Modulation of dehydration tolerance in soybean seedlings. Dehydrin Mat1 is induced by dehydration but not by abscisic acid.

摘要

Two-day-old soyabean (Glycine max) cv. Williams 82 seedlings subjected to rapid dehydration began to lose the ability to recover when the relative water content of the plant decreased below 60%. The expanded cells of the hypocotyl appeared more susceptible to dehydration-induced damage than did cells in the hypocotyl zone of cell growth. Pretreatment of seedlings prior to rapid dehydration with non-lethal water deficit or exogenous abscisic acid (ABA) shifted this viability threshold to progressively lower relative water contents, indicating the acquisition of increased dehydration tolerance. Increased tolerance was associated with osmotic adjustment in the hypocotyl zone of cell growth and with increases in soyabean dehydrin Mat1 mRNA levels. Theaccumulation of Mat1 mRNA was dehydration dependent but insensitive to ABA. It was concluded that induction of Mat1 mRNA accumulation by dehydration but not by ABA makes it an unusual member of the dehydrin family.