Department of Evolutionary Biology, Ecology and Environmental Sciences, Faculty of Biology, University of Barcelona, Avinguda Diagonal, 643, E-08028, Barcelona, Spain.
Institute of Biological, Environmental and Rural Sciences, Aberystwyth University, Gogerddan Campus, Aberystwyth, SY23 3EB, UK.
Plant Physiol Biochem. 2018 Jun;127:200-210. doi: 10.1016/j.plaphy.2018.03.033. Epub 2018 Mar 28.
Tocopherols are lipid-soluble antioxidants that contribute to plant resistance to abiotic stresses. However, it is still unknown to what extent alterations in tocopherol composition can affect the plant response to biotic stresses. The response to bacterial and fungal attack of the vte1 mutant of Arabidopsis thaliana, which lacks both α- and γ-tocopherol, was compared to that of the vte4 mutant (which lacks α- but accumulates γ-tocopherol) and the wild type (with accumulates α-tocopherol in leaves). Both mutants exhibited similar kinetics of cell death and resistance in response to Pseudomonas syringae. In contrast, both mutants exhibited delayed resistance when infected with Botrytis cinerea. Lipid and hormonal profiling was employed with the aim of assessing the underlying cause of this differential phenotype. Although an altered tocopherol composition in both mutants strongly influenced fatty acid composition, and strongly altered jasmonic acid and cytokinin contents upon infection with B. cinerea, differences between genotypes in these phytohormones were observed during late stages of infection only. By contrast, genotype-related effects on lipid peroxidation, as indicated by malondialdehyde accumulation, were observed early upon infection with B. cinerea. We conclude that an altered tocopherol composition in chloroplasts may negatively influence the plant response to biotic stress in Arabidopsis thaliana through changes in the membrane fatty acid composition, enhanced lipid peroxidation and delayed defence activation when challenged with B. cinerea.
生育酚是脂溶性抗氧化剂，有助于植物抵抗非生物胁迫。然而，生育酚组成的改变在多大程度上影响植物对生物胁迫的反应仍然未知。与缺乏α-和γ-生育酚的拟南芥 vte1 突变体相比，比较了缺乏α-但积累γ-生育酚的 vte4 突变体（积累α-生育酚在叶片中）和野生型（在叶片中积累α-生育酚）对细菌和真菌攻击的反应。两种突变体对丁香假单胞菌的反应都表现出相似的细胞死亡和抗性动力学。相比之下，两种突变体在感染灰葡萄孢时表现出延迟的抗性。采用脂质和激素分析方法，旨在评估这种差异表型的潜在原因。尽管两种突变体中改变的生育酚组成强烈影响脂肪酸组成，并且在感染灰葡萄孢时强烈改变茉莉酸和细胞分裂素含量，但在感染后期仅观察到这些植物激素在基因型之间存在差异。相比之下，感染灰葡萄孢后早期就观察到与基因型相关的脂质过氧化作用（如丙二醛积累）。我们得出结论，叶绿体中改变的生育酚组成可能通过改变膜脂肪酸组成、增强脂质过氧化作用以及在受到灰葡萄孢攻击时延迟防御激活，对拟南芥对生物胁迫的反应产生负面影响。
