Molecular Characterization and Haplotype Analysis of Low Phytic Acid-1 (lpa1) Gene Governing Accumulation of Kernel Phytic Acid in Subtropically-Adapted Maize

Abstract

Maize is an important food, feed, fodder and industrial crop in addition to being a valuable source of micronutrients. Phytic acid (PA), an anti-nutritional factor in maize, makes crucial minerals inaccessible to monogastric animals. The low phytic acid-1 (lpa1) gene located on chromosome-1S is 7292 bp long with 11 exons, and the recessive lpa1-1 allele reduces the accumulation of PA thereby enhances the bioavailability of essential minerals in maize kernels. Here, we characterized the full-length Lpa1 gene sequence in three mutants (lpa1-1) and seven wild-type (Lpa1) maize inbreds. Sequence analysis revealed 607 polymorphic sites across Lpa1 sequences, indicating wide variability for Lpa1 among the inbreds. Further, SNP from “C” to “T” differentiated wild-type and mutant-type alleles at 1432 amino acid position. Gene-based diversity among 48 diverse maize inbreds using 15 InDel markers revealed the formation of 42 distinct haplotypes; six of which (Hap6, Hap16, Hap17, Hap19 Hap27 and Hap31) were shared by more than one genotype. The number of exons in Lpa1 ranged from 11-19 among maize genotypes and 6-14 among 26 orthologues. Major functional motifs of Lpa1 detected were ATP-binding Cassette (ABC) transporter trans-membrane region and ABC transporter. Phylogenetic tree using nucleotide and protein sequences revealed a closer relationship of maize Lpa1 sequences with Sorghum bicolor, Panicum hallii, Setaria italica and S. viridis. This study offered newer insights into the understanding of the genetic diversity of the Lpa1 gene in maize and related crop-species, and information generated here would further help in exploiting the lpa1 mutant for the enhancement of nutritional value in maize kernels.