Poster: Plant Pathogen/Symbiont Interactions
Abs #
695: Inducible and developmentally regulated genes potentially involved in protecting Theobroma cacao leaves from disease
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Presenter: |
Bailey, Bryan A., baileyb@ba.ars.usda.gov | Authors | Bailey, Bryan A. (A) Antunez de Mayolo, Gabriela (B) Guiltinan, Mark (B) | | Affiliations: |
(A): Alternate Crops and Systems Laboratory, PSI/ARS/USDA, BARC-West, Beltsville, MD 20705
(B): Department of Horticulture, Pennsylvania State University, University Park, PA 16802
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The leaves of Theobroma cacao (cacao) are susceptible to disease caused by Crinipellis perniciosa (Witches’ broom) and Phytophthora spp. (Black pod) during their early stages of development, but cacao leaves become resistant to disease as they mature. We are studying the expression of several cacao genes during leaf development under conditions that induce plant defense. The genes being studied putatively code for a peroxidase, a chitinase, a caffeine synthase, a WRKY gene, a gene related to ORFX of tomato, and a Chlorophyll A/B binding protein. Inducers being studied include wounding by puncturing, the commercial products Bion (SA homologue) and Messenger (Harpin) reported to induce SAR and/or ISR, and the necrosis inducing fungal protein Nep1. Cacao leaves are being studied at four stages of development: 1) immature leaves less than 1 cm in length, 2) rapidly expanding immature leaves 4 to 10 cm in length (pigmented red and very flexible), 3) fully expanded immature leaves (green and very flexible), and 4) recently matured leaves (green and very rigid). Depending upon the gene being studied, the constitutive expression varies greatly between the different stages of development. The WRKY, ORFX, peroxidase, and chitinase genes are weakly inducible in mature cacao leaves. Based on the published data of others, developing cacao leaves may be highly inducible for some of the genes being studied. We continue to study, at different developmental stages, the inducible expression of genes believed to be involved in plant defense in cacao leaves.
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