A harpin elicitor induces the expression of a coiled-coil nucleotide binding leucine rich repeat (CC-NB-LRR) defense signaling gene and others functioning during defense to parasitic nematodes

Abstract

The bacterial effector harpin induces the transcription of the Arabidopsis thaliana NON-RACE SPECIFIC DISEASE RESISTANCE 1/HARPIN INDUCED1 (NDR1/HIN1) coiled-coil nucleotide binding leucine rich repeat (CC-NB-LRR) defense signaling gene. In Glycine max, Gm-NDR1-1 transcripts have been detected within root cells undergoing a natural resistant reaction to parasitism by the syncytium-forming nematode Heterodera glycines, functioning in the defense response. Expressing Gm-NDR1-1 in Gossypium hirsutum leads to resistance to Meloidogyne incognita parasitism. In experiments presented here, the heterologous expression of Gm-NDR1-1 in G. hirsutum impairs Rotylenchulus reniformis parasitism. These results are consistent with the hypothesis that Gm-NDR1-1 expression functions broadly in generating a defense response. To examine a possible relationship with harpin, G. max plants topically treated with harpin result in induction of the transcription of Gm-NDR1-1. The result indicates the topical treatment of plants with harpin, itself, may lead to impaired nematode parasitism. Topical harpin treatments are shown to impair G. max parasitism by H. glycines, M. incognita and R. reniformis and G. hirsutum parasitism by M. incognita and R. reniformis. How harpin could function in defense has been examined in experiments showing it also induces transcription of G. max homologs of the proven defense genes ENHANCED DISEASE SUSCEPTIBILITY1 (EDS1), TGA2, galactinol synthase, reticuline oxidase, xyloglucan endotransglycosylase/hydrolase, alpha soluble N-ethylmaleimide-sensitive fusion protein (α-SNAP) and serine hydroxymethyltransferase (SHMT). In contrast, other defense genes are not directly transcriptionally activated by harpin. The results indicate harpin induces pathogen associated molecular pattern (PAMP) triggered immunity (PTI) and effector-triggered immunity (ETI) defense processes in the root, activating defense to parasitic nematodes.

Mitogen activated protein kinases function as a cohort during a plant defense response

“…Experiments presented here show that G. max MAPKs (MAPKs) identified to be expressed within parasitized root cells undergoing the process of defense to the root pathogenic nematode Heterodera glycines often presage their function in defense. Experiments show the relationship between PTI and ETI and the defense MAPKs to prior published work (Matsye et al 2011Pant et al 2014Pant et al , 2015Sharma et al 2016;McNeece et al 2017;Aljaafri et al 2017;. As presented in earlier experiments, PTI has been studied here by examining ENHANCED DISEASE SUSCEPTIBILITY1 (EDS1) and LESION SIMULATING DISEASE1 (LSD1) (Dietrich et al 1997;Aarts et al 1998;Falk et al 1999;Pant et al 2014Pant et al , 2015Matuszkiewicz et al 2018).…”

“…Among the 229 induced genes were the G. hirsutum NDR1 (Gh-NDR1) and MPK7 (CM081B01) (Miao et al 2010). Consequently, the involvement of harpin during G. max defense to different parasitic nematodes, including H. glycines, Meloidogyne incognita and Rotylenchulus reniformis, is consistent with its important role in defense signaling (Gopalan et al 1996;Aljaafri et al 2017).…”

“…Analyses having been performed in G. max show components of two different receptor systems, functioning in PTI and ETI, act in defense to H. glycines parasitism McNeece et al 2017;Aljaafri et al 2017). Each of these receptor systems transduce signals through the MAPK cascade (Desikan et al 2000;Zhang et al 2011;Couto et al 2016).…”

“…ETI has been studied by examining the relationship between treatment with bacterial elicitor harpin and MAPK gene expression . The experiments presented here then focus on G. max homologs of the ETI genes NON-RACE SPECIFIC DISEASE RESISTANCE 1/HARPIN INDUCED1 (NDR1/HIN1) and BOTRYTIS INDUCED KINASE1 (BIK1) (Wei et al 1992;Century et al 1995Century et al , 1997Gopalan et al 1996;Veronese et al 2006;McNeece et al 2017;Aljaafri et al 2017). Furthermore, transcriptional analyses show that the transgenic MAPK lines affect the expression of different suites of proven defense genes Pant et al 2014;Sharma et al 2016;McNeece et al 2017).…”

Biological control potential of plant growth‐promoting rhizobacteria suppression of Meloidogyne incognita on cotton and Heterodera glycines on soybean: A review

“…Aljaafri et al. () found that a harpin elicitor can function to turn on plant defences in H. glycines in soybean, and M. incognita and R. reniformis in cotton in susceptible cultivars.…”