Chill-induced inhibition of photosynthesis was alleviated by 24-epibrassinolide pretreatment in cucumber during chilling and subsequent recovery
Chill-induced inhibition of photosynthesis was alleviated by 24-epibrassinolide pretreatment in cucumber during chilling and subsequent recovery
复制标题
在寒冷和随后的恢复过程中，24-表油菜素内酯预处理可以减轻寒冷引起的光合作用抑制
DOI：
10.1007/s11099-010-0071-y
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发表时间：
2010-12-01
期刊：
影响因子：
2.7
通讯作者：
Zeng, Q. M.
中科院分区：
文献类型：
--
作者：
Hu, W. H.;Wu, Y.;Zeng, Q. M.
研究了外源24-表油菜素内酯(EBR)对黄瓜叶片气体交换、叶绿素荧光参数和抗氧化酶活性的影响，以探讨油菜素内酯(BRS)能否缓解冷害对黄瓜光合作用的抑制。黄瓜植株在弱光(12/8℃和100μ−2S−1PPFD)下冷藏3d，然后在常温和高光照(28/18℃和600μmolm−2S−1PPFD)下恢复6d。低温显著降低了黄瓜叶片的净光合速率(Pn)和气孔导度(GS)，提高了O2·−形成速率和过氧化氢及丙二醛含量，但不影响PSⅡ的最适量子效率(Fv/Fm)。低温还降低了PSⅡ光化学有效量子效率(ΦPS II)和光化学猝灭(QP)，但导致非光化学猝灭(NPQ)增加，超氧化物歧化酶和抗坏血酸过氧化物酶(APX)活性增加。强光照(600μmolm−2s−1)进一步加剧了冷藏后恢复第一天Pn、GS、ΦPSII和QP的下降，并促进了ROS的产生和积累。而强光照射可使Fv/Fm、NPQ、超氧化物歧化酶和APX活性在恢复期显著降低。在低温胁迫和随后的恢复期，EBR处理显著缓解了低温对光合作用的抑制，这主要是由于INGS、ΦPSⅡ、qP和NPQ显著增加所致。EBR处理也减少了ROS的产生和积累，提高了冷藏和后续恢复过程中的SOD和APX活性。这些结果表明，EBR处理主要通过提高气孔导度、叶片吸收光能的利用和耗散效率以及低温和恢复期ROS清除系统的活性来缓解光合作用的冷害，加快恢复速率。
To investigate whether brassinosteroids (BRs) could be used to alleviate chill-induced inhibition of photosynthesis in cucumber (Cucumis sativusL) during chilling and subsequent recovery, the effects of exogenously applied 24-epibrassinolide (EBR) on gas exchange, chlorophyll fluorescence parameters, and antioxidant enzyme activity were studied. Cucumber plants were exposed to chilling under low light (12/8°C and 100 μmol m−2s−1PPFD) for 3 days and then recovered under normal temperature and high irradiance (28/18°C and 600 μmol m−2s−1PPFD) for 6 days. Chilling significantly decreased the net photosynthetic rate (PN) and stomatal conductance (gs), and increased rate of O2·−formation and H2O2and malondialdehyde (MDA) content in cucumber leaves, but did not influence the optimal quantum yield of PSII (Fv/Fm). Chilling also decreased the effective quantum yield of PSII photochemistry (ΦPSII) and photochemical quenching (qP), but induced an increase in nonphotochemical quenching (NPQ), and the activities of superoxide dismutase (SOD) and ascorbate peroxidase (APX). High irradiance (600 μmol m−2s−1) further aggravated the decrease inPN,gs, ΦPSIIand qP, and enhanced the increase in reactive oxygen species (ROS) generation and accumulation in the first day of recovery after chilling. However, high irradiance induced a sharp decrease in Fv/Fmand NPQ, as well as the activities of SOD and APX on the first day of recovery. EBR pretreatment significantly alleviated chill-induced inhibition of photosynthesis during chilling stress and subsequent recovery period, which was mainly due to significant increases ings, ΦPSII, qPand NPQ. EBR pretreatment also reduced ROS generation and accumulation, and increased the activities of SOD and APX during chilling and subsequent recovery. Those results suggest that EBR pretreatment alleviates the chill reduction in photosynthesis and accelerated the recovery rate mainly by increasing of the stomatal conductance, the efficiency of utilization and dissipation of leaf absorbed light, and the activity of the ROS scavenging system during chilling and subsequent recovery period.