摘要
以典型的耐盐树木胡杨(Populus euphratica)为试验材料,研究叶片气体交换对初始盐胁迫的响应机制。在初始盐胁迫下,胡杨叶片ABA和CaM水平提高,叶片气孔导度、蒸腾速率和净光合速率相应迅速下降,表明ABA和Ca2+.CaM参与了胡杨盐诱导的气孔关闭。5mmol.L-1钨酸钠(ABA合成抑制剂)、10mmol.L-1EGTA(胞外Ca2+螯合剂)和5mmol.L-1 LaCl3(Ca2+通道抑制剂)处理胡杨根部,对照苗木叶片的EVAP、Gs和Pn未受到影响,却提高了盐处理苗木(50mmol.L-1NaCl,4h)的气体交换。结果显示,盐诱导内源ABA和CaM水平的提高导致了胡杨叶片的气孔关闭,这是因为:1)钨酸钠处理降低了盐处理苗木的ABA水平,增加了CaM的含量;2)EGTA或LaCl3处理显著降低了胡杨叶片的CaM水平,但ABA水平显著升高。此外,通过茎导入ABA来模拟盐诱导内源ABA水平的提高,发现茎部导入的ABA(10μmol.L-1)能使胡杨叶片ABA和CaM水平迅速升高,叶片Gs、EVAP和Pn相应迅速下降,而先于ABA导入的5mmol.L-1LaCl3或5mmol.L-1EGTA虽然提高了ABA的水平,但却显著降低了CaM水平,ABA诱导胡杨的气孔关闭也受到明显抑制。研究结果显示,钨酸钠、EGTA和LaCl3的使用,都能抑制盐诱导胡杨的气孔关闭,因此,在初始盐胁迫诱导胡杨气孔关闭的过程中,ABA和CaM很可能是共同作用:诱导胞质Ca2+水平升高,激活外向的K+通道和Cl-通道,诱导气孔关闭,从而降低经由蒸腾流进行的根冠盐离子运输。
In this study we investigated the response of leaf gas exchange to the initial salt stress in a salt-resistant woody species, Populus euphratica. Endogenous abscisic acid （ABA） and calmodulin （CAM） in P. euphratica leaves significantly increased after the onset of NaC1 treatment （50 mmol·L^-1 NaCl, 4 h）, and stomatal conductance （ Gs ）, unit transpiration rate （EVAP） and net photosynthetic rate （Pa） markedly declined correspondingly. Those changes suggested that the increased concentrations of ABA and CaM both were involved in the salt-caused stomatal closure. Gs, EVAP and P, in comrol plants were not changed after plants were subjected to 5 mmol·L^-1 tungstate （ sodium form） （ ABA synthesis inhibitor）, 10 mmol·L^-1 EGTA （extracellular calcium chelator） or 5 mmol·L^-1 LaCl3 （ calcium channel inhibitor） treatment, but leaf gas exchange of NaCl- stressed plants （50 mmol·L^-1 NaCl, 4 h ） increased significantly. Tungstate （sodium form） application decreased ABA synthesis, however increased CaM levels in the salt-stressed plants, in contrast, EGTA or LaCl3 treatment decreased CaM levels but increased ABA synthesis in stressed P. euphratica. Extraneous ABA was applied via xylem feeding to mimic the salt-induced elevation of ABA in P. euphratica leaves. ABA and CaM in P. euphratica leaves significantly increased after ABA application （10 μLmol·L^-1 ）, and Gs, EVAP and Pa correspondingly declined. The introduction of 5 mmol·L^-1 EGTA or 5 mmol·L^-1 LaCl prior to ABA-feeding decreased CaM levels and the inhibitory effect of ABA on leaf gas exchange significantly although ABA levels were increased. In general, application of tungstate （sodium form）, EGTA or LaCl exhibited an inhibitory effect on salt-induced stomatal closure. The results suggest that both ABA and CaM participate in the process of salt-caused stomatal closure and hence reduce the root-to-shoot salt transport via transpiration stream probably by inducing the increase of cytosol Ca^2＋ concentration and activating the outward K^＋ and Cl^ channels.
出处
《林业科学》
CAS
CSCD
北大核心
2008年第1期57-64,共8页
Scientia Silvae Sinicae
基金
国家自然科学基金重点项目(30430430)
863计划课题(2006AA10Z131)
全国高校优秀博士学位论文作者专项基金(200152)
高等学校优秀青年教师教学科研奖励计划(2002-323)联合资助
