Expression of Phospholipase D during XXXX Leaf Senescence.

@entity34655 @entity2271 @entity5122 @entity9377 @entity4620 @entity19164 @entity29619
Membrane deterioration in plant senescence is commonly associated with progressive decreases in membrane phospholipid content. This study investigated the expression and regulation of @entity4620 ( @entity4620 ; EC 3.1.4.4) during senescence in @entity9377 ( @entity9377 . cv Hale) leaf discs. The rate of leaf senescence was accelerated by 50 [mu]M @entity2271 and was attenuated by 50 [mu]M cytokinin during incubation at 23[deg]C for up to 5 @entity29619 senescence was indicated by decreases in the content of total proteins, chlorophyll, and phospholipids. @entity4620 activity in both membrane-associated and cytosolic fractions showed a gradual increase in the absence of @entity34655 . @entity2271 stimulated an increase in membrane-associated @entity4620 and had little effect on the soluble form. On the other hand, @entity19164 retarded the increase in membrane-associated @entity4620 . Immunoblotting analysis using @entity4620 -specific antibodies revealed that the changes in @entity4620 activity were correlated with those of @entity4620 protein. Analysis of @entity4620 by nondenaturing PAGE showed the appearance of a @entity4620 structural variant, @entity4620 3, in @entity2271 -treated leaf discs. Northern blotting analysis using a @entity4620 cDNA probe revealed an increase in @entity4620 mRNA in senescing leaf discs. These data indicate complex mechanisms for the regulation of @entity4620 during senescence, which include increases in membrane-associated @entity4620 , differential expression of @entity4620 isoforms, and changes in amounts of @entity4620 protein and mRNA. Such controlled expression points to a role for @entity5122 and plant senescence.
