Biology subjects

Munoz Hoyos, L.

Publications and source records attributed to Munoz Hoyos, L..

3 recordsLinked to original sources

bioRxiv2023

Network analyses reveal D clade ethylene response factors as major regulators of jasmonic acid-mediated resistance to early blight disease complex in tomato

Resistance mechanisms to early blight disease complex (EBDC) in tomato remain obscure given its polygenic and quantitative nature. We investigated the early defense responses of Heinz 1706 tomato to EBDC using RNA-seq. We observed distinct transcriptional reprofiling upon exposure to two EBDC isolates and the PAMP chitin. Avirulent isolate CS046 (Alternaria alternata) elicited a vigorous defense response in the host, whilst the virulent isolate 1117-1 (Alternaria sect. Porri) showed subdued gene expression, suggesting a suppression of defense responses during compatible pathogenesis. We emphasize the specific roles of ETHYLENE RESPONSE FACTORs (ERFs) in defense against EBDC, with a particular focus on the D clade ERFs. Co-expression network analysis revealed the principal genes in early defense responses to EBDC are secondary metabolite biosynthesis genes, transcription factors, and hormone response genes. We constructed a gene regulatory network and predicted novel hub genes as putative global regulators of the defense response, including the D clade ERFs, WRKY, and NAC transcription factors. Our work highlights the failure of virulent EBDC pathogenesis to elicit hormone responses that suppress cell death. Additionally, we found a selective induction for specific ERFs that strongly influence the topology of the EBDC defense transcriptional network.

plant biology↗

bioRxiv2023

Untargeted metabolomics reveals PTI-associated metabolites in cultivated tomato

Plants employ a multi-layered innate immune system to detect and fend off invading fungal pathogens. In one such layer, recognition of Pathogen- or Microbe-Associated Molecular Patterns or elicitors, triggers a signaling cascade that leads to defence against the pathogen and ultimately Pattern-Triggered Immunity (PTI). Secondary Metabolites (SMs) are expected to play an important role in this kind of resistance, because they are potentially mycotoxic compounds. Tomato plants inoculated with Alternaria solani show clear symptoms of infection 5 days after inoculation. Whereas plants inoculated with Alternaria alternata remain symptomless. We hypothesized that pattern-triggered induction of resistance-related metabolites in Solanum lycopersicum contribute to the resistance against A. alternata, yet such SMs are suppressed in a compatible interaction. We compared the metabolomic profile (metabolome) of S. lycopersicum at two time points (3 and 24 hours) after treatments with A. alternata, A. solani and the fungal elicitor chitin and identified SMs that are involved in the early defence response of tomato plants. Our study revealed differential metabolome fingerprints and shows that the molecular composition of A. alternata and chitin-induced indeed show larger overlap with each other than with the A. solani-induced metabolome. We identify 65 candidate metabolites possibly associated with pattern-triggered resistance in tomato plants, including the alkaloid, trigonelline, for which we can confirm that it inhibits fungal growth in vitro when supplied at physiological concentrations. Our findings show that a true, pattern-triggered, chemical defence is mounted against A. alternata and that it contains mycotoxin compounds previously unidentified in tomato, that could be interesting for future crop protection strategies.

plant biology↗

bioRxiv2022

Small-spored Alternaria spp. (section Alternaria) are common on wild tomato species

The wild relatives of modern tomato crops are native to South America. These plants occur in habitats as different as the Andes and the Atacama Desert and are to some degree all susceptible to fungal pathogens of the genus Alternaria. Alternaria is a large genus. On tomato, several species cause early blight, leaf spot, and other diseases. We collected Alternaria-like infection lesions from the leaves of eight wild tomato species from Chile and Peru. Using molecular barcoding markers, we characterized the pathogens. The infection lesions were caused predominantly by small-spored species of Alternaria of the section Alternaria, like A. alternata, but also by Stemphylium spp., Alternaria spp. from the section Ulocladioides, and other related species. Morphological observations and an infection assay confirmed this. Comparative genetic diversity analyses show a larger diversity in this wild system than in studies of cultivated Solanum species. As A. alternata has been reported to be an increasing problem on cultivated tomato, investigating the evolutionary potential of this pathogen is not only interesting to scientists studying wild plant-pathosystems. It could also inform crop protection and breeding programs to be aware of potential epidemics caused by species still confined to South America.

microbiology↗