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:PHYTOCHROME-INTERACTING FACTORs (PIFs) regulate growth-related gene expression in response to environmental conditions. Among their diverse functions in regulating signal responses, PIFs play an important role in thermomorphogenesis (the response to increased ambient temperature) and in the shade-avoidance response. While numerous studies have examined the varied roles of PIFs in Arabidopsis (Arabidopsis Thaliana), their roles in crop plants remain poorly investigated. This study delves into the conservation of PIFs activity among species by examining their functions in tomato (Solanum lycopersicum) and comparing them to known PIF functions in Arabidopsis using single and higher-order mutants of tomato PIF genes (SlPIFs). We demonstrate that, in contrast to Arabidopsis, PIFs are not required for thermomorphogenesis-induced stem elongation in tomato. In addition, whereas Arabidopsis PIF8 has a minor effect on plant growth, tomato SlPIF8a plays a key role in the low red/far-red (R/FR) response. In contrast, SlPIF4 and SlPIF7s play minor roles in this process. We also investigated the tissue-specific low R/FR response in tomato seedlings and demonstrate that the aboveground organs exhibit a conserved response to low R/FR, which is regulated by SlPIFs. Our findings provide insights into PIF-mediated responses in crop plants, which may guide future breeding strategies to enhance yield under high planting densities.
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.