Hunting modulators of plant defence: the grapevine trunk disease fungus Eutypa lata secretes an amplifier for plant basal immunity

Abstract

Grapevine trunk diseases (GTDs) are progressively affecting vineyard longevity and productivity worldwide. To be able to understand and combat these diseases, we need a different concept of the signals exchanged between the grapevine and fungi than the well-studied pathogen-associated molecular pattern and effector concepts. We screened extracts from fungi associated with GTDs for their association with basal defence responses in suspension cells of grapevine. By activity-guided fractionation of the two selected extracts, O-methylmellein was identified as a candidate modulator of grapevine immunity. O-Methylmellein could not induce immune responses by itself (i.e. does not act as an elicitor), but could amplify some of the defence responses triggered by the bacterial elicitor flg22, such as the induction level of defence genes and actin remodelling. These findings show that Eutypa lata, exemplarily selected as an endophytic fungus linked with GTDs, can secrete compounds that act as amplifiers of basal immunity. Thus, in addition to elicitors that can trigger basal immunity, and effectors that down-modulate antibacterial basal immunity, once it had been activated, E. lata seems to secrete a third type of chemical signal that amplifies basal immunity and may play a role in the context of consortia of mutually competing microorganisms.

Transcriptome Analysis and Cell Morphology of Vitis rupestris Cells to Botryosphaeria Dieback Pathogen Diplodia seriata

“…Firstly, the MTs’ performance against 0.1% ( v / v ) culture filtrates of D. seriata 98.1 at 3 dpi was examined, where the MTs were depolymerized with a skewness value of 1.03 (skewness value is 1.29 in control cells) ( Figure 4 A). As the cytoskeleton participates in early signaling transduction in plant defense as a sensor and integrator [ 13 ], the remodeling of microtubules at earlier time points was interesting to observe. A compromised filtrate concentration has to be carefully considered with the incubation time (where MTs rearrangement is different between a prompt response with a higher concentration vs. a long-term response with a mild concentration).…”

“…Several toxic factors were found to be synthesized by the species of Botryosphaeriaceae, including mellein, cis, trans-4-hydroxymellein, 4,7-dihydroxymellein, naphthalene enone-related compounds and lipophilic low-molecular weight phytotoxins (exopolysaccharides, peptides or proteins) [ 7 ]. It has been demonstrated that extracellular compounds produced by Botryosphaeriaceae species induced defense gene expression in grapevine cells [ 7 , 12 , 13 ]. Moreover, extracellular proteins produced by N. parvum induced more intense early defense responses in Vitis rupestris cells than those produced by Diplodia seriata [ 4 ].…”

Ancestral chemotypes of cultivated grapevine with resistance to Botryosphaeriaceae‐related dieback allocate metabolism towards bioactive stilbenes

“…Our working model predicts that GTD-related fungi secrete compounds that can modify grapevine immunity. The recent finding that the GTD fungus Eutypa lata secretes O-methylmellein that can amplify defence responses triggered by the bacterial PAMP flg22 (Guan et al, 2020) suggests that there is still much to be discovered in plant-fungal communication. Ó 2020 The Authors New Phytologist Ó 2020 New Phytologist Trust www.newphytologist.com taught IK the infection assay.…”

Hunting the plant surrender signal activating apoplexy in grapevines after Neofusicoccum parvum infection

“…The integrity of cortical microtubules was estimated according to Schwarzerová, et al (2002). We collected four intensity profiles along the long axis of the cell in equal spacing over the cross axis and using a line width of 25 pixels according to modifications described in Guan et al (2020). For both, microtubules, and actin filaments, twenty-five individual cells were scored for each treatment representing 4 independent biological replicates.…”