Comprehensive identification and characterization of abiotic stress and hormone responsive glycosyl hydrolase family 1 genes in Medicago truncatula

beta-glucosidases (BGLUs) hydrolyze the beta-D-glycosidic bond with retention of anomeric configuration. BGLUs were associated with many aspects of plant physiological processes, in particular biotic and abiotic stresses through the activation of phytohormones and defense compounds. However, studies on systematic analysis of the stressor hormone-responsive BGLU genes in plant are still rare. In this study, total 51 BGLU genes of the glycoside hydmlase family 1 were identified in the genome of the model legume plant Medicago truncatula, and they were classified into five distinct clusters. Sequence alignments revealed several conserved and characteristic motifs among these MtBGLU proteins. Analyses of their putative signal peptides and N-glycosylation site suggested that the majority of MtBGLU members have dual targeting to the vacuole and/or chloroplast. Many regulatory elements possibly related with abiotic stresses and phytohormones were identified in MtBGLU genes. Moreover, Microarray and qPCR analyses showed that these MtBGLU genes exhibited distinct expression patterns in various tissues, and in response to different abiotic stress and hormonal treatments. Notably, MtBGLU21, MtBGLU22, MtBGLU28, and MtBGLU30 in cluster I were dramatically activated by NaCl, PEG, IAA, ABA, SA and GA3 treatments. Collectively, our genome-wide characterization, evolutionary analysis, and expression pattern analysis of MtBGLU genes suggested that BGLU genes play crucial roles in response to various abiotic stresses and hormonal cues in M. truncatula.

Automated summary

This study identified and classified 51 BGLU genes in the model legume plant Medicago truncatula, revealing their distinct expression patterns in response to various abiotic stresses and hormonal cues. The results suggest that BGLU genes play crucial roles in plant physiological processes by activating phytohormones and defense compounds in response to stressors. Further analysis indicated conserved motifs and dual targeting of MtBGLU proteins to vacuole and/or chloroplast, as well as identification of regulatory elements related to stress and phytohormones.