Maryke Labuschagne | University of the Free State (original) (raw)

Papers by Maryke Labuschagne

Compendium of Crop Genome Designing for Nutraceuticals

Plants

Abiotic constraints such as salinity stress reduce cereal production. Salicylic acid is an elicit... more Abiotic constraints such as salinity stress reduce cereal production. Salicylic acid is an elicitor of abiotic stress tolerance in plants. The aim of this study was to investigate the effects of salicylic acid on two bread wheat cultivars (SST806 and PAN3497) grown under salt stress (100 and 200 mM NaCl) in the presence and absence of 0.5 mM salicylic acid. The highest salt concentration (200 mM), in both PAN3497 and SST806, increased the days to germination and reduced the coleoptile and radicle dry weights. The shoot dry weight was reduced by 75 and 39%, root dry weight by 73 and 37%, spike number of both by 50%, spike weight by 73 and 54%, grain number by 62 and 15%, grain weight per spike by 80 and 45%, and 1000 grain weight by 9 and 29% for 200 and 100 mM NaCl, respectively. Salicylic acid in combination with 100 mM and 200 mM NaCl increased the shoot, root, and yield attributes. Salicylic acid increased the grain protein content, especially at 200 mM NaCl, and the increase was...

Frontiers in Sustainable Food Systems

IntroductionBiofortified maize varieties could contribute to the fight against hunger and malnutr... more IntroductionBiofortified maize varieties could contribute to the fight against hunger and malnutrition of the increasing human population and help meet the high demand of maize for human consumption, industrial use and feed for animal and poultry. The understanding of the genetic mechanisms conditioning the inheritance of grain yield and other agronomic and quality traits is essential in the development of superior maize genotypes. The main objective of this study was to determine the combining ability for grain yield and other agronomic traits of QPM and non-QPM inbred lines crossed with two QPM and two non-QPM testers.Materials and methodsA total of 130 hybrids were obtained by crossing 10 non-QPM and 23 QPM lines with four elite testers (two QPM and two non-QPM). The 130 single cross hybrids were evaluated at 13 sites in 2018 and 2019.Results and discussionThe results showed significant general combining ability (GCA) for lines and testers as well as significant specific combinin...

Agronomy, Jul 30, 2022

This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY

Euphytica, 2020

Small-scale maize farmers in sub-Saharan Africa use meager amounts of nitrogen (N) in their maize... more Small-scale maize farmers in sub-Saharan Africa use meager amounts of nitrogen (N) in their maize crops. N use efficient varieties can provide a solution to the problem of low N conditions through efficient N uptake and utilization. The objectives of this study were to i) compare the quantitative genetic parameters of grain yield and secondary traits under different nitrogen levels and ii) assess the efficiency of indirect selection for grain yield under low N stress through yield under optimum N and secondary traits under low N stress in maize. Doubled haploid lines derived from five bi-parental populations were evaluated. Genotype effect for grain yield and secondary traits was significant at all sites. Genetic variance for grain yield was reduced by 17% under moderate N stress and 63% under severe N stress conditions, while genetic variance for days to anthesis and plant height increased under both moderate and severe low N stress. The heritability of most secondary traits was consistently higher than that of grain yield. Correlations of grain yield with plant and ear heights were positive under low N conditions. Despite the reduction in genetic variances under low N conditions, there was genetic variability for grain yield and secondary traits. Direct selection for grain yield under low N rather than under optimum conditions was more efficient for yield improvement under the low N condition. The use of an index of secondary traits could increase the efficiency of improving grain yield rather than selection for only grain yield under low N conditions.

Cereal Research Communications, 2003

Thirty advanced lines and cultivars were investigated for their specific B-LMW glutenin (LMW-1 an... more Thirty advanced lines and cultivars were investigated for their specific B-LMW glutenin (LMW-1 and LMW-2) and γ-gliadin (γ-42 and γ-45) composition by SDS-PAGE. Their relationship to SDS-sedimentation volume (SDSS), mixograph development time (MDT) and loaf volume (LFV) were studied. The proportion of genotypes with LMW-2/γ-45 was much higher than LMW-1/γ-42 types. Lines with LMW-2/γ-45 had higher SDSS, MDT and LFV values. Line CD96486 having subunits N, 7+8 and LMW-2/γ-45 had the highest LFV and it had better values for SDSS and MDT than the rest of the genotypes. The high proportion of advanced lines having LMW-2/γ-45, which is genetically related to good grain quality, is an advantage for selection of suitable genotypes for intended products. Selection for higher values of SDSS and optimum MDT usually leads to better loaf volume. Screening of genotypes using wheat storage proteins as genetic markers will help to devise an effective breeding program for the region.

Cereal Research Communications

Cereal Research Communications, 2016

The mixograph performs certain rheological measurements during dough mixing and is a good predict... more The mixograph performs certain rheological measurements during dough mixing and is a good predictor of wheat end-use quality. The aim of this study was to determine the expression and the heritability of mixing characteristics measured with Mixsmart® software and some quality characteristics in hard red spring wheat parents and their F 1 progeny. Six parents varying in midline peak time and envelope peak time were crossed in a half diallel design. Parents and progeny were planted in three different environments. General combining ability (GCA) was a significant source of variation for the measured characteristics, and parents differed widely in terms of GCA effects. Midline-development time,-peak integral and-peak time showed high narrow sense heritability. Envelope peak-integral and-tail width displayed high narrow sense heritability for some, but not all locations. High GCA:SCA (specific combining ability) ratios indicated the prevalence of additive gene effects for midline-development time,-peak integral and-peak time, indicating that these characteristics are largely genetically determined, and that selection for them should lead to genetic gain.

Agronomy

Fall armyworm (Spodoptera frugiperda (J.E. Smith); FAW)-resistant cultivars and breeding lines ha... more Fall armyworm (Spodoptera frugiperda (J.E. Smith); FAW)-resistant cultivars and breeding lines have been identified in sub-Saharan Africa. However, these genotypes have not been evaluated for their stability across environments with natural FAW infestation. The objectives of this study were to: (i) identify hybrids/open pollinated varieties combining high grain yield (GYD) and stability across environments with natural FAW infestation, (ii) select maize inbred lines with high GYD and stable FAW resistance, and (iii) identify the most discriminating environments for GYD performance and foliar FAW damage (FFAWD) under natural FAW infestation. The additive main effect and multiplicative interaction (AMMI) model was used to detect the presence of genotype-by-environment interaction (GEI) for GYD, and foliar and ear FAW damage. Seven stability analysis models were used to analyse adaptation and stability of genotypes across environments. The hybrids Mutsa-MN521 and CimExp55/CML334 were t...

Plants

Currently, the world population is increasing, and humanity is facing food and nutritional scarci... more Currently, the world population is increasing, and humanity is facing food and nutritional scarcity. Climate change and variability are a major threat to global food and nutritional security, reducing crop productivity in the tropical and subtropical regions of the globe. Cowpea has the potential to make a significant contribution to global food and nutritional security. In addition, it can be part of a sustainable food system, being a genetic resource for future crop improvement, contributing to resilience and improving agricultural sustainability under climate change conditions. In malnutrition prone regions of sub-Saharan Africa (SSA) countries, cowpea has become a strategic dryland legume crop for addressing food insecurity and malnutrition. Therefore, this review aims to assess the contribution of cowpea to SSA countries as a climate-resilient crop and the existing production challenges and perspectives. Cowpea leaves and immature pods are rich in diverse nutrients, with high l...

Plants

Abiotic constraints such as water deficit reduce cereal production. Plants have different strateg... more Abiotic constraints such as water deficit reduce cereal production. Plants have different strategies against these stresses to improve plant growth, physiological metabolism and crop production. For example, arbuscular mycorrhiza (AM)—bread wheat association has been shown to improve tolerance to drought stress conditions. The objective of this study was to determine the effect of AM inoculation on plant characteristics, lipid peroxidation, solute accumulation, water deficit saturation, photosynthetic activity, total phenol secretion and enzymatic activities including peroxidise (PO) and polyphenol oxidase (PPO) in two bread wheat cultivars (PAN3497 and SST806) under well-watered and drought-stressed conditions in plants grown under greenhouse conditions, to determine whether AM can enhance drought tolerance in wheat. AM inoculation improved morphological and physiological parameters in plants under stress. The leaf number increased by 35% and 5%, tiller number by 25% and 23%, chlor...

Maydica, 2018

Single nucleotide polymorphism (SNP) markers are regarded as efficient,compared to other marker t... more Single nucleotide polymorphism (SNP) markers are regarded as efficient,compared to other marker types in genetic characterization of maize (Zea mays L.) germplasm because of their vast coverage of the maize genome. The objectives of this study were to (a) genetically fingerprint few-branched-1’ (Fbr1) and normal tasselled CIMMYT elite lines using SNP markers, to assess their relatedness and level of homozygosity and (b) to determine SNP-based genetic distance among these maize lines and to find association of genetic distances with specific combining ability (SCA), mid-parent heterosis (MPH), high-parent heterosis (HPH) and mean grain yield of the hybrids. Twenty-six CIMMYT maize lines (12 with the Fbr1 gene, and 14 normal-tasselled) were genotyped using 1074 SNP marker loci. Fifteen of these lines were used in two separate diallel mating designs: a 9x9 and 6x6 crossing set-up, to make hybrids for yield evaluation. Average residual heterozygosity of SNP loci ranged from 0.2-36.1%, w...

Agronomy

Fall armyworm [Spodoptera frugiperda (J./E. Smith); FAW] is negatively impacting sustainable maiz... more Fall armyworm [Spodoptera frugiperda (J./E. Smith); FAW] is negatively impacting sustainable maize production, particularly in smallholder farming systems in sub-Saharan Africa. Two sets of germplasm (commercial cultivars and experimental hybrids, and local and exotic inbred lines) were evaluated under managed and natural FAW infestation to identify FAW tolerant material with superior grain yield performance. Significant genotypic effects on foliar FAW damage, ear FAW damage, and grain yield were observed. Commercial cultivars were significantly more affected by FAW infestation than experimental hybrids, as evidenced by high foliar and ear damage scores, yet they out-yielded experimental genotypes. The introduced FAW donor lines (CML338, CML67, CML121, and CML334) showed better tolerance to FAW, individually and in hybrid combinations. Local inbred lines, SV1P, CML491, and CML 539, also showed FAW tolerance. Hybrids and open pollinated varieties were more vulnerable to FAW damage at...

Journal of Food Composition and Analysis, 2012

ABSTRACT The content of trans-b-carotene and selected minerals was determined in 12 sweetpotato (... more ABSTRACT The content of trans-b-carotene and selected minerals was determined in 12 sweetpotato (Ipomoea batatas) varieties produced at 4 agro-geographical production sites in South Africa. All 9 orange-fleshed varieties have the potential to contribute _100% of the recommended dietary allowance of 4–8 year-old children for vitamin A, 27% for magnesium, 15% for zinc and 11% for iron. Orange-fleshed varieties were superior to cream-fleshed ones in calcium and magnesium content. The trans-b-carotene content of the varieties varied over the geographical sites. The mean content in the 9 orange-fleshed varieties was between 5091 and 16,456 mg/100 g fresh weight. The mineral content in fresh roots of the 12 varieties ranged from 34 to 63 mg/100 g for calcium, 15 to 37 mg/100 g for magnesium, 28 to 51 mg/100 g for phosphorus, 191 to 334 mg/100 g for potassium, 0.73 to 1.26 mg/100 g for iron, and 0.51 to 0.69 mg/100 g for zinc. Variation within varieties over geographical sites could be ascribed to differences in soil mineral content, soil pH and the interaction of these. The variation in nutritional content of sweetpotato indicated here, needs to be considered in varietal selection for different production sites and in calculating nutrient contribution of sweetpotato toward dietary intake.

Euphytica, 2017

Maize is not inherently tolerant to soil acidity but due to the ever increasing demand for the cr... more Maize is not inherently tolerant to soil acidity but due to the ever increasing demand for the crop in the developing world, production of maize on acid soils continues to expand. Breeding for maize acid soil tolerance is the best strategy to improve yield under these conditions. Therefore, the current study was done to determine the general combining ability (GCA) of eight acid-soil tolerant and susceptible inbred lines and the specific combining ability (SCA) of cross combinations of these lines for grain yield under acid and non-acid soils. The eight lines were crossed using a diallel mating design to produce 28 single cross hybrids for evaluation under acid and nonacid soils at four sites for two seasons. Line C2 was the best general combiner under both soil environments while A2/C1 and A1/C2 had the highest desirable SCA effects under optimal conditions. Loss in grain yield and sensitivity to low pH stress was higher among genotypes in light textured soils than heavy soils. Non-additive gene action was more important than additive gene action in conditioning grain yield under both environments. Results revealed that it was feasible to improve grain yield under low pH and optimum soils from the set of genotypes used in the current study.

Single nucleotide polymorphism (SNP) markers are regarded as efficient,compared to other marker t... more Single nucleotide polymorphism (SNP) markers are regarded as efficient,compared to other marker types in genetic characterization of maize (Zea mays L.) germplasm because of their vast coverage of the maize genome. The objectives of this study were to (a) genetically fingerprint few-branched-1’ (Fbr1) and normal tasselled CIMMYT elite lines using SNP markers, to assess their relatedness and level of homozygosity and (b) to determine SNP-based genetic distance among these maize lines and to find association of genetic distances with specific combining ability (SCA), mid-parent heterosis (MPH), high-parent heterosis (HPH) and mean grain yield of the hybrids. Twenty-six CIMMYT maize lines (12 with the Fbr1 gene, and 14 normal-tasselled) were genotyped using 1074 SNP marker loci. Fifteen of these lines were used in two separate diallel mating designs: a 9x9 and 6x6 crossing set-up, to make hybrids for yield evaluation. Average residual heterozygosity of SNP loci ranged from 0.2-36.1%, w...

African Journal of Biotechnology, 2013

Amplified fragment length polymorphism (AFLP) analysis was used to assess the genetic relationshi... more Amplified fragment length polymorphism (AFLP) analysis was used to assess the genetic relationships among 46 accessions of sorghum ( Sorghum bicolor (L.) Moench) collected from the north-western, western and central parts of Ethiopia as well as South Africa. Six AFLP primer combinations were used for the analysis of DNA fragment amplification. Dice similarity coefficients were calculated and a dendrogram was constructed following the UPGMA method of cluster analysis. A total of 186 fragments were amplified of which 78 (43.10%) were polymorphic. The number of polymorphic fragments amplified per primer combination varied from 9 to 21. Genetic polymorphism present among sorghum accessions was low, as evidenced by the high level of similarity in the AFLP marker profiles of different sorghum accessions. Pair-wise genetic similarity coefficients ranged from 0.87 to 0.99, with an average of 0.92. This indicates low levels of genetic diversity among tested sorghum accessions. The landraces ...

Euphytica, 2017

Rice is mainly a self-pollinating crop, but some outcrossing has been reported. Outcrossing with ... more Rice is mainly a self-pollinating crop, but some outcrossing has been reported. Outcrossing with an undesirable donor would lead to the creation of segregants or off-types, which would adversely affect genetic purity and uniformity of the crop. Outcrossing rates in rice under field conditions were investigated using cultivar WAB96-1-1 as a pollen donor and WAB56-104, NERICA 2, NERICA 4 and NERICA 7 as pollen recipients. Levels of outcrossing were investigated up to 30 m from the pollen donor. Dominant morphological markers of red kernel colour and pubescent leaves of the donor were used to identify hybrids. A total of 721 134 plants were investigated. There was an average outcrossing rate of 0.7 ± 0.51%, with a potential outcrossing rate of 2.45 ± 0.86%. Outcrossing rates decreased with increase in distance. It ranged from 2.45% at 0.2 m from the donor to 0.05% at 25 m from the donor. Differences were observed between genotypes and seasons. In season 1 the highest average outcrossing rate of 1.2 ± 0.63% was with WAB56-104 and in season 2 it was 1.1 ± 0.69% with NERICA 4. Outcrossing occurred up to 30 m from the donor. This has implications for germplasm management and conservation and the production of high quality seed. Spatial isolation remains the most practical method to prevent undesirable gene flow. The study indicated that red kernel colour and leaf pubescence can be used to effectively assess outcrossing under field conditions in rice.

Compendium of Crop Genome Designing for Nutraceuticals

Plants

Abiotic constraints such as salinity stress reduce cereal production. Salicylic acid is an elicit... more Abiotic constraints such as salinity stress reduce cereal production. Salicylic acid is an elicitor of abiotic stress tolerance in plants. The aim of this study was to investigate the effects of salicylic acid on two bread wheat cultivars (SST806 and PAN3497) grown under salt stress (100 and 200 mM NaCl) in the presence and absence of 0.5 mM salicylic acid. The highest salt concentration (200 mM), in both PAN3497 and SST806, increased the days to germination and reduced the coleoptile and radicle dry weights. The shoot dry weight was reduced by 75 and 39%, root dry weight by 73 and 37%, spike number of both by 50%, spike weight by 73 and 54%, grain number by 62 and 15%, grain weight per spike by 80 and 45%, and 1000 grain weight by 9 and 29% for 200 and 100 mM NaCl, respectively. Salicylic acid in combination with 100 mM and 200 mM NaCl increased the shoot, root, and yield attributes. Salicylic acid increased the grain protein content, especially at 200 mM NaCl, and the increase was...

Frontiers in Sustainable Food Systems

IntroductionBiofortified maize varieties could contribute to the fight against hunger and malnutr... more IntroductionBiofortified maize varieties could contribute to the fight against hunger and malnutrition of the increasing human population and help meet the high demand of maize for human consumption, industrial use and feed for animal and poultry. The understanding of the genetic mechanisms conditioning the inheritance of grain yield and other agronomic and quality traits is essential in the development of superior maize genotypes. The main objective of this study was to determine the combining ability for grain yield and other agronomic traits of QPM and non-QPM inbred lines crossed with two QPM and two non-QPM testers.Materials and methodsA total of 130 hybrids were obtained by crossing 10 non-QPM and 23 QPM lines with four elite testers (two QPM and two non-QPM). The 130 single cross hybrids were evaluated at 13 sites in 2018 and 2019.Results and discussionThe results showed significant general combining ability (GCA) for lines and testers as well as significant specific combinin...

Agronomy, Jul 30, 2022

This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY

Euphytica, 2020

Small-scale maize farmers in sub-Saharan Africa use meager amounts of nitrogen (N) in their maize... more Small-scale maize farmers in sub-Saharan Africa use meager amounts of nitrogen (N) in their maize crops. N use efficient varieties can provide a solution to the problem of low N conditions through efficient N uptake and utilization. The objectives of this study were to i) compare the quantitative genetic parameters of grain yield and secondary traits under different nitrogen levels and ii) assess the efficiency of indirect selection for grain yield under low N stress through yield under optimum N and secondary traits under low N stress in maize. Doubled haploid lines derived from five bi-parental populations were evaluated. Genotype effect for grain yield and secondary traits was significant at all sites. Genetic variance for grain yield was reduced by 17% under moderate N stress and 63% under severe N stress conditions, while genetic variance for days to anthesis and plant height increased under both moderate and severe low N stress. The heritability of most secondary traits was consistently higher than that of grain yield. Correlations of grain yield with plant and ear heights were positive under low N conditions. Despite the reduction in genetic variances under low N conditions, there was genetic variability for grain yield and secondary traits. Direct selection for grain yield under low N rather than under optimum conditions was more efficient for yield improvement under the low N condition. The use of an index of secondary traits could increase the efficiency of improving grain yield rather than selection for only grain yield under low N conditions.

Cereal Research Communications, 2003

Thirty advanced lines and cultivars were investigated for their specific B-LMW glutenin (LMW-1 an... more Thirty advanced lines and cultivars were investigated for their specific B-LMW glutenin (LMW-1 and LMW-2) and γ-gliadin (γ-42 and γ-45) composition by SDS-PAGE. Their relationship to SDS-sedimentation volume (SDSS), mixograph development time (MDT) and loaf volume (LFV) were studied. The proportion of genotypes with LMW-2/γ-45 was much higher than LMW-1/γ-42 types. Lines with LMW-2/γ-45 had higher SDSS, MDT and LFV values. Line CD96486 having subunits N, 7+8 and LMW-2/γ-45 had the highest LFV and it had better values for SDSS and MDT than the rest of the genotypes. The high proportion of advanced lines having LMW-2/γ-45, which is genetically related to good grain quality, is an advantage for selection of suitable genotypes for intended products. Selection for higher values of SDSS and optimum MDT usually leads to better loaf volume. Screening of genotypes using wheat storage proteins as genetic markers will help to devise an effective breeding program for the region.

Cereal Research Communications

Cereal Research Communications, 2016

The mixograph performs certain rheological measurements during dough mixing and is a good predict... more The mixograph performs certain rheological measurements during dough mixing and is a good predictor of wheat end-use quality. The aim of this study was to determine the expression and the heritability of mixing characteristics measured with Mixsmart® software and some quality characteristics in hard red spring wheat parents and their F 1 progeny. Six parents varying in midline peak time and envelope peak time were crossed in a half diallel design. Parents and progeny were planted in three different environments. General combining ability (GCA) was a significant source of variation for the measured characteristics, and parents differed widely in terms of GCA effects. Midline-development time,-peak integral and-peak time showed high narrow sense heritability. Envelope peak-integral and-tail width displayed high narrow sense heritability for some, but not all locations. High GCA:SCA (specific combining ability) ratios indicated the prevalence of additive gene effects for midline-development time,-peak integral and-peak time, indicating that these characteristics are largely genetically determined, and that selection for them should lead to genetic gain.

Agronomy

Fall armyworm (Spodoptera frugiperda (J.E. Smith); FAW)-resistant cultivars and breeding lines ha... more Fall armyworm (Spodoptera frugiperda (J.E. Smith); FAW)-resistant cultivars and breeding lines have been identified in sub-Saharan Africa. However, these genotypes have not been evaluated for their stability across environments with natural FAW infestation. The objectives of this study were to: (i) identify hybrids/open pollinated varieties combining high grain yield (GYD) and stability across environments with natural FAW infestation, (ii) select maize inbred lines with high GYD and stable FAW resistance, and (iii) identify the most discriminating environments for GYD performance and foliar FAW damage (FFAWD) under natural FAW infestation. The additive main effect and multiplicative interaction (AMMI) model was used to detect the presence of genotype-by-environment interaction (GEI) for GYD, and foliar and ear FAW damage. Seven stability analysis models were used to analyse adaptation and stability of genotypes across environments. The hybrids Mutsa-MN521 and CimExp55/CML334 were t...

Plants

Currently, the world population is increasing, and humanity is facing food and nutritional scarci... more Currently, the world population is increasing, and humanity is facing food and nutritional scarcity. Climate change and variability are a major threat to global food and nutritional security, reducing crop productivity in the tropical and subtropical regions of the globe. Cowpea has the potential to make a significant contribution to global food and nutritional security. In addition, it can be part of a sustainable food system, being a genetic resource for future crop improvement, contributing to resilience and improving agricultural sustainability under climate change conditions. In malnutrition prone regions of sub-Saharan Africa (SSA) countries, cowpea has become a strategic dryland legume crop for addressing food insecurity and malnutrition. Therefore, this review aims to assess the contribution of cowpea to SSA countries as a climate-resilient crop and the existing production challenges and perspectives. Cowpea leaves and immature pods are rich in diverse nutrients, with high l...

Plants

Abiotic constraints such as water deficit reduce cereal production. Plants have different strateg... more Abiotic constraints such as water deficit reduce cereal production. Plants have different strategies against these stresses to improve plant growth, physiological metabolism and crop production. For example, arbuscular mycorrhiza (AM)—bread wheat association has been shown to improve tolerance to drought stress conditions. The objective of this study was to determine the effect of AM inoculation on plant characteristics, lipid peroxidation, solute accumulation, water deficit saturation, photosynthetic activity, total phenol secretion and enzymatic activities including peroxidise (PO) and polyphenol oxidase (PPO) in two bread wheat cultivars (PAN3497 and SST806) under well-watered and drought-stressed conditions in plants grown under greenhouse conditions, to determine whether AM can enhance drought tolerance in wheat. AM inoculation improved morphological and physiological parameters in plants under stress. The leaf number increased by 35% and 5%, tiller number by 25% and 23%, chlor...

Maydica, 2018

Single nucleotide polymorphism (SNP) markers are regarded as efficient,compared to other marker t... more Single nucleotide polymorphism (SNP) markers are regarded as efficient,compared to other marker types in genetic characterization of maize (Zea mays L.) germplasm because of their vast coverage of the maize genome. The objectives of this study were to (a) genetically fingerprint few-branched-1’ (Fbr1) and normal tasselled CIMMYT elite lines using SNP markers, to assess their relatedness and level of homozygosity and (b) to determine SNP-based genetic distance among these maize lines and to find association of genetic distances with specific combining ability (SCA), mid-parent heterosis (MPH), high-parent heterosis (HPH) and mean grain yield of the hybrids. Twenty-six CIMMYT maize lines (12 with the Fbr1 gene, and 14 normal-tasselled) were genotyped using 1074 SNP marker loci. Fifteen of these lines were used in two separate diallel mating designs: a 9x9 and 6x6 crossing set-up, to make hybrids for yield evaluation. Average residual heterozygosity of SNP loci ranged from 0.2-36.1%, w...

Agronomy

Fall armyworm [Spodoptera frugiperda (J./E. Smith); FAW] is negatively impacting sustainable maiz... more Fall armyworm [Spodoptera frugiperda (J./E. Smith); FAW] is negatively impacting sustainable maize production, particularly in smallholder farming systems in sub-Saharan Africa. Two sets of germplasm (commercial cultivars and experimental hybrids, and local and exotic inbred lines) were evaluated under managed and natural FAW infestation to identify FAW tolerant material with superior grain yield performance. Significant genotypic effects on foliar FAW damage, ear FAW damage, and grain yield were observed. Commercial cultivars were significantly more affected by FAW infestation than experimental hybrids, as evidenced by high foliar and ear damage scores, yet they out-yielded experimental genotypes. The introduced FAW donor lines (CML338, CML67, CML121, and CML334) showed better tolerance to FAW, individually and in hybrid combinations. Local inbred lines, SV1P, CML491, and CML 539, also showed FAW tolerance. Hybrids and open pollinated varieties were more vulnerable to FAW damage at...

Journal of Food Composition and Analysis, 2012

ABSTRACT The content of trans-b-carotene and selected minerals was determined in 12 sweetpotato (... more ABSTRACT The content of trans-b-carotene and selected minerals was determined in 12 sweetpotato (Ipomoea batatas) varieties produced at 4 agro-geographical production sites in South Africa. All 9 orange-fleshed varieties have the potential to contribute _100% of the recommended dietary allowance of 4–8 year-old children for vitamin A, 27% for magnesium, 15% for zinc and 11% for iron. Orange-fleshed varieties were superior to cream-fleshed ones in calcium and magnesium content. The trans-b-carotene content of the varieties varied over the geographical sites. The mean content in the 9 orange-fleshed varieties was between 5091 and 16,456 mg/100 g fresh weight. The mineral content in fresh roots of the 12 varieties ranged from 34 to 63 mg/100 g for calcium, 15 to 37 mg/100 g for magnesium, 28 to 51 mg/100 g for phosphorus, 191 to 334 mg/100 g for potassium, 0.73 to 1.26 mg/100 g for iron, and 0.51 to 0.69 mg/100 g for zinc. Variation within varieties over geographical sites could be ascribed to differences in soil mineral content, soil pH and the interaction of these. The variation in nutritional content of sweetpotato indicated here, needs to be considered in varietal selection for different production sites and in calculating nutrient contribution of sweetpotato toward dietary intake.

Euphytica, 2017

Maize is not inherently tolerant to soil acidity but due to the ever increasing demand for the cr... more Maize is not inherently tolerant to soil acidity but due to the ever increasing demand for the crop in the developing world, production of maize on acid soils continues to expand. Breeding for maize acid soil tolerance is the best strategy to improve yield under these conditions. Therefore, the current study was done to determine the general combining ability (GCA) of eight acid-soil tolerant and susceptible inbred lines and the specific combining ability (SCA) of cross combinations of these lines for grain yield under acid and non-acid soils. The eight lines were crossed using a diallel mating design to produce 28 single cross hybrids for evaluation under acid and nonacid soils at four sites for two seasons. Line C2 was the best general combiner under both soil environments while A2/C1 and A1/C2 had the highest desirable SCA effects under optimal conditions. Loss in grain yield and sensitivity to low pH stress was higher among genotypes in light textured soils than heavy soils. Non-additive gene action was more important than additive gene action in conditioning grain yield under both environments. Results revealed that it was feasible to improve grain yield under low pH and optimum soils from the set of genotypes used in the current study.

Single nucleotide polymorphism (SNP) markers are regarded as efficient,compared to other marker t... more Single nucleotide polymorphism (SNP) markers are regarded as efficient,compared to other marker types in genetic characterization of maize (Zea mays L.) germplasm because of their vast coverage of the maize genome. The objectives of this study were to (a) genetically fingerprint few-branched-1’ (Fbr1) and normal tasselled CIMMYT elite lines using SNP markers, to assess their relatedness and level of homozygosity and (b) to determine SNP-based genetic distance among these maize lines and to find association of genetic distances with specific combining ability (SCA), mid-parent heterosis (MPH), high-parent heterosis (HPH) and mean grain yield of the hybrids. Twenty-six CIMMYT maize lines (12 with the Fbr1 gene, and 14 normal-tasselled) were genotyped using 1074 SNP marker loci. Fifteen of these lines were used in two separate diallel mating designs: a 9x9 and 6x6 crossing set-up, to make hybrids for yield evaluation. Average residual heterozygosity of SNP loci ranged from 0.2-36.1%, w...

African Journal of Biotechnology, 2013

Amplified fragment length polymorphism (AFLP) analysis was used to assess the genetic relationshi... more Amplified fragment length polymorphism (AFLP) analysis was used to assess the genetic relationships among 46 accessions of sorghum ( Sorghum bicolor (L.) Moench) collected from the north-western, western and central parts of Ethiopia as well as South Africa. Six AFLP primer combinations were used for the analysis of DNA fragment amplification. Dice similarity coefficients were calculated and a dendrogram was constructed following the UPGMA method of cluster analysis. A total of 186 fragments were amplified of which 78 (43.10%) were polymorphic. The number of polymorphic fragments amplified per primer combination varied from 9 to 21. Genetic polymorphism present among sorghum accessions was low, as evidenced by the high level of similarity in the AFLP marker profiles of different sorghum accessions. Pair-wise genetic similarity coefficients ranged from 0.87 to 0.99, with an average of 0.92. This indicates low levels of genetic diversity among tested sorghum accessions. The landraces ...

Euphytica, 2017

Rice is mainly a self-pollinating crop, but some outcrossing has been reported. Outcrossing with ... more Rice is mainly a self-pollinating crop, but some outcrossing has been reported. Outcrossing with an undesirable donor would lead to the creation of segregants or off-types, which would adversely affect genetic purity and uniformity of the crop. Outcrossing rates in rice under field conditions were investigated using cultivar WAB96-1-1 as a pollen donor and WAB56-104, NERICA 2, NERICA 4 and NERICA 7 as pollen recipients. Levels of outcrossing were investigated up to 30 m from the pollen donor. Dominant morphological markers of red kernel colour and pubescent leaves of the donor were used to identify hybrids. A total of 721 134 plants were investigated. There was an average outcrossing rate of 0.7 ± 0.51%, with a potential outcrossing rate of 2.45 ± 0.86%. Outcrossing rates decreased with increase in distance. It ranged from 2.45% at 0.2 m from the donor to 0.05% at 25 m from the donor. Differences were observed between genotypes and seasons. In season 1 the highest average outcrossing rate of 1.2 ± 0.63% was with WAB56-104 and in season 2 it was 1.1 ± 0.69% with NERICA 4. Outcrossing occurred up to 30 m from the donor. This has implications for germplasm management and conservation and the production of high quality seed. Spatial isolation remains the most practical method to prevent undesirable gene flow. The study indicated that red kernel colour and leaf pubescence can be used to effectively assess outcrossing under field conditions in rice.