Co-Authors:
Dewald, D.B., Dept. of Biochemistry and Biophysics, Texas A and M University, College Station, TX 77843, United States, Div. of Cell. and Molecular Medicine, Howard Hughes Medical Institute, University of California, San Diego, San Diego, CA 92093-0668, United States
Sadka, A., Dept. of Biochemistry and Biophysics, Texas A and M University, College Station, TX 77843, United States
Mullet, J.E., Dept. of Biochemistry and Biophysics, Texas A and M University, College Station, TX 77843, United States
Abstract:
We have shown that auxin represses soybean (Glycine max L.) vegetative storage protein gene (Vsp) expression in suspension-cultured cells and in leaves and petioles of excised trifoliates. The auxin analog naphthyleneacetic acid (NAA) at 10 μM strongly inhibited methyl jasmonate-induced Vsp expression in soybean suspension-cultured cells. Both indole-3-acetic acid and NAA inhibited methyl jasmonate- and wound-induced expression of the Vsp and LoxA in excised soybean trifoliate leaves and petioles. The less active auxin analog phenylacetic acid had less effect on methyl jasmonate- and wound-induced expression of these genes. Addition of cytokinin to alter the auxin:cytokinin ratio did not reverse auxin inhibition of Vsp expression. Transcription of β-glucuronidase (Gus) modulated by a methyl jasmonate-responsive domain derived from the VspB promoter was minimally influenced by auxin. In contrast, sucrose-induced expression of Gus mediated by a sucrose-responsive domain of the VspB promoter was strongly inhibited by NAA. We conclude that auxin inhibits Vsp mRNA accumulation, in part, by repressing sugar-mediated activation of Vsp expression.