Project description:Blue mold, caused by Penicillium expansum, is responsible for postharvest losses of apple fruit, and threatens human health through production of the potent mycotoxin patulin. No major gene(s) providing resistance have as yet been identified, but recent studies indicate a quantitative control of the disease. An AryANE chip covering 60K apple transcripts was used to identify possible candidate gene(s) that are differentially regulated between resistant and susceptible cultivars upon P. expansum infection. Induction of cell wall related gene (PGIP1), and three genes involved in the ‘down-stream’ flavonoid biosynthesis pathway (CHS, FLS and LDOX), shows the fundamental role of cell wall as an important barrier, and contents of polyphenolic compounds of fruits as a quantitative components in enhancing disease resistance to blue mold. Moreover, exogenous application of Jasmonic acid hormone enhanced the defense mechanism in fruits. This is the first report linking Jasmonic acid and activation of cell wall and flavonoid pathway genes in apple fruit resistance to blue mold. Results provide an initial categorization of genes that are potentially involved in the resistance mechanism, and should be useful for developing tools for gene marker-assisted breeding of apple cultivars with an improved resistance to blue mold. SUBMITTER_CITATION: Ahmadi-Afzadi, M., Orsel Baldwin, M., Pelletier, S., Cournol, M., Proux-Wéra, E., Nybom, H., Renou, J.-P. (2018). Genome-wide expression analysis suggests a role for jasmonates in the resistance to blue mold in apple. Plant Growth Regulation, 85 (3), 375-387. , DOI : 10.1007/s10725-018-0388-2
Project description:Using whole genome bisulfite sequencing to provide single-base resulution of DNA methylation status in apple fruits ( Malus x domestica Borkh. ) in four different stages.
Project description:Apple is one of the most important fruits that is propagated vegetatively, facilitating frequent transmission of viruses. The causative agent of the apple rubbery wood disease, apple rubbery wood virus 2 (ARWV2), can infect apple and pear. The branches of ARWV2-infected, symptomatic trees are flexible due to the decreased lignification of the xylem. In this research, we reanalysed our sRNA HTS datasets to survey the presence of ARWV2 in Hungary. Validation of HTS using RT-PCR revealed infection in several cultivars. The following RT-PCR-based survey revealed the infection of 15 trees, including pear and quince, without showing any rubbery wood symptoms. Analysis of the sRNA datasets allowed us to profile the sRNA pattern of ARWV2-infected and non-infected trees, and characterise the differential expression pattern of vsiRNAs and miRNAs targeting the lignin biosynthetic pathway. The results confirmed that neither the symptoms nor the gene-expression changes in the ARWV2-infected trees can be directly correlated with the presence of the virus, which can explain its frequent latent presence. Its variable concentration, sequence, and the mixed-infection status of the trees, make difficult its reliable diagnostics, which, although it would be highly needed, could be achieved as a result of further research.
Project description:The main objective of this analysis was to sequence the epigenome of the Apple (Malus domestica) doubled haploid 'Golden Delicious' tree. Our secondary objective was to identify differentially methylated regions between DNA purified from leaves and young fruits.
Project description:Gene expression associated with apple fruit ripening and postharvest treatments was studied to identify transcripts that are regulated by ethylene signaling.
Project description:A transcriptomic approach was implemented using two Penicillium species to identify genes related to fungal aggressiveness in apple fruit and loci contained in ungerminated conidia. Total RNA was isolated from ungerminated conidia and decayed apple fruit infected with P. expansum R19 (aggressive) or P. polonicum RS1 (weak). There were 2,442 differentially expressed genes (DEGs) between the R19 and RS1 in apple and comparisons within species between apple and conidia revealed 4,404 DEGs for R19, and 2935 for RS1, respectively. Gene ontology (GO) revealed differential regulation in fungal transport and metabolism genes expressed during decay, suggesting a flux in nutrient acquisition and detoxification strategies. In R19, the oxidoreductase GO category comprised 20% of all groups differentially expressed in decayed apple verses ungerminated conidia in addition to those involved in hydrogen peroxide metabolism. Ungerminated conidia from both species showed higher expression of genes encoding the glyoxylate shunt and beta-oxidation, specifying the earliest metabolic requirements for germination
Project description:The ripening of climacteric fruits, such as apple, is represented by a series of genetically programmed events orchestrated by the action of several hormones. In this work, we investigated the existence of a hormonal crosstalk between ethylene and auxin during the post-harvest ripening of three internationally known apple cultivars: ‘Golden Deli-cious’, ‘Granny Smith’ and ‘Fuji’. The normal climacteric ripening was impaired by the exogenous application of 1-methylcyclopropene (1-MCP) that effectively affected the production of ethylene and the physiological behaviour of specific ethylene-related qual-ity traits, such as fruit texture and the production of volatile organic compounds showed a de-novo accumulation of auxin following the application of 1-MCP. The RNA-Seq wide-transcriptome analysis evidenced as the competition at the level of the ethylene re-ceptors induced a cultivar-dependent transcription re-programming. The DEGs annota-tion carried out through the KEGG database identified as most genes were assigned to the plant hormone signaling transduction category, and specifically related to auxin and ethylene. The interplay between these two hormones was further assessed through a candidate gene analysis that highlighted a specific activation of GH3 and ILL genes, en-coding key steps in the process of the auxin homeostasis mechanism. Our results showed that a compromised ethylene metabolism at the onset of the climacteric ripening in apple can stimulate, in a cultivar-dependent fashion, an initial de-novo synthesis and de-conjugation of auxin as a tentative to restore a normal ripening progression.