Recipient Organization
CORNELL UNIVERSITY
(N/A)
ITHACA,NY 14853
Performing Department
PLANT PATHOLOGY
Non Technical Summary
Plant viruses cause huge crop losses world wide, impacting the global economy and human nutrition. Identifying a common host regulator, which is essential for viral invasion of the plant, can lead to engineered broad-based resistance against most, and perhaps all plant viruses. Our discovery that SYTA, one of 5 synaptotagmins in Arabidopsis, regulates the cell-to-cell spread of distinct and unrelated plant viruses such as Geminiviruses in the Begomovirus subfamily (Cabbage leaf curl virus) and Tobamoviruses (Tobacco mosaic virus), suggests that SYTA is an essential key regulator of plant virus spread and invasion of the host. The purpose of our project is to examine whether SYTA alone, or in partnership with other SYTs, regulates the spread and disease potential of most, if not all, plant viruses. Beyond the agronomic impact of engineering disease-resistant plants, our studies are relevant to human health in that they can inform and accelerate studies of animal
synaptotagmins in cell-cell communication and development, and of mechanisms by which retroviruses redirect the endosomal machinery for virus maturation and exit from an infected cell. This research investigates the regulation of what seems to be a common pathway for transport between plant and animal cells. As such, it can impact public health by improving nutrition, providing knowledge about growth defects, and identifying novel ways to limit the spread of HIV and other retroviruses.
Animal Health Component
(N/A)
Research Effort Categories
Basic
100%
Applied
(N/A)
Developmental
(N/A)
Goals / Objectives
Plant virus movement proteins transport viral genomes across the cell wall by altering plasmodesmata, transwall pores that connect adjacent plant cells. Synaptotagmins, a multigene family thought to be exclusive to animals, are calcium (Ca2+) sensors that regulate synaptic vesicle exo/endocytosis. Our long term goal is to understand how synaptotagmins regulate virus movement and intercellular transport to control disease resistance, the spread of RNAi signals and cell fate. SYTA is 1 of 5 Arabidopsis synaptotagmins (SYT A-E). SYTA binds to the distinct movement proteins encoded by the Begomoviruses CaLCuV (CaLCuV MP) and SqLCV, and the Tobamovirus TMV (30K). We have shown that SYTA regulates both the formation of early endosomes and the cell-to-cell transport of CaLCuV MP and TMV 30K. We propose that SYTs regulate macromolecular trafficking to plasmodesmata via an endocytic recapture pathway, and potentially entry into and exit from the pore as well. We will use a
combination of transgenic plant studies and cell-based expression assays to investigate if the five Arabidopsis SYTs are key regulators of plant virus movement and intercellular transport.
Project Methods
Biochemical and infectivity studies, and a leaf-based cell trafficking assay will examine if SYTA alone regulates the cell-to-cell movement of most viruses, or whether other SYTs are also involved, either independent of or partnering with SYTA. The roles of SYTs B, C, D and E in vesicle trafficking will be defined by immune localization, and the use of cell- and leaf-based secretion assays. Multiphoton imaging of SYTA itself, or with CaLCuV MP and TMV 30K, or with SYTs B, C, D and E, will show how SYTA endosomes ferry movement proteins to plasmodesmata, and how other SYTs may cooperate in this process. This knowledge of SYT action in plant cells will be connected to the regulation of development through promoter::GUS fusion studies to define their spatial and temporal expression, and analysis of transgenic lines in which the expression of each is inhibited by RNAi or T-DNA insertions.