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ABSTRACT Calmodulin, a highly conserved calcium‐binding protein, plays a crucial role in response to salt stress. Previous studies investigated sequence and function of calmodulin members in some plants, but their roles in rice have not been fully elucidated. Three OsCaM1 genes namely OsCaM1‐1/2/3 encode the same OsCaM1 protein. Here, we found that OsCaM1‐1 had significantly higher expression than the other two genes under salt stress. After 4 weeks of exposure to 75 mM NaCl, OsCaM1‐1 overexpressed mutants showed higher salt tolerance, while knocked‐out mutants exhibited lower salt tolerance, compared to the wild type. Moreover, the oscam1‐1 mutants had higher Na+ concentration and Na+/K+ ratio in both shoots and roots, less instantaneous K+ and Ca2+ fluxes in roots, compared to wild type under salt stress, indicating the involvement of OsCaM1‐1 in regulation of Na+ and K+ homoeostasis via Ca2+ signal. RNA‐seq analysis identified 452 differentially expressed genes (DEGs) regulated by OsCaM1‐1 and salt stress, and they were mainly enriched in nucleus DNA‐binding activities, including ABI5, WRKY76, WRKY48 and bHLH120 transcription factors. Knockout of OsCaM1‐1 also modulated the expression of Na+ transporters, including HKT1;1, HKT1;5, SOS1, NHX1 and NHX4. In conclusion, OsCaM1‐1 positively regulates salt tolerance in rice through mediating ion homoeostasis. [ABSTRACT FROM AUTHOR]

Salt stress is one of the major environmental restricts for crop production and food safety. Barley (Hordeum vulgare L.) is the most salt-tolerant cereal crop, which could be the pioneer for shifting agricultural crop production to marginal saline lands. However, probably due to high genetic complexity of salinity tolerance trait, the progress in the identification of salt-tolerant locus or genes of barley roots moves slowly. Here, we determined physiological and ionic changes in mini-core barley accessions under salt conditions. Na + content was lower in whole-plant but higher in roots of the salt tolerant genotypes than sensitive ones under salt stress. Genome-wide association study (GWAS) analysis identified 43 significant SNPs out of 12,564 SNPs and 215 candidate genes (P < 10 -3 ) in the roots of worldwide barley accessions, highly associated with root relative dry weight (RDW) and Na + content after hydroponic salinity in greenhouse and growth chamber. Meanwhile, transcriptomic analysis (RNA-Seq) identified 3217 differentially expression genes (DEGs) in barley roots induced by salt stress, mainly enriched in metabolism and transport processes. After GWAS and RNA-Seq integrating analysis, 39 DEGs were verified by qRT-PCR as salt-responding genes, including CYPs, LRR-KISS and CML genes, mostly related to the signal regulation. Taken together, current results provide genetic map-based genes or new locus useful for improving salt tolerance in crop and contributing to the utilization of saline soils., (Copyright © 2021 Elsevier Masson SAS. All rights reserved.)