ABA-Dependent Regulation of Calcium-Dependent Protein Kinase Gene in Cultivated and Wild Soybeans.

Calcium-dependent protein kinases (CDPKs) regulate plant development and stress responses. However, the interaction of these protein kinases with the abscisic acid (ABA) stress hormone signalling system has not been studied in detail. In , AtCPK1 plays an important role in the acclimation of plants to environmental stresses. Phylogenetic and molecular analyses showed that, among 50 isoforms of (L.) Merrill CDPKs, the GmCDPK27/GmCDPK48, GmCDPK5/GmCDPK24, and GmCDPK10/GmCDPK46 paralogous pairs were the isoforms most related to AtCDPK1. We investigated the expression of the corresponding six genes during treatment with cold, heat, and salt stress. Wild soybean was the most resistant to stresses, and among the three cultivars studied (Sfera, Hodgson, and Hefeng25), Sfera was close to the wild type in terms of resistance. and were the most responsive to stress treatments, especially in wild soybean, compared with cultivars. Among the studied isoforms, only expression increased after treatment with abscisic acid (ABA) in a dose- and time-dependent manner. Targeted LC-MS/MS analysis of endogenous ABA levels showed that wild soybean and Sfera had nearly twice the ABA content of Hodgson and Hefeng25. An analysis of the expression of marker genes involved in ABA biosynthesis showed that -gene-encoding 9-cis-epoxycarotenoid dioxygenase 1 is induced to the greatest extent in wild soybean and Sfera under salt, cold, and heat exposure. Our data established a correlation between the induction of and ABA biosynthesis genes. is an interesting target for genetic and bioengineering purposes and can be used for genetic editing, overexpression, or as a marker gene in soybean varieties growing under unfavourable conditions.