Project description:In this experiment we measured the transcriptional response of ten tomato cultivars when infected by the plant-parasitic nematode M. incognita. The ten cultivars showed differential levels of susceptibility to M. incognita infection. Ten-days old plants were exposed to nematodes and harvested 1, 2, 3, 4, 7, or 10 days post infection. Galls or representative uninfected tissues were harvested and used for RNA sequencing. The data was used to investigate the link between susceptibility to M. incognita infection and gene expression in tomato.
Project description:Trichoderma harzianum T34 is a fungal strain able to promote the plant growth and to increase plant defense responses. Trichoderma harzianum transformants expressing the amdS gene, encoding an acetamidase, of Aspergillus nidulans produce a higher plant development than the wild type T34. We used microarrays to analyze the physiological and biochemical changes in tomato plants produced as consequence of interaction with Trichoderma harzianum T34 and amdS transformants
Project description:Plant pathogens with a broad host range are able to infect plant lineages that diverged over 100 million years ago. They exert similar and recurring constraints on the evolution of unrelated plant populations. Plants generally respond with quantitative disease resistance (QDR), a form of immunity relying on complex genetic determinants. In most cases, the molecular determinants of QDR and how they evolve is unknown. Here we identify in Arabidopsis thaliana a gene mediating QDR against Sclerotinia sclerotiorum, agent of the white mold disease, and provide evidence of its convergent evolution in multiple plant species. Using genome wide association mapping in A. thaliana, we associated the gene encoding the POQR prolyl-oligopeptidase with QDR against S. sclerotiorum. Loss of this gene compromised QDR against S. sclerotiorum but not against a bacterial pathogen. Natural diversity analysis associated POQR sequence with QDR. Remarkably, the same amino acid changes occurred after independent duplications of POQR in ancestors of multiple plant species, including A. thaliana and tomato. Genome-scale expression analyses revealed that parallel divergence in gene expression upon S. sclerotiorum infection is a frequent pattern in genes, such as POQR, that duplicated both in A. thaliana and tomato. Our study identifies a previously uncharacterized gene mediating QDR against S. sclerotiorum. It shows that some QDR determinants are conserved in distantly related plants and have emerged through the repeated use of similar genetic polymorphisms at different evolutionary time scales.
Project description:Graft compatibility is the ability of two plants to form cohesive vascular connections. Tomato and pepper grafts are incompatible but the underlying causes of this phenomenon remain unknown. We utilzied a broad array of techniques to profile graft compatibility including viability, biophysical stability, and growth. Cell death in the junction was quantified using trypan blue and TUNNEL assays. Transcriptomic analysis of cell death in the junction was preformed using RNA-sequncing. Finally a meta-transcriptomic analysis was conducted with published datasets to further explore the genetic signature of graft incompatibility.We found that all varieties of pepper tested across two species were incompatible with tomato. Tomato and pepper graft incompatibility is characterized by stem instability, reduced growth, and persistent cell death in the graft junction. We showed that tomato and pepper heterografts have prolonger transcriptional activity, with defense processes highly enrched. We identfied a large subset of NLRs and genes involved in programmed cell death which were upregulated in incompatible tissue. We also identified a set of genes with orthologs in both tomato and pepper which are upregulated in incompatible grafts including biosythesis of steroidal glycoalkaloids. Finally we utilized various biological stressors to explore the genetic signature of grafting. We found a significant overlap in the genetic profile of grafting and plant parsitism. We also identified over 1000 genes uniquely upregulated in incompatible grafting including genes in involved in DNA-damage repair. Based on the broad upregulation of NLRs and genes involved with programmed cell death, prolonged cell death in the junction, and DNA damage, we have determined that tomato and pepper graft incompatibility is likely caused by a form of genetic incompatibility which triggers an autoimmune-like response.
Project description:Salt stress causes the quality change and significant yield loss of tomato. However, the resources of salt-resistant tomato were still deficient and the mechanisms of tomato resistance to salt stress were still unclear. In this study, the proteomic profiles of two salt-tolerant and salt-sensitive tomato cultivars were investigated to deciphered the salt-resistance mechanism of tomato and provide novel resources for tomato breeding. We found that there is an over-abundant proteins relevant to Nitrate and amino acids metabolisms in the Salt-tolerant cultivars. The significant increase in expression of proteins involved in Brassinolides and GABA biosynthesis were verified in salt-tolerant cultivars, strengthening the salt resistance of tomato. Meanwhile, salt-tolerant cultivars with higher abundance and activity of antioxidant-related proteins have more advantages in dealing with reactive oxygen species caused by salt stress. And the salt-tolerant cultivars had higher photosynthetic activity based on overexpression of proteins functioned in chloroplast, guaranteeing the sufficient nutrient for plant growth under salt stress. Furthermore, three key proteins were identified as important salt-resistant resources for breeding salt-tolerant cultivars, including Sterol side chain reductase, gamma aminobutyrate transaminase and Starch synthase. Our results provided series valuable strategies for salt-tolerant cultivars which can be used in future