Calcium/calmodulin modulates salt responses by binding a novel interacting protein SAMS1 in peanut (Arachis hypogaea L.)

Abstract

The Ca2+/CaM signal transduction pathway helps plants adapt to environmental stress. However, our knowledge on the functional proteins of Ca2+/CaM pathway in peanut (Arachis hypogeae L.) remains limited. In the present study, a novel calmodulin 4 (CaM4)-binding protein S-adenosyl-methionine synthetase 1 (SAMS1) in peanut was identified using a yeast two-hybrid assay. Expression of AhSAMS1 was induced by Ca2+, ABA, and salt stress. To elucidate the function of AhSAMS1, physiological and phenotypic analyses were performed with wild-type and transgenic materials. Overexpression of AhSAMS1 increased spermidine and spermidine synthesis while decreased the contents of ethylene, thereby eliminating excessive reactive oxygen species (ROS) in transgenic lines under salt stress. AhSAMS1 reduced uptake of Na+ and leakage of K+ from mesophyll cells, and was less sensitive to salt stress during early seedling growth, in agreement with the induction of SOS and NHX genes Transcriptomics combined with epigenetic regulation uncovered relationships between differentially expressed genes and differentially methylated regions, which raised the salt tolerance and plants growth. Our findings support a model in which the role of AhSAMS1 in the ROS-dependent regulation of ion homeostasis was enhanced by Ca2+/CaM while AhSAMS1-induced methylation was regulated by CaM, thus providing a new strategy for increasing the tolerance of plants to salt stress.

Keywords

• AhCaM4
• AhSAMS1
• Protein interaction
• Polyamines
• Salt tolerance