摘要
以拟南芥野生型、G蛋白α亚基缺失突变体(gpa1-3,gpa1-4)及带有GFP-α-tubulin-6标记的gpa1突变体等为材料,利用药理学实验、激光共聚焦扫描显微镜观察、非损伤微测等方法研究在ABA诱导气孔运动的信息传递通路中,异三聚体G蛋白与微管骨架之间的功能关系,深入了解气孔运动机理.结果表明:gpa1突变体叶片蒸腾失水率高于野生型.气孔开度实验中,突变体对ABA抑制气孔开放作用不敏感,但微管特异性解聚剂Oryzalin在一定程度上可恢复其对ABA的响应.Ca^(2+)螯合剂BAPTA-AM与Oryzalin共同处理时,无论野生型还是突变体,ABA的作用均会被进一步削弱.激光共聚焦扫描显微镜下观察,ABA处理后,野生型保卫细胞中辐射状规则排布的微管比例急剧下降,解聚态微管大幅度增加;gpa1突变体没有出现如此明显的动态转换,仍多停滞在聚合态.ABA与BAPTA-AM共同处理,野生型植株不同微管排布类型的保卫细胞所占比例随之发生显著改变,gpa1突变体无明显变化.非损伤微测实验发现,突变体中ABA抑制光下保卫细胞Ca^(2+)外流作用不明显,但再加以微管解聚剂Oryzalin处理,Ca^(2+)外流即明显下降.以上结果显示,在G蛋白介导的ABA抑制气孔开放信号通路中,下游有保卫细胞微管骨架和Ca^(2+)的共同参与.
Stomata, formed by a pair of specialized guard cells, are present on the epidermis of most plant leaves. The regulation of stomatal apertures controls the exchange of moisture and gas between plants and the environment, and balances the carbon dioxide（CO2） entry into the plant for photosynthesis with water loss via transpiration. G-protein, a ubiquitous signaling molecule in eukaryotic cells, is an indispensable participator in the mechanism of stomatal movement. It was widely recognized that G-protein α subunit（GPA1） can regulate a majority of signals during stomatal movement, such as Ca^（2＋）, reactive oxygen species（ROS）, H2 O2, ethylene, and so on. On the other hand, guard cell microtubule（MT） dynamics play a comparably critical role in regulating stomatal movement, and MTs rearrangement has been observed in stomatal responses to a variety of stimuli, like light, dark, nitric oxide（NO）. Both heterotrimeric G-protein and MTs are essential for abscisic acid（ABA） signaling in guard cells, but whether and how these two signaling components work together is poorly understood. Here, the interplay between MTs and G-protein during ABA-induced stomatal movement was investigated in Arabidopsis thaliana. It was found that the heterotrimeric G-protein α subunit mutant, gpa1, had a significantly higher water loss ratio than the wild type under the same conditions. Stomatal bioassay analyses revealed that guard cell sensitivity to ABA was attenuated in gpa1, and the mutant＇s ABA-insensitive phenotype could be partially restored by Oryzalin, an MT-specific inhibitor. However, exogenously applied Ca^（2＋） chelator BAPTA-AM together with Oryzalin impaired the inhibition of stomatal opening by ABA. These results suggest that both MTs dynamics and Ca^（2＋） flux may participate in the process of G-protein-mediated regulation of ABA-induced stomatal movement. Confocal microscopic images showed that after ABA treatment, MTs arrays in wild type underwent rapid disruption from radial arrays
出处
《科学通报》
EI
CAS
CSCD
北大核心
2017年第32期3757-3767,共11页
Chinese Science Bulletin
基金
国家自然科学基金(31470011)资助
