Overexpression of TaCML20, a calmodulin-like gene, enhances water soluble carbohydrate accumulation and yield in wheat

Calcium (Ca2+) is a universal messenger that mediates intracellular responses to extracellular stimuli in living organisms. Calmodulin (CaM) and calmodulin-like (CML) proteins are the important Ca2+ sensors in plants that decode Ca2+-signatures to execute downstream intracellular level responses. Several studies indicate the interlinking of Ca2+ and sugar signaling in plants; however, no genes have been functionally characterized to provide molecular evidence. Our study found that expression of TaCML20 was significantly correlated with water soluble carbohydrate (WSC) concentrations in recombinant inbred lines in wheat. TaCML20 has four EF-hand motifs that may facilitate the binding of Ca2+. To explore the role of CML20, we generated TaCML20 overexpressing transgenic lines in wheat. These lines accumulated higher WSC concentrations in the shoots, and we also found a significantly increased transcript level of sucrose:sucrose-1-fructosyltransferase (1-SST) in the internodes compared with the control plants. In addition, TaCML20 overexpressing plants showed significantly increased tillers per plant and also increased about 19% of grain weight per plant compared with control plants. The results also suggested a role for TaCML20 in drought stress, as its transcripts significantly increased in the shoots of wild-type plants under water deficit. These results uncovered the role of CML20 in determining multiple traits in wheat.