Transcriptional regulation of ethylene and jasmonate mediated defense response in apple (Malus domestica) root during Pythium ultimum infection

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.

Transcriptome changes specifically associated with apple (Malus domestica) root defense response during Pythium ultimum infection

“…ET/JA modulated defense responses during interaction between apple roots and P. ultimum were also studied by a recent candidate gene based approach [23]. Our data demonstrated that many DEGs associated with ET/JA biosynthesis and signal transduction were activated during the interaction between apple roots and P. ultimum.…”

“…The investigation of the molecular interaction between plant root and soilborne pathogens has lagged considerably behind foliar pathosystems. The molecular defense response in apple roots in response to the infection by ARD pathogens has rarely been explored [23]. A transcriptomic approach can offer the genome-wide view of the molecular regulation networks underlying the defense responses in apple root tissue towards soilborne ARD pathogens.…”

Apple Replant Disease: Causes and Mitigation Strategies

“…94 hormone metabolism (Shin et al, 2014(Shin et al, , 2016Zhu et al, 2014). Comparative transcriptomic studies of roots of the sensitive rootstock M26 grown either in ARD or gamma irradiated ARD soils revealed several differences in the expression of genes involved in stress responses (Weiß et al, 2017a, b).…”

Transcript Profiles of Auxin Efflux Carrier and IAA-Amido Synthetase Genes Suggest the Role of Auxin on Apple (<i>Malus</i> × <i>domestica</i>) Fruit Maturation Patterns

“…The sequences of the amplified regions seem to be identical between these two cultivars using qRT-PCR method. The internal reference of an apple MdActin (MDP0000752428) has been used in several previous studies and its consistency among various tissue types and treatments has been tested in several studies [54]- [56]. Additionally, use of "adaptive calibrator" for calculating the relative expression values enhances the comparability of the relative gene expression levels between two cultivars.…”