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Article|29 Oct 2014|OPEN
Transcriptional regulation of ethylene and jasmonate mediated defense response in apple (Malus domestica) root during Pythium ultimum infection
Sungbong Shin1 , Jingyi Lv2 , Gennaro Fazio3 , Mark Mazzola1 and Yanmin Zhu,1 ,
1United States Department of Agriculture, Agricultural Research Service, Tree Fruit Research Laboratory, Wenatchee, WA 98801, USA
2College of Horticulture, Northwest A&F University, Yangling, shanxi 712100, China
3United States Department of Agriculture, Agricultural Research Service, Plant Genetic Resources Unit, Geneva, NY 14456, USA
*Corresponding author. E-mail: yanmin.zhu@ars.usda.gov

Horticulture Research 1,
Article number: 53 (2014)
doi: https://doi.org/10.1038/hortres.2014.53
Views: 722

Received: 06 Aug 2014
Revised: 12 Sep 2014
Accepted: 17 Sep 2014
Published online: 29 Oct 2014

Abstract

Apple replant disease (ARD) is a significant economic restraint to the successful re-establishment of new apple orchards on sites previously planted to the same crop. Pythium ultimum, an oomycete, is a significant component of the ARD pathogen complex. Although ethylene (ET)- and jasmonic acid (JA)-mediated defense responses are intensively studied in the foliar pathosystem, the transferability of this knowledge to the interaction between a perennial root system and soilborne pathogens is unknown. The aim of this study was to test the hypothesis that the ET/JA-mediated defense response is conserved in roots of tree crops in response to infection by P. ultimum. Apple genes with the annotated function of ET/JA biosynthesis, MdERF (ethylene response factor) for signaling transduction and a gene encoding a pathogenesis-related (PR) protein (β-chitinase, the target of ERF) were identified from the apple genome sequences. The transcriptional profiles of these genes during P. ultimum infection and after exogenous ET and/or JA treatment were characterized using qRT-PCR. Several genes showed a 10- to 60-fold upregulation in apple root tissue 24-48 h post inoculation (hpi). Exogenous ET and JA treatment exhibited either a positive or negative influence on expression of ET or JA biosynthesis genes, depending upon gene isoforms and the tissue types, while the expression of MdERF and the PR protein encoding gene was upregulated by both ET and JA treatment. Our data are consistent with the hypothesis that ET/JA-mediated defense pathways are functional in the root system of perennial tree species defending soilborne pathogens.