Enhanced resistance in Theobroma cacao against oomycete and fungal pathogens by secretion of phosphatidylinositol‐3‐phosphate‐binding proteins |
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Authors: | Emily E. Helliwell Julio Vega‐Arreguín Zi Shi Bryan Bailey Shunyuan Xiao Siela N. Maximova Brett M. Tyler Mark J. Guiltinan |
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Affiliation: | 1. Department of Plant Science and Huck Institute of Life Sciences, The Pennsylvania State University, University Park, PA, USA;2. Center for Genome Research and Biocomputing, and Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR, USA;3. Virginia Bioinformatics Institute and Department of Plant Pathology, Physiology and Weed Science, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA;4. United States Department of Agriculture, Agricultural Research Service, Beltsville, MD, USA;5. Institute for Bioscience and Biotechnology Research & Department of Plant Science and Landscape Architecture, University of Maryland, College Park, MD, USA |
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Abstract: | The internalization of some oomycete and fungal pathogen effectors into host plant cells has been reported to be blocked by proteins that bind to the effectors' cell entry receptor, phosphatidylinositol‐3‐phosphate (PI3P). This finding suggested a novel strategy for disease control by engineering plants to secrete PI3P‐binding proteins. In this study, we tested this strategy using the chocolate tree Theobroma cacao. Transient expression and secretion of four different PI3P‐binding proteins in detached leaves of T. cacao greatly reduced infection by two oomycete pathogens, Phytophthora tropicalis and Phytophthora palmivora, which cause black pod disease. Lesion size and pathogen growth were reduced by up to 85%. Resistance was not conferred by proteins lacking a secretory leader, by proteins with mutations in their PI3P‐binding site, or by a secreted PI4P‐binding protein. Stably transformed, transgenic T. cacao plants expressing two different PI3P‐binding proteins showed substantially enhanced resistance to both P. tropicalis and P. palmivora, as well as to the fungal pathogen Colletotrichum theobromicola. These results demonstrate that secretion of PI3P‐binding proteins is an effective way to increase disease resistance in T. cacao, and potentially in other plants, against a broad spectrum of pathogens. |
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Keywords: |
Theobroma cacao
disease resistance phosphatidylinositol‐3‐phosphate‐binding protein effectors oomycetes fungi |
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