Folate profiling and characterization of sub-tropically adapted maize inbreds using folate-metabolism related genes

Folates, also known as vitamin B9, are vital for the normal growth and development of humans. In this study, we assessed 48 specialty and biofortified maize inbred lines for folate content and characterized them using markers specific to 78 candidate genes governing folate metabolism. Folate content, measured as the sum of 5-formyl-tetrahydrofolate (5-FTHF) and 5-methyl-tetrahydrofolate (5-MTHF), varied widely from 21.4 to 98.0 μg/100g, with a mean of 55.7 μg/100 g. Analysis using 78 SSR markers indicated a high conservation of folate-related genes across the genotypes. A total of 116 alleles were detected with a mean of 2.27 alleles/locus (range: 2–5). Among the markers, Fo-SSR-17 had five alleles, showing the highest discriminating power. The mean polymorphism information content (PIC) was 0.36 with a range from 0.19 (Fo-SSR-62) to 0.59 (Fo-SSR-50). Diversity analysis grouped the 48 genotypes into three distinct clusters, with a dissimilarity coefficient ranging from 0.08 to 0.34 (mean: 0.22). Single marker analysis found four markers significantly associated with folate content. Further, the haplotype analysis identified Hap6 (ABBB), Hap8 (ABHB), and Hap5 (ABAA) as superior haplotypes exhibiting higher folate content with mean values of 87.6 μg/100 g, 83.7 μg/100 g and 79.5 μg/100 g, respectively. Identification of diverse high folate inbred lines of maize inbreds and superior haplotypes offers potential for use in maize folate biofortification programs. This is the first report on characterization using a candidate gene for folate accumulation in subtropical genetic background.