Virus Mediated Phloem Loading Involves the Suppression of Age Related Resistance

植物病毒在全世界范围内造成粮食、纤维和饲料作物的重大损失。 植物病毒引起这些疾病的能力通常与它们在宿主中系统移动的能力有关。 系统运动通常需要病毒进入植物的维管韧皮部。 作为植物的主要运输组织，韧皮部在多种分子的系统运动中起作用。 这些分子的运动在介导植物代谢、发育和病原体防御（包括与年龄相关的抗性）中具有至关重要的作用。 因此，要想成功，病毒必须克服这些防御才能篡夺这种运输组织。 不幸的是，控制这种形式的阻力的机制没有得到很好的研究。 本计画将以病毒-植物病理系统为模式，探讨ARR在防止病毒经由维管韧皮部系统性移动的调控与作用。 进一步的研究将确定病毒用于克服这种抗性并在整个植物中实现系统传播的机制。 由于与年龄相关的抗性影响广泛的病原体-宿主系统，预计这项研究将对许多农业上重要的作物产生广泛的影响。 其他更广泛的影响将涉及病毒学和植物生物学学科的整合，以培训研究生，本科生和高中生，目的是向这些学生介绍这些领域的各种职业机会。 利用烟草花叶病毒（TMV）-拟南芥系统，本发明的努力将利用TMV通过与表达生长素吲哚乙酸转录调节因子IAA 26的伴随细胞（CC）相互作用来重编程韧皮部特异性转录的能力。IAA蛋白是植物生长素应答系统的组成部分，在植物发育、代谢和防御等方面发挥重要作用。 TMV成功破坏IAA 26功能的能力显著增强了病毒在较老植物组织中的系统运动。韧皮部特异性转录研究表明IAA 26在调节与年龄相关抗性（ARR）相关的水杨酸和茉莉酸防御反应中的作用。因此，TMV重编程IAA 26指导的基因调控可能在抑制ARR中起作用。这种相互作用的鉴定代表了一种新的系统，从其中调查参与病毒韧皮部加载的分子机制。本研究的工作重点是鉴定IAA 26调控的CC表达的ARF转录因子，鉴定IAA 26调控下的CC基因，并表征IAA 26调控的CC基因对病毒韧皮部负载的影响。 结合这些研究将对我们理解韧皮部介导的病毒运动产生广泛的影响，这可能导致控制这些农业重要病原体的新策略。 其他更广泛的影响将向高中和本科生介绍植物生物学，病毒学和生物技术领域的各种研究机会，目的是鼓励这些学生考虑在这些领域进行高级培训。

Non-Technical ParagraphPlant viruses cause significant losses in food, fiber and forage crops throughout the world. The ability of plant viruses to cause these diseases is often linked to their ability to move systemically throughout their hosts. Systemic movement generally requires the virus to gain access to the plant's vascular phloem. As the plant's main transport tissue, phloem functions in the systemic movement of a diverse set of molecules. The movement of these molecules has a vital role in mediating plant metabolism, development and pathogen defenses, including age related resistance. Thus, to be successful viruses must overcome these defenses in order to usurp this transport tissue. Unfortunately, mechanisms controlling this form of resistance are not well studied. Efforts in this project will investigate the regulation and role of ARR in preventing virus systemic movement through the vascular phloem using a model virus - plant pathosystem. Additional studies will determine the mechanisms viruses use to overcome this resistance and achieve systemic spread throughout the plant. Since age-related resistance impacts a wide range of pathogen-host systems, it is anticipated that this study will have broad implications to many agriculturally important crops. Additional broader impacts will involve the integration of virology and plant biology disciplines for the training of graduate, undergraduate and high school students with the goal of introducing these students to the diverse career opportunities available in these fields. Technical ParagraphUsing a tobacco mosaic virus (TMV) - Arabidopsis system, efforts in this proposal will exploit the ability of TMV to reprogram phloem specific transcription through an interaction with the companion cell (CC) expressed auxin indole acetic acid transcription regulator IAA26. IAA proteins are components of the plant auxin response system and play essential roles in many aspects of plant development, metabolism and defense. The ability of TMV to successfully disrupt IAA26 function significantly enhances virus systemic movement in older plant tissues. Phloem specific transcriptional studies demonstrate a role for IAA26 in the regulation of salicylic and jasmonic acid defense responses that are associated with age related resistance (ARR). Thus, TMV reprograming of IAA26 directed gene regulation likely functions in the suppression of ARR. The identification of this interaction represents a novel system from which to investigate molecular mechanisms involved in virus phloem loading. Efforts in this proposal will focus on identifying the CC expressed ARF transcription factors modulated by IAA26, identify CC genes under the control of IAA26 regulation and characterize the impact of IAA26 regulated CC genes on virus phloem loading. Combined these studies will have broad impacts on our understanding of phloem-mediated virus movement that could result in new strategies to control these agriculturally important pathogens. Additional broader impacts will introduce high school and undergraduate students to the diverse research opportunities available in the fields of plant biology, virology and biotechnology with the goal of encouraging these students to consider advanced training in these areas.