Soybean late embryogenesis abundant protein GmLEA4 interacts with GmCaM1, enhancing seed vigor in transgenic Arabidopsis under high temperature and humidity stress

Calmodulin (CaM) as a ubiquitous Ca2+-binding protein is involved in multiple signaling processes expressed in all the eukaryotic cells, while the late embryogenesis abundant (LEA) proteins are a large family of hydrophilic proteins that accumulate in developing seeds to ensure protection against water deficit stress. In our previous study, GmLEA4 was screened as a candidate GmCaM1-interacting protein by yeast two-hybrid assay while GmCaM1 was found to be highly related to the formation of seed vigor under high temperature and humidity (HTH) stress in soybean. In the present study, GmLEA4 was localized on the cell membrane and nucleus. The interaction between GmCaM1 and GmLEA4 was further confirmed by yeast two-hybrid assay, bimolecular fluorescence complementation (BiFC) and GST pull down. GmLEA4 and GmCaM1 showed higher expression levels in seeds than in other tissues and were involved in response to HTH stress. The overexpression of GmCaM1 and GmLEA4 in Arabidopsis raised the ROS scavenging ability in seeds and improved seed vitality under HTH stress. Our results indicated that GmLEA4 interacts with GmCaM1, maybe participating in seed vigor formation under HTH stress in soybean.