Microsatellite marker-based genetic diversity analyses of novel maize inbreds possessing rare allele of β-carotene hydroxylase (crtRB1) for their utilization in β-carotene enrichment

Abstract

Vitamin A deficiency caused by insufficient intake of β-carotene has emerged as one of the most important problems afflicting people worldwide. Traditional yellow maize is predominated by lutein and zeaxanthin; but contains low β-carotene par below the daily requirement for humans. A natural variant of crtRB1 allele increases β-carotene in kernel by blocking its conversion to zeaxanthin. In the present study, genetic diversity analyses were carried out among 24 diverse maize inbreds possessing rare allele of crtRB1. The mean β-carotene among the inbreds was 9.3 μg/g, with 14 inbreds having 9.1-18.8 μg/g. Among the inbreds of exotic origin, HP704-23, HP704-22, HP467-15, HP465-41 and HP467-20 were promising with high β-carotene. In case of inbreds developed in India, VQL-2-PV, VQL1-PV, V345-PV, V335-PV, HKI161-PV, MGU-PV-2, HKI1105-PV, HKI323-PV and MGU-PV-3 were identified to possess high kernel β-carotene. These inbreds with rare allele of crtRB1 are unique germplasm and therefore holds immense promise in the biofortification programme worldwide. Molecular profiling of these inbreds using 65 SSRs distributed throughout the genome generated 268 alleles with a mean of 4.12 alleles per locus. The polymorphism information content varied from 0.21 to 0.82 with a mean of 0.58. The study detected 12 each of unique and rare alleles. Genetic dissimilarity ranged from 0.40 to 0.94 with an average of 0.79. Cluster analyses grouped 24 genotypes into four major clusters, and principal coordinate analysis depicted the diverse nature of the genotypes consistent with their pedigree. The study identified potential hybrid combinations for higher β-carotene that can be directly utilized in the biofortification programme.

Microsatellite-based genetic diversity analyses of sugary1-, shrunken2- and double mutant- sweet corn inbreds for their utilization in breeding programme

“…The PIC value in fact, depends upon the germplasm that was under investigation. Closely related lines would express lower PIC, whereas genetically diverse lines exhibit higher PIC values (Choudhary et al 2015;Muthusamy et al 2015). The mean PIC obtained in the present study is higher than earlier findings (Jun et al 2012;Lopes et al 2015).…”

“…Also a total of 12 (5.63%) rare alleles were also identified, of which bnlg1113, bnlg1162, bnlg1621, phi077, bnlg1740, bnlg1191, umc1296, bnlg2191, umc1335 and phi314704 produced one rare allele each, and dupssr34 generated two rare alleles. Occurrence of unique-and rarealleles depends upon the number of genotypes analysed and type of SSR markers used in the study, and earlier studies have reported the occurrence of unique and rare alleles in maize inbreds differing for various quality traits (Sivaranjani et al 2014;Choudhary et al 2015;Muthusamy et al 2015).…”

“…Some of the cryptic genetic variation at DNA levels may continue to exist, which segregates even after repeated generations of selfing and maintains the heterozygosity in the inbreds . This could also be due to mutation at specific SSR loci or non-specific amplification, where similar sequences in different genomic region get amplified due to duplications in the genome (Choudhary et al 2015). Inbreds developed through doubled haploid (DH) technology are completely homozygous for all the loci and this system is getting popular as it requires only one to two seasons.…”

Molecular characterization of endosperm and amino acids modifications among quality protein maize inbreds

“…This could be attributed to residual heterozygosity where certain loci tend to stay in heterozygous condition regardless of repeated cycles of selfing over many generations (Choudhary et al. , Muthusamy et al. ).…”

Genetic analyses of kernel carotenoids in novel maize genotypes possessing rare allele of β-carotene hydroxylase gene

“…Large-scale screening of Indian maize germplasm has led to identification of inbred lines with favourable allele of crtRB1 (Muthusamy et al 2015c). The allele has been found to be present in extremely low frequency, thus the inbreds with favourable-crtRB1 allele are novel possessing great promise in maize biofortification programme (Choudhary et al 2015).…”