Alamin Alfatih, Jing Zhang, Ying Song, Sami Ullah Jan, Zi-Sheng Zhang, Jin-Qiu Xia, Zheng-Yi Zhang, Tahmina Nazish, Jie Wu, Ping-Xia Zhao, Cheng-Bin Xiang.

Plant Commun.; 2023 Mar 13; 4(2):100458. doi: 10.1016/j.xplc.2022.100458.

Abstract

Salt stress is a major constraint on plant growth and yield. Nitrogen (N) fertilizers are known to alleviate salt stress. However, the underlying molecular mechanisms remain unclear. Here, we show that nitrate-dependent salt tolerance is mediated by OsMADS27 in rice. The expression of OsMADS27 is specifically induced by nitrate. The salt-inducible expression of OsMADS27 is also nitrate dependent. OsMADS27 knockout mutants are more sensitive to salt stress than the wild type, whereas OsMADS27 overexpression lines are more tolerant. Transcriptomic analyses revealed that OsMADS27 upregulates the expression of a number of known stress-responsive genes as well as those involved in ion homeostasis and antioxidation. We demonstrate that OsMADS27 directly binds to the promoters of OsHKT1.1 and OsSPL7 to regulate their expression. Notably, OsMADS27-mediated salt tolerance is nitrate dependent and positively correlated with nitrate concentration. Our results reveal the role of nitrate-responsive OsMADS27 and its downstream target genes in salt tolerance, providing a molecular mechanism for the enhancement of salt tolerance by nitrogen fertilizers in rice. OsMADS27 overexpression increased grain yield under salt stress in the presence of sufficient nitrate, suggesting that OsMADS27 is a promising candidate for the improvement of salt tolerance in rice.

See https://pubmed.ncbi.nlm.nih.gov/36199247/

Figure 4 Transcriptomic analysis of differentially expressed genes (DEGs) affected by OsMADS27.

(A) Number of DEGs. Statistical data of DEGs in the (KO vs. WT)-control, (OE vs. WT)-control, (KO vs. WT)-salt, and (OE vs. WT)-salt comparisons.

(B) Venn diagram of DEGs in the (KO vs. WT)-control, (OE vs. WT)-control, (KO vs. WT)-salt, and (OE vs. WT)-salt comparisons. The numbers represent the total numbers of DEGs in different comparison groups.

(C) Hierarchical clustering analysis of N- and salt stress-related genes affected by OsMADS27 among the DEGs. The heatmap shows fold changes in the abundance of gene transcripts in different comparison groups.

(D) OsMADS27 broadly regulates genes involved in salt tolerance. Seven-day-old plants grown hydroponically on medium containing different N concentrations (0.02, 0.2, and 2 mM KNO₃) supplemented with either 0 mM NaCl or 150 mM NaCl were harvested for qRT‒PCR analyses of the indicated genes. Actin was used as an internal control. Different letters denote significant differences (P < 0.05) from Duncan’s multiple range tests.