Structural Diversity and Highly Specific Host-Pathogen Transcriptional Regulation of Defensin Genes Is Revealed in Tomato

Abstract

Defensins are small and rather ubiquitous cysteine-rich anti-microbial peptides. These proteins may act against pathogenic microorganisms either directly (by binding and disrupting membranes) or indirectly (as signaling molecules that participate in the organization of the cellular defense). Even though defensins are widespread across eukaryotes, still, extensive nucleotide and amino acid dissimilarities hamper the elucidation of their response to stimuli and mode of function. In the current study, we screened the Solanum lycopersicum genome for the identification of defensin genes, predicted the relating protein structures, and further studied their transcriptional responses to biotic (Verticillium dahliae, Meloidogyne javanica, Cucumber Mosaic Virus, and Potato Virus Y infections) and abiotic (cold stress) stimuli. Tomato defensin sequences were classified into two groups (C8 and C12). Our data indicate that the transcription of defensin coding genes primarily depends on the specific pathogen recognition patterns of V. dahliae and M. javanica. The immunodetection of plant defensin 1 protein was achieved only in the roots of plants inoculated with V. dahliae. In contrast, the almost null effects of viral infections and cold stress, and the failure to substantially induce the gene transcription suggest that these factors are probably not primarily targeted by the tomato defensin network.

Morphological Diversity, Genetic Characterization, and Phytochemical Assessment of the Cypriot Tomato Germplasm

“…From an alimentary supply standpoint, tomato fruits are a significant source of vitamins, fibers, sugars, and essential minerals for the human diet [ 4 ]. Moreover, besides its universal farming and financial standing as a crop, tomato is also a pre-eminent model system for fundamental and applied plant genetic studies focusing on the ripening process [ 5 ], secondary metabolism pathways [ 6 ] and immunity against biotic stress [ 7 , 8 ].…”

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

“…H1 [85], SlERF . F5 (Solyc10g009110) [86], SlERF014 (Solyc11g012980) [87], SlWRKY39 (Solyc03g116890) [88], defensin SlDEF9 (Solyc07g007755) [89], and zinc-finger protein SlZF-62 (Solyc06g075780), whose homolog in A. thaliana is upregulated in response to chitin [90], among others. 14 genes were predicted to be hub genes for the yellow module GRN ( supp.…”

“…The turquoise module is the chitin-associated co-expression module, and therefore these genes contribute to generalized defense responses. Notable turquoise module GRN hub genes with known defense roles include three ERFs, SlERF.H1 [85], SlERF.F5 (Solyc10g009110) [86], SlERF014 (Solyc11g012980) [87], SlWRKY39 (Solyc03g116890) [88], defensin SlDEF9 (Solyc07g007755) [89], and zinc-finger protein SlZF-62 (Solyc06g075780), whose homolog in A. thaliana is upregulated in response to chitin [90], among others. 14 genes were predicted to be hub genes for the yellow module GRN (supp.…”