Genome-wide characterization of NmrA-like proteins and the regulatory function of soybean GmNmrA6 in response to salt and oxidative stresses

Abstract

NmrA (nitrogen metabolic regulation A)-like proteins are a group of negative transcriptional regulators involved in nitrogen metabolism. However, their biological functions in response to abiotic stress in oil crops still remain largely unknown. In this work, 42 putative NmrA-like protein encoding genes (GmNmrAs) were obtained from soybean genome. Bioinformatic analyses indicated that they were unevenly anchored on 13 chromosomes, highly conserved in gene structure and motif composition, and have gone through 27 segmental duplication events. Gene expression analyses showed that all GmNmrAs were ubiquitously expressed with overlapped but differential expression patterns. Biological function analysis in transgenic soybean exhibited that overexpression of GmNmrA6 promoted the growth and enhanced the tolerance of salt and oxidative stress in transgenic plants. Further ion content and antioxidant enzyme activity analysis revealed that transgenic soybean accumulated less sodium, hydrogen peroxide and malondialdehyde in the leaves, accompanied with an increased catalase activity and up-regulated the expression level of stress-related marker gene. The observations in this study revealed the evolutionary relationships and structure of GmNmrAs in soybean and the crucial function of GmNmrA6 in plant growth and the tolerance of abiotic stresses.