研究了活性氧在UV-B(280～320 nm)诱导的玉米(Zea mays)幼苗叶片乙烯合成中的作用。结果表明,UV-B促进了玉米幼苗活性氧和乙烯的产生;乙烯合成抑制剂氨氧乙烯基甘氨酸 (AVG)和氨氧乙酸(AOA)能明显减弱UV-B对玉米幼苗乙烯产生的诱导作用,但对活性氧(ROS)的 产生没有明显影响;ROS的清除剂不但能抑制UV-B诱导的 ROS的产生,而且还可以抑制UV_B诱导的乙烯的产生,但这种抑制作用可以被外源O2.-的供体所逆转。这说明,乙烯的积累不能作为UV-B胁迫下ROS的诱导的因素,相反,ROS的积累则导致了乙烯的积累;因此,ROS可能参与了UV-B胁迫诱导的乙烯的产生。质膜NADPH氧化酶的抑制剂二苯碘鎓(DPI)和H2O2的特异性清除剂过氧化氢酶（CAT）对UV-B胁迫诱导的乙烯积累 几乎没有影响， 这说明H2O2可能与UV-B诱导的玉米幼苗叶片乙烯的产生无关, 在UV-B诱导的玉米幼苗叶片乙烯的生物合成过程中O2.-起着很重要的作用,相关的O2.-不是由NADPH氧化酶催化产生的。
Aims Ethylene accumulation and oxidative stress are two common responses of plants to environmental stresses; however, little is known about their relationships. Our objective was to investigate the role of reactive oxygen specie s (ROS) in ethylene synthesis induced by UV-B radiation (280-320 nm) in leaves of maize (Zea mays).
Methods Lamps were suspended above and perpendicular to the plastic trays and filtered with 0.13-mm thick cellulose diacetate (transmission down to 290 nm) for UV-B irradiance. The desired UV-B irradiation was obtained by changing the distance between the lamps and the plastic trays. The levels of UV-B irradiation were 4.8 kJ•m-2•d-1.
Important findings UV-B radiation led to the generation of ROS and ethylene. The accumulation of ethylene induced by UV-B was not only inhibited by the scavengers of ROS, but also by aminoxyacetic acid (AOA) and 2-aminoethoxyvinlglycine (AVG), which are specific inhibitors of ethylene synthesis. The inhibition effect of ROS scavengers on UV-B-induced ethylene production was reversed by O2.- donors. Results indicated that the increase in ethylene production may not be the cause of the increase in ROS production under UV-B stress. In contrast, the increase of ROS led to the accumulation of ethylene.
Results suggested that ROS are involved in UV-B stress-induced ethylene accumulation. The accumulation of UV-B-induced ethylene was not affected by DPI, an inhibitor of NADPH oxidase and CAT, a specific scavenger of H2O2. Results suggested that the effect of H2O2 on UV-B-induced ethylene production in leaves of maize seedlings can be excluded, O2.- plays an important role in UV-B-induced ethylene synthesis in leaves of maize seedling s and O2.- serves as a potential mediator of ethylene production that the plant can sense the UV-B stress. The related ROS are not from plasma membrane NADPH oxidase. The source of ROS contributing to ethylene accumulation under UV-B stress is unknown.