Hatmi Saloua, Villaume Sandra, Trotel-Aziz Patricia, Barka Essaid A, Clément Christophe, Aziz Aziz
Induced Resistance and Plant Bioprotection - RIBP EA 4707, SFR Condorcet FR-CNRS 3417, UFR Sciences, University of Reims, Reims, France.
Front Plant Sci. 2018 Jul 11;9:1010. doi: 10.3389/fpls.2018.01010. eCollection 2018.
Abiotic factors inducing osmotic stress can affect plant immunity and resistance against pathogen attack. Although a number of studies have characterized grapevine responses to various forms of biotic and abiotic stresses, the relationships between osmotic stress response and susceptibility of mature berries to still remain unknown. In this study, we investigated the effects of osmotic stress and abscisic acid (ABA) on defense responses of mature grapevine berries before and after infection. We focused on the possible involvement of polyamines in the interaction between osmotic stress response and susceptibility to . We showed that osmotic stress induced by PEG or sucrose, and exogenous ABA induce transient but low defense responses, including weak expression of genes and phytoalexin synthesis in mature berries. This was accompanied by an upregulation of involved in ABA biosynthesis and a large production of free polyamines. However, osmotic stress followed by infection primed berries for enhanced accumulation of polyamines, but slowed down the defense responses and increased susceptibility to the pathogen. A weak increase of diamine- and polyamine-oxidase activities was also recorded in stressed berries, but declined after pathogen infection. The pretreatment of stressed berries with appropriate inhibitors of diamine- and polyamine-oxidases further increased polyamine level and greatly lowered defense responses, leading to higher susceptibility to . These results suggest that increased polyamine titer through low activation of their oxidative degradation in grape berries may contribute at least in part to the weakening of defense responses and subsequent disease susceptibility.
诱导渗透胁迫的非生物因素会影响植物免疫力和对病原体攻击的抗性。尽管许多研究已对葡萄对各种生物和非生物胁迫的反应进行了表征，但渗透胁迫反应与成熟浆果对病原体易感性之间的关系仍然未知。在本研究中，我们调查了渗透胁迫和脱落酸（ABA）对成熟葡萄浆果在感染病原体前后防御反应的影响。我们重点关注了多胺在渗透胁迫反应与对病原体易感性之间相互作用中可能的参与情况。我们发现，聚乙二醇（PEG）或蔗糖诱导的渗透胁迫以及外源ABA会诱导短暂但较弱的防御反应，包括成熟浆果中相关基因的微弱表达和植保素合成。这伴随着ABA生物合成相关基因的上调以及大量游离多胺的产生。然而，渗透胁迫后再感染病原体，会使浆果中多胺积累增强，但防御反应减缓且对病原体的易感性增加。在受胁迫的浆果中还记录到二胺氧化酶和多胺氧化酶活性有微弱增加，但在病原体感染后下降。用适当的二胺氧化酶和多胺氧化酶抑制剂对受胁迫的浆果进行预处理，会进一步提高多胺水平并大大降低防御反应，导致对病原体的易感性更高。这些结果表明，通过葡萄浆果中多胺氧化降解的低活性而增加的多胺滴度可能至少部分导致了防御反应的减弱以及随后的病害易感性。
