Malnutrition has emerged as one of the major health problems worldwide. Traditional yellow maize has low provitamin-A (proA) content and its genetic base in proA biofortification breeding program of subtropics is extremely narrow. To diversify the proA rich germplasm, 10 elite low proA inbreds were crossed with a proA rich donor (HP702-22) having mutant crtRB1 gene. The F2 populations derived from these crosses were genotyped using InDel marker specific to crtRB1. Severe marker segregation distortion was observed. Seventeen crtRB1 inbreds developed through marker-assisted pedigree breeding and seven inbreds generated using marker-assisted backcross breeding were characterized using 77 SSRs. Wide variation in gene diversity (0.08 to 0.79) and dissimilarity coefficient (0.28 to 0.84) was observed. The inbreds were grouped into three major clusters depicting the existing genetic diversity. The crtRB1-based inbreds possessed high β-carotene (BC: 8.72μg/g), β-cryptoxanthin (BCX: 4.58μg/g) and proA (11.01μg/g), while it was 2.35μg/g, 1.24μg/g and 2.97μg/g in checks, respectively. Based on their genetic relationships, 15 newly developed crtRB1-based inbreds were crossed with five testers (having crtRB1 gene) using line × tester mating design. 75 experimental hybrids with crtRB1 gene were evaluated over three locations. These experimental hybrids possessed higher BC (8.02μg/g), BCX (4.69μg/g), proA (10.37μg/g) compared to traditional hybrids used as check (BC: 2.36 μg/g, BCX: 1.53μg/g, proA: 3.13μg/g). Environment and genotypes × environment interaction had minor effects on proA content. Both additive and dominance gene action were significant for proA. The mean proportion of proA to total carotenoids (TC) was 44% among crtRB1-based hybrids, while 11% in traditional hybrids. BC was found to be positively correlated with BCX (r = 0.68) and proA (r = 0.98). However, no correlation was observed between proA and grain yield. Several hybrids with >10.0 t/ha grain yield with proA content >10.0 μg/g were identified. This is the first comprehensive study on development of diverse proA rich maize hybrids through marker-assisted pedigree breeding approach. The findings provides sustainable and cost-effective solution to alleviate vitamin-A deficiency.

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Six parental genotypes and their thirty F 1 hybrids in a full diallel cross system with reciprocals, were used in the present study to estimate combining ability for five quantitative and five qualitative traits in hot pepper. The mean sum of squares due to general combining ability (GCA), specific combining ability (SCA) and reciprocal combining ability (RCA) were significant for all the characters which suggest that these parents could have performed differently in different combinations indicating interallelic interactions. All the traits studied exhibited greater SCA variance than GCA, suggesting that these traits are controlled by non-additive gene action. Analysis of the GCA effects of parents for various traits revealed that LCA625, K1 and PKM1 were the best general combiners for almost all the traits. Estimates of SCA effects showed that the hybrids LCA625 × K1, K1 × Arka Lohit and Pusa Jwala × PKM1 were found to be the best combiners for yield and its attributes. The hybrid K1 × Arka Lohit was the best reciprocal combiner for quality parameters based on its better mean performance and combining ability. These results suggest that commercial production of hot pepper hybrids and isolation of pure lines from these hybrids is a possible way to enhance the yield and fruit quality.Additional key words: chilli; growth; capsaicin; dry yield; GCA; SCA; RCA Authors' contributions: Designed the study: LV, SD, JJA and GP. Data collection, field work and statistical analysis: RN. Technical and material support: LV and SD. Contributed analysis tools: JJA and GP. All authors read and approved the final manuscript.Correspondence should be addressed to Rohini Narayanasamy: rohizna@gmail.com

Several maize breeding programs in India have developed numerous inbred lines but the lines have not been characterized using high-density molecular markers. Here, we studied the molecular diversity, population structure, and linkage disequilibrium (LD) patterns in a panel of 314 tropical normal corn, two sweet corn, and six popcorn inbred lines developed by 17 research centers in India, and 62 normal corn from the International Maize and Wheat Improvement Center (CIMMYT). The 384 inbred lines were genotyped with 60,227 polymorphic single nucleotide polymorphisms (SNPs). Most of the pair-wise relative kinship coefficients (58.5%) were equal or close to 0, which suggests the lack of redundancy in the genomic composition in the majority of inbred lines. Genetic distance among most pairs of lines (98.3%) varied from 0.20 to 0.34 as compared with just 1.7% of the pairs of lines that differed by <0.20, which suggests greater genetic variation even among sister lines. The overall average of 17% heterogeneity was observed in the panel indicated the need for further inbreeding in the high heterogeneous genotypes. The mean nucleotide diversity and frequency of polymorphic sites observed in the panel were 0.28 and 0.02, respectively. The model-based population structure, principal component analysis, and phylogenetic analysis revealed three to six groups with no clear patterns of clustering by centers-wise breeding lines, types of corn, kernel characteristics, maturity, plant height, and ear placement. However, genotypes were grouped partially based on their source germplasm from where they derived.

This chapter presents the status of molecular breeding, especially marker-assisted backcross breeding (MABB), followed in each of the nutritional traits of maize. It focuses on breeding and improvement of protein quality, lysine and tryptophan, provitamin A, vitamin E, phytate, glycaemic index, amylose, and biofortification of maize for human and animal use.