Role of Vitamin B6 as an antioxidant during plant-microbe interactions

在病原体攻击后，植物最快速的防御反应之一是所谓的氧化爆发，这是在试图入侵的部位产生活性氧（ROS）。维生素B6 （VB6）是多种代谢酶的重要辅助因子，是一种有效的抗氧化剂，在植物发育过程和逆境反应中起着重要作用。然而，对其在植物抗土传病原菌侵染中的作用知之甚少。Brachypodium distachyon （Bd）现已被建立为禾草基因组学和基因发现的模型系统，并越来越多地用作谷物疾病的模型。茄枯丝核菌AG-8引起小麦根腐病和苗期前干枯病，这是全球谷物产区的两大限制产量的病害。所有已知的小麦和大麦品种，包括那些对锈病和其他病原体具有抗性的品种，都容易受到枯丝核菌AG-8的影响，而缺乏对根丝核菌的控制是直接播种广泛采用的主要障碍。短柄植物系被土壤传播的植物病原菌R. solani AG-8感染，并表现出与作物寄主（小麦）相似的症状。因此，对Brachyodium-R的VB6增强系进行了研究。茄属植物的相互作用有望提高我们对疾病抗性的理解，从而产生茄属植物抗性品系。在本研究中，我们通过对Bd系VB6生物合成基因的功能分析，探讨VB6在对茄蚜的防御反应中所起的作用。该提案将深入了解VB6在植物对病原体的反应中的作用及其作为抗氧化剂的作用，并了解VB6在保护病原体免受氧化应激中的作用。方法：通过一系列的实验，将生成过表达（OX） VB6基因的Bd转基因品系，以证明增强维生素B6含量的OX品系对氧化应激的耐受性增强，并且比野生品系对茄蚜感染或百草枯（ROS诱诱剂）的易感程度降低。此外，我们将探索转录组和代谢组水平的全细胞过程是如何受到影响的，因为预期具有增强或减少VB6基因的Bd系的初级代谢会发生广泛变化。预期意义：在过表达VB6编码基因的Bd植物中发现对茄枯病抗性的数量变化，将有助于抗性品系的选择。培育具有更高生物利用度的VB6维生素水平和更好的通用性状（如对真菌病原体引起的氧化应激的耐受性）的作物是改善营养和粮食安全的宝贵工具。HQP培训：5名研究生和一名PDF将接受“组学”学科、生物信息学和植物-微生物相互作用方面的培训。O

Summary of ProSummary of Proposal-2500 One of the most rapid plant defense reactions after pathogen attack is the so-called oxidative burst, which constitutes the production of reactive oxygen species (ROS) at the site of attempted invasion. Vitamin B6 (VB6), an essential cofactor for numerous metabolic enzymes, is a potent antioxidant and plays important roles in developmental process and plant stress responses. However, little is known about its function in plant disease resistance response against soilborne pathogen infections. Brachypodium distachyon (Bd) is now established as the model system for grass genomics and gene discovery and is increasingly used as the model for cereal disease. Rhizoctonia solani AG-8 causes rhizoctonia root rot and pre-emergence damping-off (aka barepatch) of wheat and barely, two major yield-limiting diseases in cereal production regions worldwide. All known cultivars of wheat and barley, including those having resistance to rusts and other pathogens, are susceptible to R. solani AG-8 and lack of control of Rhizoctonia poses a major barrier to the widespread adoption of direct seeding. Brachypodium lines are infected by the soilborne plant pathogen R. solani AG-8, and develop similar symptoms to the crop host (wheat). Thus, the study of enhanced VB6 lines of Brachyodium-R. solani interactions holds promise to improve our understanding of disease resistance and hence generation of R. solani resistant lines. In the present proposal we explore the involvement of VB6 in defense response against the R. solani through functional analysis of VB6 biosynthetic genes in Bd lines. The proposal will provide insight into the effect of the VB6 on plant response to pathogens and its role as an antioxidant, and also to understand the role of VB6 in the protection of the pathogen against oxidative stress. Approach: Bd transgenic lines overexpressing (OX) VB6 genes followed by a series of experiments will be generated in order to provide evidence that enhanced vitamin B6 content in OX lines have increased tolerance to oxidative stress and are less susceptible than WT lines to R. solani infections or to paraquat (ROS inducer). Also, we will explore how whole-cellular processes at the transcriptome and metabolome levels are affected since broad changes of the primary metabolism of Bd lines with enhanced or reduced VB6 genes are anticipated. Expected significance: Finding quantitative variation in resistance to R. solani in Bd plants overexpressing VB6 encoding genes would allow selection of resistant lines. The generation of crops combining enhanced levels of bioavailable VB6 vitamers and better generic traits such as tolerance to oxidative stress caused by fungal pathogens represent a valuable tool to improve nutrition and food security. HQP training: 5 graduate students and a PDF will be trained in `omics' disciplines, bioinformatics and plant-microbe interactions. O