The Role of MPK6 as Mediator of Ethylene/Jasmonic Acid Signaling in Serendipita indica-Colonized Arabidopsis Roots

Abstract

Serendipita indica is an axenically cultivable fungus, which colonizes a broad range of plant species including the model plant Arabidopsis thaliana. Root colonization by this endophyte leads to enhanced plant fitness and performance and promotes resistance against different biotic and abiotic stresses. The involvement of MPK6 in this mutualistic interaction had been previously shown with an mpk6 A. thaliana mutant, which failed to respond to S. indica colonization. Here, we demonstrate that mpk6 roots are significantly less colonized by S. indica compared to wild-type roots and the foliar application of plant hormones, ethylene, or jasmonic acid, restores the colonization rate at least to the wild-type level. Further, hormone-treated mpk6 plants show typical S. indica-induced growth promotion effects. Moreover, expression levels of several genes related to plant defense and hormone signaling are significantly changed at different colonization phases. Our results demonstrate that the successful root colonization by S. indica depends on efficient suppression of plant immune responses. In A. thaliana, this process relies on intact hormone signaling in which MPK6 seems to play a pivotal role.

Inoculation With Piriformospora indica Is More Efficient in Wild-Type Rice Than in Transgenic Rice Over-Expressing the Vacuolar H+-PPase

“…But, this biotrophic phase is followed by a cell death-associated colonization phase, revealed to occur through induction of endoplasmic reticulum (ER) stress and suppression of unfolded protein response, resulting in ER swelling and activation of a γVPE/caspase 1–like-mediated cell death program, preceded by vacuolar collapse (Schäfer and Kogel, 2009; Qiang et al, 2012). Colonization with P. indica was also shown to reduce the availability of free sugars and amino acids to the root tip, to change host hormone homeostasis and to be dependent on efficient suppression of plant immune responses (Schäfer et al, 2009; Daneshkhah et al, 2018).…”

Epiphytic fungi induced pathogen resistance of invasive plant Ipomoea cairica against Colletotrichum gloeosporioides

“…Symbiosis between plants and microbes is a very common ecological relationship. Host plants obtain diverse benefits from the symbiosis involving the improvement of nutrition availability (Bertolazi et al, 2019), yields (Xia et al, 2016) and tolerance against abiotic as well as biotic stresses (Daneshkhah, Grundler & Wieczorek, 2018;Song et al, 2015). In this study, the occurrence rates of F. oxysporum and F. fujikuroi on leaf surface of I. cairica reached up to 100% regardless of habitat.…”

Piriformospora indica Primes Onion Response against Stemphylium Leaf Blight Disease

“…Similar to what we observed in S. vesicarium -infected onions, in a precedent study [ 44 ] we had shown that P. indica was responsible for an enhanced expression of Solanum lycopersicum chitinases, in the late stages of A. solani infection. Daneshkhah et al [ 110 ] also confirmed that P. indica -mediated upregulation of PR chitinases could hardly be noticed in A. thaliana roots in the early stages of infection, during the biotrophic colonisation phase, and was expressed later in time, at the cell death-associated stage. As suggested by Van Wees et al [ 67 ] chitinase regulation is primarily driven by ET/JA signalling pathway.…”

“…Basic and acidic chitinases belong to the glycosyl hydrolase family and are involved in plant disease resistance mechanisms [ 108 ]. Due to their role in fungal cell wall degradation, they are included among the pathogenesis-related (PR) proteins and are significantly induced in response to necrotrophic fungal infections [ 109 , 110 ]. Similar to what we observed in S. vesicarium -infected onions, in a precedent study [ 44 ] we had shown that P. indica was responsible for an enhanced expression of Solanum lycopersicum chitinases, in the late stages of A. solani infection.…”