低温弱光条件下毒死蜱对黄瓜的毒性及油菜素内酯的调控作用

Toxic Effects of Chlorpyrifos on Cucumber and Brassinosteroid-Mediated Responses under the Conditions of Chilling Temperature and Low Light

农药在使用中可能对农作物产生药害作用,而在低温弱光的亚适宜条件下,设施作物对农药暴露的应激响应可能具有特殊性。同时,作为一种新型植物激素,油菜素内酯在亚适宜条件下是否能够缓解农药的药害作用的研究有限。以典型的设施作物黄瓜为受试生物,通过人工气候箱模拟低温弱光的亚适宜条件,在毒死蜱(浓度分别为0.3和1mmol·L-1)暴露1、3和7d后,以实时荧光定量PCR对黄瓜叶片中光合作用基因(psaB、psbA和rbcL)、抗氧化系统相关基因(cAPX、DHAR、GR、CAT和GPX)、防御和应激相关基因(PAL、HPL、ADC和HSP70)的转录水平进行检测,阐明其毒性效应。并对比24-表油菜素内酯的预处理组,探讨油菜素内酯如何调控作物对农药胁迫的响应。结果表明,在低温弱光条件下,毒死蜱暴露抑制了黄瓜叶片中上述大部分基因的转录,而24-表油菜素内酯预处理后其转录水平显著上升,表明24-表油菜素内酯可有效且持续地缓解毒死蜱的药害效应。

Many pesticides probably have phytotoxicity on exposed plants. However, there is little available information regarding the stress response of crops to pesticides in the greenhouse under suboptimal condition with chilling temperature and low light. Brassinosteroids are one of new type of plant hormone, their mitigating the toxicity of pesticide on crops under the suboptimal condition remain unclear. In this study, the transcriptional responses to chlorpyrifos in the leaves of cucumber （Cucumis sativus）, was studied under the condition of the chilling temperature and low light in the artificial climate incubators. Cucumber was treated with chlorpyrifos at two concentrations （0.3 and 1.0 mmol·L-1） and the leaves were sample after 1, 3 and 7 days of exposure. In order to reveal whether the brassinosteroid can alleviate the phytotoxicity, cucumber was pretreated with 24-epibrassinolide 24 h before chlorpyrifos-exposure. The transcriptional level of genes involved in photosynthesis （psaB, psbA and rbcL）, protection against oxidative stress （cAPX, DHAR, GR, CAT and GPX）, defense （PAL, HPL and ADC） and heat shock （HSP70） were determined using quantitative real-time PCR. The results showed that chlorpyrifos treatment significantly reduced the transcriptional level for most genes under the condition of the chilling temperature and low light. While the transcriptions were induced after 24-epibrassinolide pretreatment, demonstrating that the brassinosteroid could protect crops against the phytotoxicity of pesticides effectively and persistently.