Aoki Nozomi, Ishibashi Yushi, Kai Kyohei, Tomokiyo Reisa, Yuasa Takashi, Iwaya-Inoue Mari
Crop Science Laboratory, Faculty of Agriculture, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan.
Crop Science Laboratory, Faculty of Agriculture, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan.
J Plant Physiol. 2014 May 1;171(8):615-8. doi: 10.1016/j.jplph.2014.01.005. Epub 2014 Mar 20.
The cereal aleurone layer is a secretory tissue that produces enzymes to hydrolyze the starchy endosperm during germination. We recently demonstrated that reactive oxygen species (ROS), produced in response to gibberellins (GA), promoted GAMyb expression, which induces α-amylase expression in barley aleurone cells. On the other hand, ROS levels increase during programmed cell death (PCD) in barley aleurone cells, and GAMyb is involved in PCD of these cells. In this study, we investigated whether the ROS produced in response to GA regulate PCD directly by using mutants of Slender1 (SLN1), a DELLA protein that negatively regulates GA signaling. The wild-type, the sln1c mutant (which exhibits gibberellin-type signaling even in the absence of GA), and the Sln1d mutant (which is gibberellin-insensitive with respect to α-amylase production) all produced ROS in response to GA, suggesting that ROS production in aleurone cells in response to GA is independent of GA signaling through this DELLA protein. Exogenous GA promoted PCD in the wild-type. PCD in sln1c was induced even without exogenous GA (and so without induction of ROS), whereas PCD in Sln1d was not induced in the presence of exogenous GA, even though the ROS content increased significantly in response to GA. These results suggest that PCD in barley aleurone cells is not directly stimulated by ROS produced in response to GA but is regulated by GA signaling through DELLA protein.
谷物糊粉层是一种分泌组织，在种子萌发过程中产生酶以水解淀粉胚乳。我们最近证明，由赤霉素（GA）诱导产生的活性氧（ROS）促进了GAMyb的表达，而GAMyb又能诱导大麦糊粉层细胞中α-淀粉酶的表达。另一方面，在大麦糊粉层细胞的程序性细胞死亡（PCD）过程中ROS水平会升高，并且GAMyb参与了这些细胞的PCD过程。在本研究中，我们通过使用负调控GA信号传导的DELLA蛋白Slender1（SLN1）的突变体，来研究由GA诱导产生的ROS是否直接调节PCD。野生型、sln1c突变体（即使在没有GA的情况下也表现出赤霉素型信号传导）和Sln1d突变体（对α-淀粉酶产生不敏感）在响应GA时均产生ROS，这表明糊粉层细胞中响应GA产生ROS独立于通过该DELLA蛋白的GA信号传导。外源GA促进了野生型中的PCD。即使没有外源GA（因此没有ROS诱导），sln1c中的PCD也会被诱导，而在存在外源GA的情况下，Sln1d中的PCD并未被诱导，尽管其ROS含量因GA而显著增加。这些结果表明，大麦糊粉层细胞中的PCD不是由响应GA产生的ROS直接刺激的，而是由通过DELLA蛋白的GA信号传导调节的。
