Genome-wide identification of potassium channels in maize showed evolutionary patterns and variable functional responses to abiotic stresses

Abstract

Potassium (K) channels are essential components of plant biology, mediating not only K ion (K⁺) homeostasis but also regulating several physiological processes and stress tolerance. In the current investigation, we identified 27 K⁺ channels in maize and deciphered the evolution and divergence pattern with four monocots and five dicot species. Chromosomal localization and expansion of K⁺ channel genes showed uneven distribution and were independent of genome size. The dispersed duplication is the major force in expanding K⁺ channels in the target genomes. The mean Ka/Ks ratio of <0.5 in paralogs and orthologs indicates horizontal and vertical expansions of K⁺ channel genes under strong purifying selection. The one-to-one K⁺ channel orthologs were prominent among the closely related species, with higher synteny between maize and the rest of the monocots. Comprehensive K⁺ channels promoter analysis revealed various cis-regulatory elements mediating stress tolerance with the predominance of MYB and STRE binding sites. The regulatory network showed AP2-EREBP TFs, miR164 and miR399 are prominent regulatory elements of K⁺ channels. The qRT-PCR analysis of K⁺ channels and regulatory miRNAs showed significant expressions in response to drought and waterlogging stresses. The present study expanded the knowledge on K⁺ channels in maize and will serve as a basis for an in-depth functional analysis.

Keywords: Abiotic stress; Evolution; Expression; K(+) channels; Maize; Regulatory networks.