Two Endopolygalacturonase Genes in Trichoderma virens: In Silico Characterization and Expression during Interaction with Plants

Abstract

The ability of Trichoderma spp. to antagonize most phytopathogenic fungi\ud and to interact with plants by inducing their resistance and promoting\ud their growth has been widely described. Endopolygalacturonases\ud (endoPGs) produced by Trichoderma spp. can assist root penetration and\ud play a pre-eliciting role in induced systemic resistance (ISR), a beneficial\ud effect detected in plants colonized by Trichoderma. In this study, two\ud endoPG genes (Tvpg1 and Tvpg2) have been identified and partially characterized\ud in a T. virens isolate, previously investigated for its antagonistic\ud ability in several biological systems. An extensive in silico analysis showed\ud relatively low sequence similarities (53%) between TvPG1 and TvPG2\ud proteins and underscored interesting phylogenetic relationships in the\ud comparison of endoPG genes among fungal genomes. The phylogeny of\ud endoPGs suggests a differentiation in action mechanisms associated with\ud biological functions as one cluster shows only genes from plant-interacting\ud organisms. A gene expression analysis demonstrated a different regulation\ud pattern for those genes. The Tvpg1 gene was induced both when the\ud fungus was grown in liquid cultures supplemented with pectin or plant\ud cell walls and when it was applied to tomato roots in a growth chamber.\ud Expression times were comparable in both systems. On the contrary, the\ud Tvpg2 gene displayed a constitutive expression in all conditions tested,\ud including controls. The molecular communication between tomato roots\ud and T. virens was investigated by checking the expression of a tomato PGIP\ud (Lepgip1) in roots colonized by fungal mycelium. The Lepgip1 transcript\ud was induced at times coincident with Tvpg1 expression, suggesting a correlation\ud between the two gene products. This paper reports the results of\ud first investigations of T. virens endoPG genes performed on a structural,\ud phylogenetic and functional level

Phosphorus availability drives mycorrhiza induced resistance in tomato

“…Thus, the expression analyses confirmed a primed response of mycorrhizal plants to the OG treatment under sufficient P (Figures 5A-D; Table S5). A similar primed response was found for the gene encoding a defense polygalacturonase inhibiting protein (LePGIP), also related to defense responses (Baroncelli et al, 2016) (Figure 5E).…”

Molecular interaction between plants and Trichoderma species against soil-borne plant pathogens

“…A study of T. harzianum-root interaction in Arabidopsis and tomato led to the discovery of the first DAMP, which corresponds to the oligogalactouronides produced by the enzymatic activity of CWDE endopolygalacturonase ThPG1 in T. harzianum, which was found to be capable of inducing systemic defense in the plants ( Moran-Diez et al, 2009). In a study conducted by Baroncelli et al (2016), the expression of two endopolygalcturonase genes (viz., TvPg1 and TvPg2) from T. virens I10 was examined during the interaction with tomato roots. The results revealed that, while interacting with, in particular, host roots or pectin, expression of TvPg1 was induced, whereas TvPg2 was later expressed constitutively.…”

Characterization of a novel thermophilic endopolygalacturonase produced by Bacillus licheniformis IEB-8

“…The 16S rRNA gene sequence of B. licheniformis IEB-8 was blasted in the NCBI nucleotide database. The 16S rRNA gene sequence of the first ten strains showed resemblance to the isolate used for the multiple sequence alignment (ClustalW; https://www.genome.jp/tools-bin/clustalw) and for the construction of the phylogenetic tree using Multiple Evolutionary Genetic Analysis (MEGA) (Version 6, https://www.megasoftware.net/download_form) (Baroncelli et al 2016;Khan and Latif 2016).…”