Comprehensive analysis of the oligopeptide transporter gene family in maize: Genome-wide identification, structural characterization, and stress-responsive expression

Abstract

Oligopeptide transporter (OPT) proteins are integral proteins in cell membranes that perform a crucial role in cellular metal homeostasis, mineral uptake, transport of small peptides and abiotic stress tolerance. Hence, in-depth evolutionary, structural, molecular and expression analysis could guide in exploring the mechanism of how these transporters contribute to nutrient balance and abiotic stress tolerance in maize. Following a series of bioinformatic analyses, eight OPTs in maize were identified. These transporters showed significant variations in molecular weight, and have one to five introns, 11 to 15 motifs, 11 to 18 transmembrane domains, multiple beta-strands, multiple alpha and transmembrane helices. ZmOPT1, 5, and 6 are plasma membranes and the rest are endoplasmic reticulum localized. All ZmOPTs are distributed in six different chromosomes having significant phytohormone-responsive cis-elements might be due to their great roles in hormonal regulation in maize. The significant transport activity of these transporters plays a great role in biological processes, cellular components and molecular functions in maize during gene ontology analysis. Co-expression of five genes among eight OPTs with 56 genes might be due to their great role in regulating other genes in multiple signaling pathways or vice-versa. Significant tissue-specific and drought, salinity, nitrogen starvation, and heat stress induced in silico expression following real time PCR validation of ZmOPT1, 7, and 8 genes might guide to elucidate the potential roles of these transporters in specific tissues and abiotic stress tolerance. Hence, the findings of the research might guide plant biologists to develop new varieties of maize having higher efficiency of peptide and metal ion transport, balance, and abiotic stress tolerance. Findings of these structural and expression analyzes might guide the plant biologist for single transgenesis, or developing and transforming programming-based synthetic genetic circuits in maize for advancing research in peptide transport, metal hemostasis, and increasing abiotic stress tolerance in maize.