光温交叉处理对小麦紫黄质脱环氧化酶活性及其热耗散能力的影响

EFFECTS OF TEMPERATURE AND LIGHT TREATMENT ON VIOLAXAN-THIN DE-EPOXIDASE ACTIVITY AND XANTHOPHYLL CYCLE-DEPENDENT ENERGY DISSIPATION IN WHEAT LEAVES

为了探讨温度和光强是如何影响离体紫黄质脱环氧化酶(VDE)活性,阐明依赖叶黄素循环的热耗散与VDE活性关系,该文以小麦(Triticum aestivum)为材料,研究了不同光强(200、500、900和1200μmol·m–2·s–1)和不同温度(4、25、38和45℃)交叉处理对小麦叶片VDE活性以及依赖叶黄素循环热耗散能力的影响。结果表明:小麦叶片VDE活性在30℃最高,说明30℃是小麦叶片VDE体外条件下的最适温度;不同光强处理下小麦叶片VDE活性基本一致。与室温(25℃)处理的叶片相比,低温(4℃)处理的叶片VDE活力没有明显下降,而高温(45℃)处理则导致了叶片VDE活性急剧下降。小麦叶片热耗散(NPQ)以及依赖叶黄素循环的热耗散(qE)均随着处理光强的增加不断上升,而qE/NPQ则随光强增加略微下降,在1200μmol·m–2·s–1光强条件下qE/NPQ则急剧下降。该研究揭示VDE活性与依赖叶黄素循环热耗散能力的指标qE/NPQ的变化有一定的相关性,但不完全一致。并针对此问题进行了讨论。

Aims Our objective was to explore how temperature and light directly affect activity of violaxanthin de-epoxidase （VDE） in vitro and to clarify the relationship between VDE activity and xanthophyll cycle-dependant energy dissipation. Methods We investigated VDE activities and energy dissipation in wheat leaves treated with different temperatures （4, 25, 38 and 45 ℃） combined with different light intensities （200, 500, 900 and 1 200 μmol·m^-2·s^-1）. Important findings Maximum activity of VDE in wheat leaves appeared at 30 ℃, suggesting that this was the optimum temperature for VDE in vitro. Light intensity had no effects on VDE activity in wheat leaves in vitro. Compared with 25 ℃, 4℃ treatment exhibited no obvious effect on VDE activity; however, 38 ℃ treatment caused slight increase while 45 ℃ caused dramatic decrease in the VDE activity. With increasing light intensity, non-photochemical quenching （NPQ） and xanthophyll cycle-dependent energy dissipation （qE） increased significantly. However, the ratio qE/NPQ decreased slightly when the temperature increased from 4 ℃ to 38 ℃ and decreased significantly when the temperature was increased to 45 ℃. Under low and moderate light intensity, the VDE activity measured at treatment temperature was in agreement with the qE/NPQ, which is a measure of the capacity of xanthophyll cycle-dependent energy dissipation.