Genotypic-dependent alteration in transcriptional expression of various CAT isoenzyme genes in esl mutant rice and its relation to H2O2-induced leaf senescence
Genotypic-dependent alteration in transcriptional expression of various CAT isoenzyme genes in esl mutant rice and its relation to H2O2-induced leaf senescence
复制标题
esl突变体水稻各种CAT同工酶基因转录表达的基因型依赖性改变及其与H2O2诱导的叶片衰老的关系
DOI：
10.1007/s10725-013-9884-6
复制
发表时间：
2014-07-01
影响因子：
4.2
通讯作者：
Cheng, Fangmin
中科院分区：
文献类型：
--
作者：
Li, Zhaowei;Wang, Fubiao;Cheng, Fangmin
为了阐明H2 O2诱导的叶片衰老与CAT基因表达之间的复杂关系，以水稻早衰叶突变体（esl）和野生型为材料，研究了叶片衰老过程中H2 O2含量、丙二醛（MDA）积累、相对电导率和CAT基因转录本表达的基因型变化。以离体叶片为材料，研究了不同外源H2 O2和阿坝处理对3个CAT基因表达及衰老相关生理指标的影响。结果表明，esl突变体在叶片衰老初期H2 O2水平高于野生型，随后MDA积累急剧增加。随后，膜完整性遭到严重破坏，叶绿素含量迅速下降，加速了esl突变体的衰老症状，显著降低了结实率。3个CAT基因的表达与H2 O2诱导的水稻叶片衰老损伤之间的相关性具有亚型依赖性，其中CATA和CATB在叶片衰老过程中的表达量及其时间模式具有明显的基因型依赖性。CATA和CATB基因对外源H2 O2处理的响应也比CATC基因更敏感，说明CATA和CATB基因在H2 O2钝化水稻叶片衰老过程中的作用比CATC基因更重要。CATA表达对衰老水稻叶片中H2 O2清除的贡献在叶片衰老的初始阶段最为突出，在叶片衰老开始时观察到更高的水平，而CATB在esl旗叶中的表达与CATA相比达到峰值较晚，并且也负责执行和加速H2 O2失活，特别是在叶片衰老开始后。在H2 O2清除过程中，CATB表达与CATA表达部分重叠。CATC在水稻叶片中的表达时间模式与H2 O2诱导的叶片衰老关系不大，但CATC在水稻叶片和叶鞘中优先表达，且具有器官/组织特异性。外源阿坝处理可引起离体叶片中MDA积累和相对电导率的增加，同时H2 O2水平显著增加。然而，在外源阿坝处理下的三种CAT同工酶的表达与直接由H2 O2处理诱导的表达不同，这表明尽管阿坝诱导衰老叶片中H2 O2水平增加，但在叶片衰老过程中清除H2 O2积累的方式不同。
To clarify the intricate relationship of H2O2-induced leaf senescence with distinct CAT gene expression, the genotypic-dependent alteration in the temporal patterns of H2O2 content, malondialdehyde (MDA) accumulation, relative conductivity, and the transcript expression of three CAT isoform genes during leaf senescence was investigated using two rice genotypes, namely, the early senescence leaf (esl) mutant and its wild type. Detached leaf segments were used to examine the effects of different exogenous H2O2 and ABA treatments on the expression of three CAT genes and other senescence-related physiological parameters. The results showed that the esl mutant had higher H2O2 level than its wild type at the initial phase of leaf senescence, which was followed by a sharp increase in MDA accumulation. Then, membrane integrity was severely destroyed and chlorophyll content decreased rapidly, which accelerated the senescence symptoms and significantly decreased the seed-setting rate in the esl mutant. The association of expression of the three CAT genes with rice leaf senescence lesions induced by H2O2 was isoform dependent, and the CATA and CATB expression exhibited remarkable genotype-dependent variation in the amount of transcript and their temporal pattern during leaf senescence. CATA and CATB also showed more sensitive response to exogenous H2O2 treatment compared with CATC, which suggests that CATA and CATB genes have a more important role than CATC in H2O2 inactivation of rice leaf senescence. The contribution of CATA expression to H2O2 scavenging in senescing rice leaves was most prominent at the initial stage of leaf senescence, with higher levels observed at the onset of leaf senescence, whereas CATB expression in esl flag leaf peaked later compared with CATA and was also responsible for the execution and acceleration of H2O2 inactivation particularly after the initiation of leaf senescence. CATB expression partially overlapped with CATA expression during H2O2 scavenging. For the CATC expression in rice leaves, its temporal pattern was poorly associated with H2O2-induced leaf senescence, but CATC was expressed preferentially in rice leaves and sheath and was involved in organ/tissue specificity. Exogenous ABA treatment can cause senescence-related increase in MDA accumulation and relative conductivity in the detached leaf segments, concomitant with a remarkable increase in H2O2 level. However, the expression of the three CAT isoforms under exogenous ABA treatment differed from those induced directly by H2O2 treatment, indicating the different ways for scavenging H2O2 accumulation during leaf senescence despite the increase in H2O2 level in senescing leaves induced by ABA.