Project description:Colletotrichum coccodes secretes ammonium during germination and colonization of host tissue as a mechanism for dual activation of fungal pathogenicity factors and plant cell death via activation of host NADPH oxidase. Ammonium accumulation during colonization of tomato fruits by C. coccodes induced host nucleus integrity changes and program cell death (PCD). Transcriptome analysis at the leading edge of colonized tissue and ammonium treated tomato fruits revealed 82 and 237 common up-regulated and common down-regulated genes, respectively. The common-up-regulated genes showed over representation of pathogen related (PR) proteins, salicylic acid (SA) dependent and systemic acquired resistance (SAR) related genes and genes related to biotic stress. The down regulated genes showed over representation of Jasmonic acid (JA) dependent genes. Consistent with this observation the direct application of SA enhanced C. coccodes colonization, whereas the application of JA delayed colonization. Candidate genes were selected for QRT-PCR analysis of transcripts in normal and transgenic RBOH antisense plants and showed dependence on RBOH regulation. In all, the results suggest that ammonia accumulation during C. coccodes colonization activates SA and suppress JA pathways through activation of RBOH. The effects of ammonium on the expression of the selected up-and down regulated genes were examined in fruit of different maturation stages. Red, susceptible and green resistant, tomato fruit displayed similar behavior, suggesting that resistance of green fruits to C. coccodes colonization is not modulated by the JA and SA pathways but depends on other factors
Project description:Colletotrichum coccodes secretes ammonium during germination and colonization of host tissue as a mechanism for dual activation of fungal pathogenicity factors and plant cell death via activation of host NADPH oxidase. Ammonium accumulation during colonization of tomato fruits by C. coccodes induced host nucleus integrity changes and program cell death (PCD). Transcriptome analysis at the leading edge of colonized tissue and ammonium treated tomato fruits revealed 82 and 237 common up-regulated and common down-regulated genes, respectively. The common-up-regulated genes showed over representation of pathogen related (PR) proteins, salicylic acid (SA) dependent and systemic acquired resistance (SAR) related genes and genes related to biotic stress. The down regulated genes showed over representation of Jasmonic acid (JA) dependent genes. Consistent with this observation the direct application of SA enhanced C. coccodes colonization, whereas the application of JA delayed colonization. Candidate genes were selected for QRT-PCR analysis of transcripts in normal and transgenic RBOH antisense plants and showed dependence on RBOH regulation. In all, the results suggest that ammonia accumulation during C. coccodes colonization activates SA and suppress JA pathways through activation of RBOH. The effects of ammonium on the expression of the selected up-and down regulated genes were examined in fruit of different maturation stages. Red, susceptible and green resistant, tomato fruit displayed similar behavior, suggesting that resistance of green fruits to C. coccodes colonization is not modulated by the JA and SA pathways but depends on other factors Ten micrograms of total RNA was processed for the microarray hybridizations using the Affymetrix GeneChip one-cycle target-labeling kit (Affymetrix). The four treatments were: C. coccodes "mat inoculation" compared to a wound control (24 hours after the tomato fruit peel was removed). 5 mM Ammonium treatment in PBS compared to PBS treatments as a control for ammonium treatment, the treatments applied every four hours. Each treatment had a duplicate. The biotinylated complementary RNA was fragmented and hybridized to the GeneChip Tomato Genome Array (10,038 tomato probe sets for more than 9,200 tomato genes). The arrays were washed, stained, and scanned at the biological services (Weizmann institute of science, Rehovot, Israel). CEL files for the Affymetrix microarray data arising from the microarray experiments were analyzed utilizing the Partek genomics software (Downey, 2006).
Project description:Species from the genus Colletotrichum are the causal agents of anthracnose which contribute to significant losses to the production of commercially grown crops. The genomes of Colletotrichum orbiculare, which infects cucurbits and Nicotiana benthamiana, as well as Colletotrichum gloeosporioides, which infects a wide range of fruits and vegetables, were sequenced. A custom microarray was designed for Colletotrichum orbiculare and used to assess gene expression during infection of Nicotiana benthamiana. Gene expression of Colletotrichum orbiculare growing on its host Nicotiana benthamiana was assessed at 24 hours post inoculation, 3 days post inoculation and 7 days post inoculation. Mycelia growing in vitro and ungerminated conidia were used as controls. Three replicates were performed for each time point.