Prospects of endosperm DNA in maize seed characterization

DNA based characterisation of maize germplasm has become the easiest and fastest approach to identify genetic diversity as compared to phenotyping. The conventional DNA source for genotyping is the leaf which required at least 2 weeks waiting period from seed planting to leaves sampling. This work exploits the use of endosperm DNA (EDNA) for the genotyping of maize germplasm. Maize endosperm was excised from maize seeds using pli¬ers, ground and used for Genomic DNA extraction (gDNA). Leaves DNA (LDNA) was also extracted concurrently. The extracted LDNA and EDNA were quantified and subjected to SSR-PCR. The mean concentrations of DNA extracted were 1575 ng/ul for the leaves and 526 ng/ul for endosperm. Though the difference in quantity of EDNA and LDNA were highly significant, the quality (A260/A280) for both EDNA and LDNA fall within 1.6-1.8 range of pure DNA index. SSR-PCR products using phi032 were similar for both EDNA and LDNA, indicating the usability of EDNA in genotyping. This seed based method of gDNA extraction takes less than 24 hours from sampling to quantification and genotyping. It also allows germination of sampled seeds, selection before planting, avoids the delay of planting and waiting in leaf sampling and saves field space

Genetics of carotenoids for provitamin A biofortification in tropical-adapted maize

Yellow maize contains high levels of β-carotene (βC), making it an important crop for combating vitamin A deficiency through biofortification. In this study, nine maize inbred lines were selected at random from 31 provitamin A (PVA) maize inbred lines and crossed in a partial diallel mating design to develop 36 crosses. The crosses were evaluated in the field in two locations (Samaru and Kerawa) and their seed carotenoid content were determined by high-performance liquid chromatography. The modes of gene action, heritability, and correlations between agronomic traits and carotenoid content were estimated. Additive genetic variances (σ2a) were lower than non-additive genetic variances (σ2d) for all the carotenoids, plant height (PH), and grain yield (GY), suggesting a preponderance of non-additive gene action. Broad-sense heritability (H2) was high (H2 > 60%) for zeaxanthin, days to anthesis, and PH, moderate (30% < H2 < 60%) for lutein and GY, and low (H2 < 30%) for alpha carotene, beta cryptoxanthin, βC, and PVA. Genetic advance as a percentage of mean, considered with H2, also suggests a preponderance of non-additive gene action for PVA carotenoids. Hybrid variety development is thus an appropriate approach to improving grain yield and PVA. GY showed no significant genotypic correlations with carotenoid content, suggesting that these traits can be improved concurrently. Thus, there is ample scope for improvement of PVA and GY in the sample of tropical-adapted maize