Adel Zarei1, Greta Z. Chiu1, Guanghui Yu2, Christopher P. Trobacher1, Barry J. Shelp1
1Department of Plant Agriculture, University of Guelph, 50 Stone Road East, Guelph, ON, N1G 2W1, Canada
2College of Life Sciences; South Central University for Nationalities; 708 Minyuan Road Wuhan 430074 China
Tóm tắt
4-Aminobutyrate (GABA) is a nonproteinogenic amino acid that functions in stress tolerance and signaling. Here, we report that salinity stress and elevated GABA levels coincided with the induction of glutamate decarboxylase 4 (GAD4) expression in Arabidopsis thaliana (L.) Heynh. ecotype Col-0. In-silico and microarray analysis revealed the over-representation of binding sites for WRKY and MYB transcription factors in the GAD4 promoter, as well as their co-expression with GAD4. Transcript profiling of liquid culture-grown, wild-type plantlets subjected to salinity stress for up to two days confirmed that GAD4 expression is associated with the inducible co-expression of WRKY28, WRKY30, WRKY40, MYB2, MYB15, and MYB108, as well as calmodulin-like 37 and aluminum-activated malate transporter 2, suggesting the involvement of gene regulation, protein activation, and anion transport in GABA accumulation. Transcript profiling of shoots from soil-grown, wild-type plants and corresponding single and double GAD mutants subjected to two days of salinity stress suggests that the GABA accumulation could involve post-translational activation of pre-existing GAD1 and GAD2 by elevated cytosolic calmodulin, as well as induction of GAD4 expression.
