MPK6 Contributes to Non-Host Resistance toMagnaporthe oryzaeinArabidopsis thaliana

Abstract

The rate of entry of Magnaporthe oryzae into pen2 mpk6 plants was higher than that into pen2 plants. The infection hyphae in the pen2 mpk6 plants were longer than those in the pen2 plants. The proportion of branched hyphae development in the pen2 mpk6 plants was higher than that in the pen2 plants. These results suggest that MPK6 functions in both penetration and post-penetration resistance to M. oryzae in Arabidopsis thaliana.Key words: non-host resistance; penetration; post-penetration; Magnaporthe oryzae Rice blast, caused by Magnaporthe oryzae, is a devastating disease of rice. The mechanisms of rice resistance to blast have been studied extensively, and the rice-M. oryzae pathosystem has become a model in plant-microbe interaction studies, 1,2) but the mechanisms of non-host resistance (NHR) to rice blast in other plants remain poorly understood.Arabidopsis mutants with altered non-host interactions following Blumeria graminis hordei (Bgh) infection were described recently, and three genes were identified: PENETRATION 1 (PEN1), PEN2, and PEN3.3-6) PEN1 encodes a plasma membrane-anchored syntaxin with a soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) domain. 3)PEN2 encodes an atypical myrosinase involved in glucosinolate metabolism in defense responses. 4,7,8) PEN3 encodes a pleiotropic drug resistance (PDR) ATP-binding cassette (ABC) transporter. 5,6) Collectively, these studies demonstrate that Arabidopsis NHR to nonadapted biotrophic powdery mildews has two successive multicomponent defense layers: penetration and postpenetration resistance. We have found that PEN2, PMR5, AGB1, and MLO2 are involved in both penetration and post-penetration resistance to M. oryzae in A. thaliana. 9-11)Plants have evolved effective basal defense systems to detect and limit the growth of pathogens. Pathogens can be recognized by the host via the perception of conserved microbial structures called pathogen-associated molecular patterns (PAMPs). PAMPs are recognized by transmembrane pattern recognition receptors (PRRs) that bind specific PAMPs and initiate intracellular immune responses.12) These PAMP-triggered immunity (PTI) responses include the generation of reactive oxygen species (ROS) and protein phosphorylation with associated gene regulation, which ultimately restricts the growth of the pathogens. 13)Mitogen-activated protein (MAP) kinase cascades play important roles in plant immunity. A MAP kinase cascade consists of a MAP kinase kinase kinase (MAPKKK), a MAP kinase kinase (MKK), and a MAP kinase (MPK).14) Signals from upstream receptors are transduced and amplified through the MAP kinase cascade. The best-characterized MPKs are MPK3, MPK4, and MPK6, each of which is activated by a diversity of stimuli, including abiotic stresses, pathogens, and oxidative stress in A. thaliana. While MPK4 negatively regulates biotic stress signaling, 15) MPK3 and MPK6 act as positive mediators of defense responses. 16)However, it remains to be clarified whether MPK4 and MPK3/MPK6 are involved in NHR to M...

GmMKK4‐activated GmMPK6 stimulates GmERF113 to trigger resistance to Phytophthora sojae in soybean

“…In this study, we found that GmMPK6 overexpression in soybean enhanced resistance to P. sojae, while silencing of GmMPK6 resulted in the opposite phenotype, implicating its positive role in soybean defense against P. sojae (Figure 2). This supports the previous reports that MPK6 plays a positive role in disease resistance to B. cinerea, Magnaporthe oryzae, Peronospora parasitica and P. syringae in Arabidopsis (Galletti et al, 2011;Han et al, 2019;Menke et al, 2004;Okawa & Ishikawa, 2013;Rasmussen et al, 2012). In N. benthamiana, Arabidopsis or tomato, infection of P. sojae and P. infestans can activate MAPK signaling pathways (Cheng et al, 2012;Du et al, 2021;King et al, 2014;Zheng et al, 2014), suggesting that the MKK-MPK modules are signaling components immediately downstream of immune receptors and can be induced by phytophthora pathogens.…”

SOBIR1 contributes to non-host resistance to Magnaporthe oryzae in Arabidopsis

“…We have found that PEN2, powdery mildew resistance 5 (PMR5), Arabidopsis Gprotein beta subunit 1 (AGB1), and mildew locus O 2 (MLO2) are involved in both penetration resistance and post-penetration resistance to M. oryzae in Arabidopsis. [18][19][20][21][22][23] Recently, we have also shown that the RLK ERECTA is a positive regulator of NHR to M. oryzae in Arabidopsis. 24) In this study, we examined the function of BAK1 and SOBIR1 in NHR to M. oryzae in Arabidopsis.…”

ERECTA contributes to non-host resistance to Magnaporthe oryzae in Arabidopsis

“…We have found that PEN2, powdery mildew resistance 5 (PMR5), Arabidopsis G-protein beta subunit 1 (AGB1), and mildew locus O 2 (MLO2) are involved in both penetration resistance and post-penetration resistance to M. oryzae in Arabidopsis. [11][12][13][14][15][16] We have also found that penetration resistance to M. oryzae in Col-0 was stronger than that of Ler in Arabidopsis. To examine the genetic basis underlying natural variation in the responses, we used a set of recombinant inbred lines derived from a Col × Ler cross and identified three quantitative trait loci (QTL) that govern the expression of NHR in Arabidopsis against M. oryzae.…”

“…11,13) Fungal inoculation and quantification of cell entry and fungal growth were conducted as previously described. [11][12][13][14][15][16] Data were compared using Tukey's highly significant difference (HSD) tests. Calculations were performed on three data-sets (n = 3), and p < 0.05 indicated statistically significant effects.…”