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Resistance of Malus domestica Fruit to Botrytis cinerea Depends on Endogenous Ethylene Biosynthesis

November 2011 , Volume 101 , Number  11
Pages  1,311 - 1,321

Aya Akagi, Abhaya M. Dandekar, and Henrik U. Stotz

First and third authors: Department of Horticulture, 4017 Agriculture & Life Sciences Bldg., Oregon State University, Corvallis 97331; and second author: Department of Plant Sciences, 152 Robbins Hall, University of California, Davis 95616.

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Accepted for publication 16 June 2011.

The plant hormone ethylene regulates fruit ripening, other developmental processes, and a subset of defense responses. Here, we show that 1-aminocyclopropane-1-carboxylic acid synthase (ACS)-silenced apple (Malus domestica) fruit that express a sense construct of ACS were more susceptible to Botrytis cinerea than untransformed apple, demonstrating that ethylene strengthens fruit resistance to B. cinerea infection. Because ethylene response factors (ERFs) are known to contribute to resistance against B. cinerea via the ethylene-signaling pathway, we cloned four ERF cDNAs from fruit of M. domestica: MdERF3, -4, -5, and -6. Expression of all four MdERF mRNAs was ethylene dependent and induced by wounding or by B. cinerea infection. B. cinerea infection suppressed rapid induction of wound-related MdERF expression. MdERF3 was the only mRNA induced by wounding and B. cinerea infection in ACS-suppressed apple fruit, although its induction was reduced compared with wild-type apple. Promoter regions of all four MdERF genes were cloned and putative cis-elements were identified in each promoter. Transient expression of MdERF3 in tobacco increased expression of the GCC-box containing gene chitinase 48.

© 2011 The American Phytopathological Society