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

Vitamin A deficiency caused by insufficient intake of beta-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 beta-carotene par below the daily requirement for humans. A natural variant of crtRB1 allele increases beta-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 beta-carotene among the inbreds was 9.3 mu g/g, with 14 inbreds having 9.1-18.8 mu g/g. Among the inbreds of exotic origin, HP704-23, HP704-22, HP467-15, HP465-41 and HP467-20 were promising with high beta-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 beta-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 beta-carotene that can be directly utilized in the biofortification programme.