscorea cayenensis-D. rotundata complex) cultivars within germplasm Cameroon Guinea yam were determined by flow cytometry. Three different ploidy levels (4x, 6x, 8x) were detected within the samples analysed. Fifteen cultivars were tetraploids, five were hexaploids, and two were octoploids. The cultivar group EKOTO showed a high level of ploidy variation with tetraploid, hexaploid and octoploid cultivars. The hexaploid nature of cultivars Dobnawo and Bilougnou supported the hypothesis that they are hybrids between cultivars of the EKOTO group and either the KPE or BAKOKAE groups.
Genetics, Genomics, and Breeding of Bananas, 2012
Genome analysis of multicellular organisms reveal a large number of genes for which no function i... more Genome analysis of multicellular organisms reveal a large number of genes for which no function is known or can be predicted. Many genetic tools are now available for investigating gene function. In general they are divided into two broad categories-forward and reverse genetics. This chapter reviews some of the techniques for gene functional analysis with special emphasis on insertional mutagenesis, targeted gene disruption by homologous recombination, RNA interference, virusinduced gene silencing (VIGS) technology, and Targeting Induced Local Lesions IN Genomes (TILLING). In addition progress in some areas of transcriptomics research in Musa is reviewed. Insertional mutagenesis has been widely used for cloning genes, promoters, enhancers and other regulatory sequences in the model plant Arabidopsis. Insertional mutagenesis provides a direct route to determining function. Most other approaches are correlative and do not necessarily prove a causal relationship between gene sequence and function. Gene targeting by homologous recombination, although cumbersome, is now feasible in rice. RNA interference (RNAi) is based on sequence-specific RNA degradation that follows the formation of double-stranded RNA (dsRNA) homologous in sequence to the targeted gene. RNAi
Banana production in the East African region is constrained by a variety of pests and diseases. H... more Banana production in the East African region is constrained by a variety of pests and diseases. Host plant resistance is the most convenient and effective intervention to circumvent these constraints in banana production. However, male fertility is a major limitation in the genetic improvement of bananas. Pollen quantity and quality are the key attributes in selecting male parents for successful banana crosses. Pollen was collected from 22 candidate diploid banana hybrids and 6 diploid genotypes previously, successfully used in breeding programs. It was examined for pollen quantity, staining with Iodine Potassium Iodide (I 2 KI, Lugol stain), and germination frequency on a nectar-water medium. The traits under examination varied significantly (P<0.05) among diploid banana hybrids. I 2 KI-stained pollen frequency ranged between 12.96% for hybrid ‘12506S-1’ to 100% for ‘3162K-1’, while pollen tube germination frequency ranged from 1.67% on ‘2858K-5’ to 95.66% on ‘Calcutta 4’. Relat...
Poor reproductive development in yams (Dioscorea spp.) has often been attributed to the polyploid... more Poor reproductive development in yams (Dioscorea spp.) has often been attributed to the polyploid nature of the crop. In this study, flow cytometry was used to determine the ploidy level of 53 accessions of Dioscorea alata, mostly from West African countries, Chad and Puerto Rico. Nuclei were isolated from young leaf material and stained with DAPI (4,6-diamidino-2-phenylindole). The nuclear genome size (2C) was measured as an indicator of the ploidy level. Dioscorea rotundata genotypes with known ploidy levels were used as standards. The results showed that the majority of plants were hexaploid (84.9%) with a smaller percentage of tetraploids (15.1%). A higher number of male plants were hexaploid than tetraploids. This is at variance with earlier findings, which reported that hexaploid male plants are rare. Higher ploidy levels were not directly related to sparse or erratic flowering as previously reported as profuse flowering occurred in some male hexaploid accessions. These findings have important implications for yam breeding in relation to yam genetic resources.
... of Tropical Agriculture, Onne station, Nigeria (Table 1). DNA extraction and AFLP procedure A... more ... of Tropical Agriculture, Onne station, Nigeria (Table 1). DNA extraction and AFLP procedure About 10 g of leaf tissues per sample, collected from the field in liquid nitrogen, were ground with a mortar and pestle. DNA extraction, AFLP procedure and data analysis were as ...
TAG Theoretical and Applied Genetics, 2002
Genetic diversity and relationships were assessed in 28 accessions of Musa acuminata (AA) Colla a... more Genetic diversity and relationships were assessed in 28 accessions of Musa acuminata (AA) Colla and Musa balbisiana (BB) Colla, and some of their natural hybrids, using the amplified fragment length polymorphisms (AFLP) technique. Fifteen AFLP +3 primer pairs produced 527 polymorphic bands among the accessions. Neighbor-joining and principal co-ordinate (PCO) analyses using Jaccard's similarity coefficient produced four major clusters that closely corresponded with the genome composition of the accessions (AA, BB, AAB and ABB). The AFLP data distinguished between the wild diploid accessions and suggested new subspecies relationships in the M. acuminata complex that are different from those based on morphological data. The data suggested that there are three subspecies within the M. acuminata complex (ssp. burmannica Simmonds, malaccensis Simmonds, and microcarpa Simmonds). 'Tjau Lagada' (ssp. microcarpa), 'Truncata' [ssp truncata (Ridl.) Shepherd] and 'SF247' [ssp. banksii (F.Muell) Simmonds] clustered very closely with 'Gros Michel' and 'Km 5', indicating that more than one M. acuminata subspecies may be involved in the origin of triploid AAA bananas. 'Calcutta 4' (ssp. burmannicoides De Langhe & Devreux) and 'Long Tavoy' (ssp. burmannica) were closely related and could be together in the same subspecies. This study also showed that there is much more genetic diversity within M. balbisiana that was split into two groups: (1) 'I-63' and 'HND' and (2) 'Los Banos', 'MPL' (Montpellier), '10852', 'Singapuri', 'Etikehel', and 'Butohan 1' as the other.
TAG Theoretical and Applied Genetics, 2003
The objective of this study was to construct a molecular phylogeny of the genus Musa using restri... more The objective of this study was to construct a molecular phylogeny of the genus Musa using restriction-site polymorphisms of the chloroplast (cpDNA) and mitochondrial DNA (mtDNA). Six cpDNA and two mtDNA sequences were amplified individually in polymerase chain reaction (PCR) experiments in 13 species representing the four sections of Musa. Ensete ventricosum (W.) Ch. was used as the outgroup. The amplified products were digested with ten restriction endonucleases. A total of 79 restriction-site changes were scored in the sample. Wagner parsimony using the branch and bound option defined two lines of evolution in Musa. One lineage comprised species of the sections Australimusa and Callimusa which have a basic number of x = 10 chromosomes, while most species of sections Eumusa and Rhodochlamys ( x = 11) formed the other lineage. Musa laterita Cheesman ( Rhodochlamys) had identical organellar genome patterns as some subspecies of the Musa acuminata Colla complex. The progenitors of the cultivated bananas, M. acuminata and Musa balbisiana Colla, were evolutionarily distinct from each other. Musa balbisiana occupied a basal position in the cladogram indicating an evolutionarily primitive status. The close phylogenetic relationship between M. laterita and M. acuminata suggests that species of the section Rhodochlamys may constitute a secondary genepool for the improvement of cultivated bananas.
TAG Theoretical and Applied Genetics, 2003
Fifteen AFLP primer pairs (EcoRI+3 and MseI+3) and 60 10-mer RAPD primers were used to detect pol... more Fifteen AFLP primer pairs (EcoRI+3 and MseI+3) and 60 10-mer RAPD primers were used to detect polymorphisms and assess genetic relationships in a sample of 25 plantains from diverse parts of Western and Central Africa. The discriminatory power of the AFLP technique was greater than that of the RAPD technique, since the former produced markers with greater polymorphic information content (PIC) than the latter. Hence, AFLP analysis appeared to be a more-powerful approach for identifying genetic differences among plantain accessions. In this regard, significant genetic diversity within the plantains was shown by the unweighted pair-group method of arithmetic averages (UPGMA) and the multidimensional principal coordinate (PCO) analyses. The AFLP-derived clusters indicated closer relationships between similar inflorescence types than the RAPD-derived clusters. A small group of cultivars from Cameroon were separated from the bulk of other plantains, suggesting that Cameroon may harbour accessions with useful or rare genes for widening the genetic base of breeding populations derived from the plantains. A greater effort should be directed at collecting and characterizing plantain cultivars from Cameroon.
Theoretical and Applied Genetics, 1990
Chloroplast DNA (cpDNA) restriction endonuclease patterns are used to examine phylogenetic relati... more Chloroplast DNA (cpDNA) restriction endonuclease patterns are used to examine phylogenetic relationships between Bromus subgenera Festucaria and Ceratochloa. Festucaria is considered monophyletic based on the L genome, while Ceratochloa encompasses two species complexes: the B. catharticus complex, which evolved by combining three different genomes, and the B. carinatus complex, which is thought to have originated from hybridization between polyploid species of B. catharticus and diploid members of Festucaria. All species of subgenus Ceratochloa (hexaploids and octoploids) were identical in chloroplast DNA sequences. Similarly, polyploid species of subgenus Festucaria, except for B. auleticus, were identical in cpDNA sequences. In contrast, diploid species of subgenus Festucaria showed various degrees of nucleotide sequence divergence. Species of subgenus Ceratochloa appeared monophyletic and phylogenetically closely related to the diploid B. anomalus and B. auleticus of subgenus Festucaria. The remaining diploid and polyploid species of subgenus Festucaria appeared in a distinct grouping. The study suggests that the B. catharticus complex must have been the maternal parent in the proposed hybrid origin of B. carinatus complex. Although there is no direct evidence for the paternal parent of the latter complex, the cpDNA study shows the complex to be phylogenetically very related to the diploid B. anomalus of subgenus Festucaria.
Theoretical and Applied Genetics, 1996
Random amplified polymorphic DNA (RAPD) marker-based analysis was carried out to study the extent... more Random amplified polymorphic DNA (RAPD) marker-based analysis was carried out to study the extent of genetic polymorphism between populations of the two endangered Himalayan poppy species, Meconopsis paniculata and M. Simplicifolia. Of the 90 primers tested, 38 revealed marked inter-species genetic polymorphism between individuals of the two species from geographically isolated populations. However, intra-species genetic homogeneity was also evident with respect to a number of primers both within and between populations. A comprehensive analysis incorporating data from RAPDs, DNA fingerprinting and isozyme pattern was carried out and, based on the presence or absence of bands, three matrices of similarity indices were estimated. These matrices were subsequently utilized in cluster analysis. In order to compare the three clusters generated using these three different marker systems, a Mantel matrix-correspondence test was carried out on the basis of comparisons of co-phenetic values. The overall representation of relationships by cluster analysis was similar for all three marker systems and this was substantiated by high correlations among the three analyses revealed by the Mantel matrix-correspondence test. Our results point to very low or absence of, genetic polymorphism in M. paniculata and M. simplicifolia, and are in broad agreement with our previous observations on genetic diversity of Meconopsis species which point to a genetic basis for the possible extinction of this economically important genus.
Theoretical and Applied Genetics, 1996
Genetic variation was assessed among cultivated and wild hop, Humulus lupulus, by restriction fra... more Genetic variation was assessed among cultivated and wild hop, Humulus lupulus, by restriction fragment length polymorphisms (RFLPs) of the ribosomal RNA genes (rDNA). Two rDNA length variants of 10.3 and 9.3 kbp represented by three phenotypes designated A, B and C were detected with XhoI. Restriction-site mapping showed that hop rDNA is structurally similar to those of most higher plants. A high level of homogeneity existed in rDNA repeat lengths among the diverse hop genotypes. Generally, phenotype A was predominant in wild and cultivated European and Asian genotypes; phenotype B in North American cultivars; while phenotype C was present only in native North American hop, providing a potential molecular marker for the identification of this germ plasm. The rDNA data provided genetic evidence for the separation of native and cultivated American genotypes and supports the hypothesis that North American hop cultivars are of hybrid origin from European and native American genotypes. The segregation of rDNA phenotypes in four F1 families suggests that a single locus with two co-dominant alleles controls genetic variability for rDNA variants in hop.
Plant Systematics and Evolution, 2006
The structural organization of the nuclear ribosomal DNA (rDNA) of Humulus lupulus, H. japonicus ... more The structural organization of the nuclear ribosomal DNA (rDNA) of Humulus lupulus, H. japonicus and Cannabis sativa was determined by restriction site mapping. A high degree of DNA sequence similarity was evident in the coding regions of the rDNA repeats of the taxa and supports the placement of Cannabis and Humulus in one family, Cannabaceae. However, the presence of a BstEII site, an additional SacI site, absence of the SpeI site and positional differences of the SspI sites in the 25 S gene distinguished H. japonicus from H. lupulus. Humulus lupulus has an additional EcoRV site in the IGS region. A XhoI site in the 18S region of C. sativa distinguishes it from the two hop species. The diagnostic differences in the IGS of C. sativa include the EcoRI, HindIII and XhoI sites. These sites were not detected in the IGS of the two hop species.
Plant Breeding, 2005
... EA Ogundiwin 1,2 , G. Thottappilly1 , ME Aken'Ova3 , M. Pillay1 and CA Fatokun1,4,5 ... more ... EA Ogundiwin 1,2 , G. Thottappilly1 , ME Aken'Ova3 , M. Pillay1 and CA Fatokun1,4,5 1International Institute of Tropical Agriculture, PMB ... There is however a strong crossing barrier between cowpea and V. vexillata (Evans 1976, Barone and Ng 1990, Fatokun 2002) and this ...
Journal of New Seeds, 2009
Genetic improvement of bananas is hampered by male and female sterility in most of the cultivated... more Genetic improvement of bananas is hampered by male and female sterility in most of the cultivated varieties. In addition, the triploid status of the edible varieties results in very low seed set during artificial hybridizations. The objective of this study was to determine the optimal periods in the year for seed set in East African Highland banana hybrids by examining
Journal of Crop Improvement, 2007
Abstract This study investigates the economic impact of banana Xanthomonas wilt (bxw) and drought... more Abstract This study investigates the economic impact of banana Xanthomonas wilt (bxw) and drought on banana production in Uganda. The objective of this research is to determine the benefits of targeted research to avoid economic losses. In the worst-case scenarios, ...
Genome, 2000
Plantains and bananas (Musa spp. sect. eumusa) originated from intra-and interspecific hybridizat... more Plantains and bananas (Musa spp. sect. eumusa) originated from intra-and interspecific hybridization between two wild diploid species, M. acuminata Colla. and M. balbisiana Colla., which contributed the A and B genomes, respectively. Polyploidy and hybridization have given rise to a number of diploid, triploid, and tetraploid clones with different permutations of the A and B genomes. Thus, dessert and highland bananas are classified mainly as AAA, plantains are AAB, and cooking bananas are ABB. Classification of Musa into genomic groups has been based on morphological characteristics. This study aimed to identify RAPD (random amplified polymorphic DNA) markers for the A and B genomes. Eighty 10-mer Operon primers were used to amplify DNA from M. acuminata subsp. burmannicoides clone 'Calcutta 4' (AA genomes) and M. balbisiana clone 'Honduras' (BB genomes). Three primers (A17, A18, and D10) that produced unique genome-specific fragments in the two species were identified. These primers were tested in a sample of 40 genotypes representing various genome combinations. The RAPD markers were able to elucidate the genome composition of all the genotypes. The results showed that RAPD analysis can provide a quick and reliable system for genome identification in Musa that could facilitate genome characterization and manipulations in breeding lines.
Genome, 1997
Variation in the ribosomal RNA genes (rDNA) was examined to assess the genetic variability among ... more Variation in the ribosomal RNA genes (rDNA) was examined to assess the genetic variability among 314 plants representing 28 accessions of Eragrostis tef, an important food crop. A restriction site map was constructed for the species by localization of the BamHI, BglII, DraI, EcoRI, EcoRV, NdeI, SacI, SpeI, XbaI, and XhoI sites. A comparison of this map with those of other grasses showed conservation of sites, especially in the coding region. However, a unique EcoRI site combined with a BamHI site in the 18S region may be of diagnostic value for the species. A BamHI fragment that spans the intergenic spacer was used as an indicator of length variation of rDNA repeat units. rDNA repeat units in E. tef ranged in size from 8.4 to 11.07 kbp. Considerable size variation of rDNA repeats was present among accessions, between individual plants within some accessions, and within single plants. A total of 19 spacer length (sl) phenotypes was observed in 16 accessions in which 11-42 plants were analyzed. A single restriction site polymorphism was detected in PI442115 that was also distinguished by having a single sl variant. Variation in the rRNA genes is a useful indicator of genetic diversity in E. tef germplasm.
Banana Breeding and …, 2011
... Vuylsteke, 1995). This makes crossbreeding of plantain and banana difficult. Nonetheless, sev... more ... Vuylsteke, 1995). This makes crossbreeding of plantain and banana difficult. Nonetheless, several triploid plan-tain and banana cultivars produce seeds after hand pollination with diploid parents (Ssebuliba et al., 2006). Axenic in ...
Crop Science, 1999
protection and (ii) early detection of agronomic and economic traits as an aid to marker assisted... more protection and (ii) early detection of agronomic and economic traits as an aid to marker assisted selection. Variation in the ribosomal RNA genes (rDNA) and amplified Ribosomal DNA (rDNA) is a well-characterized fragment length polymorphism (AFLP) markers has been used to establish the extent of genetic diversity and relatedness in plants. The multi-gene family in plants which is organized in tandem utility of these methods to detect inter- and intra-specific variation repeats. Each repeat contains DNA sequences coding in cotton (Gossypium spp.) has not been reported and could be useful for the 18S, 5.8S, and 25S ribosomal RNA, and an in- in cultivar identification and in marker assisted selection. The objec- tergenic region generally called the intergenic spacer tives of this study were to: (i) determine the molecular organization region or IGS (Rogers and Bendich, 1987). The 5.8S of the rDNA genes by restriction enzyme mapping and (ii) assess the coding region separates the 18S and 25S regions and is level of AFLPs in Old and New World species of cotton. A restriction bordered by two internal spacer regions referred to as site map of the rDNA gene structure of G. hirsutum L. cv. TM1 ITS1 and ITS2. Molecular studies of variability in rDNA was constructed from DNA digested with 12 restriction enzymes and show that the coding region is highly conserved while hybridized to heterologous probes. Four EcoRI-MseI primer-pair the spacer region is highly variable in sequence and combinations were used for the AFLP analysis. The rDNA gene structure in cotton was found to be similar to that of most higher length. Variation patterns in rDNA have been used : (i) plants. The rDNA repeat size was 9.4 kbp in G. hirsutum and to characterize genetic diversity in plants, (ii) to assess G. barbadense L., and 9.6 and 9.8 kbp in G. arboreum L. and G. changes in the genetic composition of breeding popula- herbaceum L., respectively. No intraspecific polymorphism was de- tions, (iii) to determine phylogenetic relationships at tected in the spacer. The presence of two SspI sites in G. arboreum different levels of the taxonomic hierarchy, and (iv) as and G. herbaceum and a single site in G. hirsutum and G. barbadense important genetic markers. separated Old and New World cottons. The AFLP method produced AFLP is polymerase chain reaction (PCR) based a 10-fold increase in the number of DNA bands per plant, compared marker technology that involves three essential steps: with random amplified polymorphic DNA (RAPD) methods. The (i) digestion of genomic DNA with two restriction en-
Euphytica, 2001
The ploidy levels of the twenty-two yam (Dioscorea cayenensis-D. rotundata complex) cultivars wit... more The ploidy levels of the twenty-two yam (Dioscorea cayenensis-D. rotundata complex) cultivars within germplasm Cameroon Guinea yam were determined by flow cytometry. Three different ploidy levels (4x, 6x, 8x) were detected within the samples analysed. Fifteen cultivars were tetraploids, five were hexaploids, and two were octoploids. The cultivar group EKOTO showed a high level of ploidy variation with tetraploid, hexaploid and octoploid cultivars. The hexaploid nature of cultivars Dobnawo and Bilougnou supported the hypothesis that they are hybrids between cultivars of the EKOTO group and either the KPE or BAKOKAE groups.