磷脂酶Dδ对拟南芥叶片衰老过程中内源ROS和激素含量的影响

活性氧（ROS）和植物激素是植物衰老过程中重要的内在或者外在的调控因子。我们发现，相对于离体诱导的衰老过程，在脱落酸（ABA）和乙烯（ethylene）促进的衰老过程中有较多的活性氧积累；在对拟南芥磷脂酶Dδ（PLDδ）缺失型突变体的研究中发现，与野生型相比，突变体在衰老过程中产生较少的活性氧。我们比较了上述两种基因型的离体叶片在离体、ABA和ethylene三种衰老处理下内源的ABA、茉莉酸甲酯（MeJA）、玉米素核苷（Zeatin Riboside, ZR）和吲哚乙酸（IAA）的含量变化，发现每一种激素对上述三种衰老处理的响应模式都很相似。在离体诱导的衰老中，两种基因型拟南芥的内源激素含量没有差异；而在ABA促进的衰老过程中，PLDδ缺失型突变体叶片中的MeJA的含量较低，ZR和IAA含量较高；在乙烯促进的衰老过程中，突变体中的ABA和MeJA的含量较低，ZR和IAA含量较高。上述内源激素的这种变化可能有助于延缓突变体的衰老。

The Effects of Phospholipase Dδ Suppression on the Responsesof ROS and Hormones to Artificial Leaf Senescence in Arabidopsis thanliana

The reactive oxygen species (ROS) and hormones can act as an important internal or external factor influencing plant senescence. In the present study, we found that suppression of phospholipase Dδ (PLDδ) attenuated ROS production during abscisic acid (ABA) and ethylene promoted leaf senescence. We also comparatively analyzed the content of endogenous hormones, ABA, methyl jasmonate (MeJA), indole 3 acetic acid (IAA), and total zeatin in detachment induced senescence leaves, exogenous ABA and ethylene promoted senescence in wild type and PLDδ knockout (PLDδ KO) Arabidopsis leaves. We found that the response patterns of the four endogenous hormones to the three senescence treatments were identical. In comparison with wild type, PLDδ KO plants showed higher ZR and IAA levels and lower MeJA content under ABA and higher ZR and IAA levels and lower ABA and MeJA content under ethylene. The results suggested that these hormones might contribute to retarding ABA and ethylene promoted senescence in PLDδ knockout Arabidopsis.