Root‐knot nematodes induce pattern‐triggered immunity in Arabidopsis thaliana roots

Abstract

SummaryRoot-knot nematodes (RKNs; Meloidogyne spp.) are plant parasites with a broad host range causing great losses worldwide. To parasitize their hosts, RKNs establish feeding sites in roots known as giant cells. The majority of work studying plant-RKN interactions in susceptible hosts addresses establishment of the giant cells and there is limited information on the early defense responses.Here we characterized early defense or pattern-triggered immunity (PTI) against RKNs in Arabidopsis thaliana. To address PTI, we evaluated known canonical PTI signaling mutants with RKNs and investigated the expression of PTI marker genes after RKN infection using both quantitative PCR and b-glucuronidase reporter transgenic lines.We showed that PTI-compromised plants have enhanced susceptibility to RKNs, including the bak1-5 mutant. BAK1 is a common partner of distinct receptors of microbe-and damageassociated molecular patterns. Furthermore, our data indicated that nematode recognition leading to PTI responses involves camalexin and glucosinolate biosynthesis. While the RKNinduced glucosinolate biosynthetic pathway was BAK1-dependent, the camalexin biosynthetic pathway was only partially dependent on BAK1.Combined, our results indicate the presence of BAK1-dependent and -independent PTI against RKNs in A. thaliana, suggesting the existence of diverse nematode recognition mechanisms.

RNA‐Seq identification of candidate defense genes targeted by endophytic Bacillus cereus‐mediated induced systemic resistance against Meloidogyne incognita in tomato

“…Mi‐CRT and Misp12 from M. incognita and MjTTL5 from M. javanica are effectors in PPNs that suppress PTI . The study of plant defenses against nematodes has concentrated on disease resistance proteins and effector‐triggered immunity (ETI) . In direct and indirect host recognition of pathogen effectors, local and systemic changes in gene expression are mediated largely by the MYB and WRKY transcription factors families .…”

“…In direct and indirect host recognition of pathogen effectors, local and systemic changes in gene expression are mediated largely by the MYB and WRKY transcription factors families . It has been reported that AtWRKY23 is expressed during the early stages of feeding site establishment of PPNs, and WRKY11 and WRKY17 are positive regulators of RKN defense . Overexpression of WRKY41 showed enhanced resistance to pathogens in A. thaliana , inducing expression of the PR5 gene, but suppression of the MeJA‐induced PDF1.2 gene .…”

“…Meanwhile, the level of induced resistance was shown to be further enhanced when both ISR and SAR are activated simultaneously in Arabidopsis . Plant defense responses include resistance against infection by pathogens and parasites, which is commonly recognized as a pathogen‐associated molecular pattern (PAMP), leading to pattern‐triggered immunity (PTI) . Subsequently, many events are induced: activation of the mitogen‐activated protein kinase (MAPK) signaling cascade, callose deposition, bursts of reactive oxygen species, and rapid changes in gene expression .…”

Gene expression profiling describes the genetic regulation of Meloidogyne arenaria resistance in Arachis hypogaea and reveals a candidate gene for resistance

“…Camalexin is a well-known antimicrobial compound. An Arabidopsis mutant line with impaired camalexin synthesis supported significantly more gall production than the wild type 56 . In the cell signaling category, phosphoinositide synthesis and degradation were modulated similarly between Gregory and Tifguard upon nematode invasion.…”

Plant elicitor peptides promote plant defences against nematodes in soybean

“…Together, these data suggest that receptor‐mediated perception of Peps triggers RBOHD‐dependent ROS production via a BAK1/BIK1 phosphorylation cascade. Previous studies have shown that PTI against RKNs in Arabidopsis is compromised in mutants with impairments in BAK1 , BIK1 or NADPH oxidase genes ( RBOHD/F ) (Teixeira et al ., ). Comparison of transcript profiles induced by SCN in resistant versus susceptible soybean cultivars also indicates that BIK1 and RBOHD induction correlate with cyst nematode resistance (Matsye et al ., ; Wan et al ., ).…”