Antisense suppression of phospholipase D alpha retards abscisic acid- and ethylene-promoted senescence of postharvest Arabidopsis leaves.
Fan, L.; Zheng SuQin; Wang XueMin;
Plant Cell Year: 1997 Vol: 9 Issue: 12 Pages: 2183-2196 Ref: 63 ref.
1997
บทคัดย่อ
Membrane disruption has been proposed to be a key event in plant senescence, and phospholipase D (PLD; EC 3.1.4.4) is thought to play an important role in membrane deterioration. Recently, three different PLDs from Arabidopsis were cloned and characterized. This paper examines the role of the most prevalent phospholipid-hydrolysing enzyme, PLD alpha , in membrane degradation and senescence in Arabidopsis. The expression of PLD alpha was suppressed by introducing a PLD alpha antisense cDNA fragment into Arabidopsis. When incubated with abscisic acid and ethylene, leaves detached from the PLD alpha -deficient transgenic plants showed a slower rate of senescence than did those from wild-type and transgenic control plants. The retardation of senescence was demonstrated by delayed leaf yellowing, lower ion leakage, greater photosynthetic activity and higher content of chlorophyll and phospholipids in the PLD alpha antisense leaves than in those of the wild type. Treatment of detached leaves with absc
isic acid and ethylene stimulated PLD alpha expression, as indicated by increases in PLD alpha mRNA, protein and activity. In the absence of abscisic acid and ethylene, however, detached leaves from the PLD alpha -deficient and wild-type plants showed a similar rate of senescence. In addition, the suppression of PLD alpha did not alter natural plant growth and development. These data suggest that PLD alpha is an important mediator in phytohormone-promoted senescence in detached leaves, but is not a direct promoter of natural senescence. The physiological relevance of these findings is discussed.