单 位：
山东农业大学园艺科学与工程学院/作物生物学国家重点实验室;山东农业大学化学与材料科学学院;山东大成农药有限公司
关键词：
黄瓜幼苗;NO3-胁迫;叶黄素循环;热耗散
摘 要：
【目的】揭示高浓度NO3-胁迫的黄瓜幼苗,在强光下对过剩光能的耗散机理。【方法】水培条件下,不同浓度的NO3-处理黄瓜幼苗7d,测定处理叶片与引入二硫苏糖醇(DTT)、抗坏血酸(AsA)的处理叶片中叶黄素循环各组分和非光化学猝灭(NPQ)的变化。【结果】NO3-浓度为14～98mmol·L-1处理的,黄瓜幼苗光合速率(Pn)与荧光参数的变化较小,差异不显著;但当NO3-处理浓度达140、182mmol·L-1时,幼苗光合速率、初始荧光(Fo)均显著低于对照,在较强光下NPQ、(A+Z)/(V+A+Z)%均高于对照;引入抑制剂DTT后,NPQ、(A+Z)/(V+A+Z)%均受到抑制;(A+Z)/(V+A+Z)%与NPQ变化趋势一致。NO3-浓度为140、182mmol·L-1处理的幼苗,由暗处突然转入1280μmol·m-2·s-1(PFD)强光下时,天线转化效率(Fv’/Fm’)、实际光化学效率(ΦPSⅡ)启动程度均低于对照,且启动减慢,NPQ启动程度均高于对照。对照、140、182mmol·L-1NO3-各处理,NPQ启动达最大值的时间分别约为6～9、6～9和15min;(A+Z)/(V+A+Z)%启动达最大值的时间分别约为15、15和24min;引入AsA后,三者NPQ达最大值时间都约为6～9min。【结论】当NO3-与强光共同胁迫时,黄瓜幼苗更易产生过剩激发能,依赖叶黄素循环的热耗散为耗散过剩激发能的主要方式;高浓度182mmol·L-1NO3-胁迫的黄瓜幼苗,叶黄素循环的启动呈减慢趋势。
译 名：
Thermal Dissipation and Trigging Depending on Xanthophyll Cycle in Cucumber Seedling Under NO_3~- Stress
作 者：
SU Xiu-rong1, WANG Xiu-feng2, YANG Feng-juan2, WANG Yu-gui3 (1College of Chemistry and Material Science, Shandong Agricultural University, Tai’an 271018, Shandong; 2College of Horticulture Science and Engineering, Shandong Agricultural University/State Key Laboratory of Crop Biology, Tai’an 271018, Shandong; 3Shandong Dacheng Pesticide Co., Ltd, Zibo 255000, Shandong)
关键词：
Cucumber seedling; NO3- stress; Xanthophyll cycle; Thermal dissipation trigging
摘 要：
【Objective】The purpose of this paper is to reveal the mechanism of excessive excited energy dissipation in cucumber seedling under NO3- stress. 【Method】Cucumber plants grown in nutrient solution with different NO3- concentrations for 7 d at hydroponics system, the changes of the xanthophyll cycle pigments and the non-photochemical quenching (NPQ) in the cucumber seedling leaves and DTT (1, 4-dithiothreitol) or AsA (ascorbate acid) treated leaves were investigated. 【Result】When the available NO3- concentration was low (14 to 98 mmol·L-1 NO3-) in the medium, compared to the cucumber seedling grown in the control, the changes of Pn (net photosynthetic rate) and the chlorophyll fluorescence parameters were not obvious and there were no significant difference. When the available NO3- was at higher level (140 to 182 mmol·L-1 NO3-) in the medium, the Pn and Fo (initial fluorescence in the absence of NPQ) significantly decreased. When the cucumber seedlings were stressed by both higher NO3- concentration and higher light intensity spontaneously, the NPQ and (A+Z)/(V+A+Z)% in cucumber seedling leaves were all increased. However, when DTT was applied, they were all decreased. The changing trend of NPQ consisted with that of (A+Z)/(V+A+Z)%. When the fully dark adapted cucumber seedlings stressed under 140 and 182 mmol·L-1 NO3- were suddenlyexposed to 1 280 μmol·m-2·s-1 (PFD:Photo flux density) strong light, the triggering degree of the Fv’/Fm’ (antenna efficiency at open centers in the presence of NPQ) and the ΦPSⅡ (actual PSⅡefficiency) were all decreased and the triggering process were slowed,the degree of NPQ triggering was bigger than that in the control. In the cucumber seedlings treated with 14, 140 and 182 mmol·L-1 NO3-, NPQ reached its maximum value at about 6-9 min, 6-9 min and 15 min, (A+Z)/(V+A+Z)% reached its maximum value at about 15 min, 15 min and 24 min, respectively. However, when AsA was applied, NPQ reached its maximum value all at about 6-9 min. 【Conclusion】When cucumber seedlings were treated under the stress of both higher NO3- concentration and high light intensity spontaneously, excessive energy was more easily produced, and thermal dissipation was mainly depending on xanthophyll cycle. Thermal dissipation depending on xanthophyll cycle was a main method to dissipate the excessive energy effectively. The triggering process of thermal dissipation depending on xanthophyll cycle was slowed in cucumber seedling leaves under 182 mmol·L-1. NO3- stress.
