Drought and salt stress tolerance of ozone-toleranttransgenic poplar with an antisense DNA for1-aminocyclopropane-1 -carboxylate synthase

摘要

We examined the drought and salt stress tolerance of transgenic poplar (Populus nigra var. italica Koehne) with an antisense DNA for1-aminocyclopropane-1 -carboxylate synthase (ACS). Our previous report had already revealed that this transgenic poplarhad higher ozone tolerance. Compared with the wild-type, drought-induced senescence and defoliation of mature leaves was ameliorated in the transgenic poplar. Under salt stress, the transgenic poplar showed less foliar injury and maintained a higher photosynthetic activity than the wild-type. The mature leaves showed induction of ethylene biosynthesis under drought and salt stresses, which was attenuated in the transgenic plants as observed under ozone stress. Although the expression of ACS gene in themature leaves was induced by both drought and salt stress, the level of induction was lower in the transgenic poplar than in the wild-type. Therefore, it is assumed that the ACS gene is responsible for the increase in ethylene biosynthesis under these stresses. These results suggest that down-regulation of the ACS gene by the introduction of an antisense DNA is effective in enhancing the tolerance of poplar to multiple stresses.