Coordinated activation of as-1-type elements and a tobacco glutathione S-transferase gene by auxins, salicylic acid, methyl-jasmonate and hydrogen peroxide
1996
Xiang, C.B. | Miao, Z.H. | Lam, E.
The molecular mechanism of signal transduction pathways which mediate the action of phytohormones are poorly understood. Recently, we and others have shown that the as-1 type cis-acting elements can respond to auxin and salicylic acid, two well-characterized signaling molecules in plants. In the present work, we have examined a comprehensive set of physiological and abiotic agents and found that auxin, salicylic acid and methyl-jasmonate are three effective inducers of the as-1-type elements in transgenic tobacco. Using a cell suspension culture containing a synthetic promoter-GUS fusion, we demonstrated rapid and sensitive induction of the as-1-type element by these phytohormones. Furthermore, a tobacco glutathione S-transferase gene, GNT35, that contains an as-1-type binding site in its promoter is also inducible by auxin, salicylic acid and methyl jasmonate with similar kinetics. As Ulmasov et al. have recently reported, we found that the as-1-type elements can also respond to weak/inactive analogues of auxin and salicylic acid. In addition, we show that hydrogen peroxide can also effectively activate the expression of GNT35 as well as the as-1-type element in a cell suspension culture, but not with whole seedlings. These results are discussed with respect to the possible mechanism(s) through which a single cis element may respond to a diverse array of molecules.
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