NO对He-Ne激光和增强UV-B辐射小麦幼苗气孔运动的作用机理研究

Mechanism of Action of Nitric Oxide on Stomatal Movement in Wheat Seedlings Exposed to Enhanced Ultraviolet-B Radiation and Irradiated by He-Ne laser

为探讨NO对He-Ne激光和增强UV-B辐射小麦(Triticum aestivuml)气孔运动的作用机理,采用低剂量(5 mW.mm-2)He-Ne激光和增强(10.08 kJ.m-2.d-1)UV-B辐射并结合药理学实验和激光共聚焦显微技术,对ML7113小麦的叶片及表皮条进行不同的处理,结果显示:(1)UV-B辐射既可诱导小麦叶片气孔关闭,又能够明显增加气孔保卫细胞和叶片的NO水平,且NO清除剂明显抑制了UV-B辐射诱导的小麦叶片气孔关闭,同时气孔保卫细胞和叶片内的NO含量明显减少。(2)一氧化氮合酶(NOS)抑制剂L-NAME对经UV-B辐射诱导的小麦幼苗气孔开度及保卫细胞和叶片内NO含量的抑制程度明显大于硝酸还原酶(NR)抑制剂NaN3对其的抑制程度,说明一氧化氮合酶(NOS)合成途径是小麦叶片经UV-B辐射后NO的主要产生途径。(3)就气孔开度而言,L>CK>BL>B。就小麦叶片及保卫细胞内NO含量而言,B>BL>CK>L。就硝酸还原酶(NR)和一氧化氮合酶(NOS)的活性而言,B组NR活性最低,NOS活性最高,L组NR活性最高,NOS活性最低。表明经He-Ne激光和增强UV-B辐射诱导的小麦气孔开度的变化确实与保卫细胞及叶片中NO含量的多少有关,气孔开度的减小及增大对应于NO含量的增多或减少,同时进一步证实了小麦叶片经He-Ne激光单独辐照后,NO的主要合成途径也来源于NOS途径。

The seedlings of wheat（＇ML7113＇） were exposed to He-Ne laser irradiation（L） with 5 mW·mm-2 power density after enhanced UV-B radiation（10.08 kJ·m-2·d-1） to determine the mechanism of the action of nitric oxide on stomatal movement in wheat seedlings.The leaves and epidermal strips of wheat underwent different treatments by experiments for pharmacology and laser scanning confocal microscopy.The results showed that（1） Enhanced UV-B radiation not only induced stomatal closure,but also increased the levels of NO significantly in the guard cells and leaves of wheat.In addition,NO scavenger cPTIO obviously inhibited stomatal closure induced by UV-B radiation and the levels of NO evidently reduced in guard cells and leaves of wheat.（2） There were obvious differences in the effect of nitric oxide synthase（NOS） inhibitor L-NAME on stomatal aperture,NO content in guard cells and leaves of wheat exposed to enhanced UV-B radiation compared with nitrate reductase（NR） inhibitor NaN3.This suggested that nitric oxide synthase was the main way to produce NO in wheat leaves by UV-B radiation.（3） For stomatal aperture,LCKBLB.For the NO level,BBLCKL.For activity of NR and NOS,NR activity in the UV-B radiation treatment group was the lowest and He-Ne laser irradiation treatment group was the highest;however,NOS activity between B and L showed the opposite pattern compared with NR acti-vity.The stomatal opening changes induced by UV-B radiation and He-Ne laser irradiation were associated with high and low NO content in guard cells and leaves of wheat.Decreases and increases in stomatal aperture were consistent with increases and decreases in NO content.Furthermore,NO generation was the same as nitric oxide synthase in wheat leaves by He-Ne laser individual irradiation.