Methyl Jasmonate Strengthens Wheat Plants Against Root and Crown Rot Pathogen Fusarium culmorum Infection

Abstract

Root and crown rot of wheat, caused by Fusarium culmorum (Fc), is a serious disease worldwide, particularly in Iran. Currently, the mechanisms underlying resistance to Fusarium-caused diseases are still unknown. Methyl jasmonate (MeJA) has been identified as a vital cellular regulator, and the effect of exogenous MeJA application during wheat-Fc interaction has not been studied previously at the molecular level. This study, using realtime quantitative PCR, was carried out to determine the expression of seven host defense-associated genes consisting of PR3, PR4, PR5, TaPERO, LOX, PAL and cytochrome P450 gene (CYP709C1) at 48, 72 and 96 h after Fc-inoculation (hai) and to investigate the relationship between the induced resistance by MeJA application and the gene expression patterns. The results showed that several genes were induced earlier (48 hai) and to higher levels in the resistant cv. Sumai3 than in susceptible cv. Falat. Many Fc-induced genes were also activated and induced by MeJA particularly during the later stages of infection; however, in contrast to defense-gene induction by the pathogen, there was not a general trend of higher induction in Sumai3 compared to Falat following this chemical treatment. The chemically induced protection significantly reduced the development of necrotic symptoms in both cultivars over a 3-week period after inoculation; however, this reduction was greater in Falat than in Sumai3 relative to the controls. Surprisingly, the expression of these genes was also expressed in crown tissue that had not yet been in contact with the fungus, signifying that a form of systemic response was taking place in this interaction. This is the first work reporting the effect of timing application of MeJA during Fc infection and comparing the defense-related gene expression between root and crown tissues of wheat genotypes. Moreover, soildrench application of MeJA resulted in strong induction, verifying the success of this application method in systemically activating JA signaling for the first time. These results provided important intimations for designing strategies to curtail diseases caused by Fusarium.

Induction of basal resistance by methyl jasmonate against Fusarium culmorum in bread wheat

“…S1). Our previous research has reported that exposure of wheat genotypes to MeJA during the later stages of infection beginning at 1 dpi and later promoted resistance, while when applied prior to inoculation or at the time of fungal inoculation, attenuated FCRR resistance (Motallebi et al 2015b). Whereas, present results using MeJA treatment at 6 hai clearly indicate that the induction of defense genes in wheat occurred at the beginning of the necrotrophic stage in a genotype dependent manner.…”

“…Even if there are several studies on wheat-pathogen interaction (Desmond et al 2006;Makandar et al 2010;Beccari et al 2011;Makandar et al 2012;Motallebi et al 2015b), little is known about the contribution of JA derivatives, such as MeJA, to the resistance mechanisms. In the current work, several genes expression has been investigated to better understand the differences between susceptible and tolerant wheat genotypes infected by F. culmorum.…”

“…In spite of the importance of FCRR disease in agriculture, only few studies have dealt with it and the basis for resistance against FCRR is still unknown. In our previous research, we have demonstrated the effects of MeJA on wheat defense gene expression during the later stages of Fc-infection in wheat (Motallebi et al 2015b). The data suggested that MeJA is a potent inducer of defense gene expression particularly 2 days post inoculation (2 dpi) which was coincided with necrotrophic stage.…”

“…Indeed, the previous work (Motallebi et al 2015b) has been extended to this study, showing that this differential response exists in wheat genotypes between the beginning of the necrotrophic and during necrotrophic stage of F. culmorum infection. Real-time quantitative PCR has been used to compare the systemic expression of wheat defenseassociated genes such as PAL, LOX, cytochrome P450 gene (CYP709C1), PR3, PR4, and peroxidase (PR9) in two bread wheat cultivars, Falat and Sumai3 with different resistance levels to FCRR.…”

Plant-Mediated Systemic Interactions Between Pathogens, Parasitic Nematodes, and Herbivores Above- and Belowground

“…In rice, root SA application results in higher leaf concentrations of phytoalexins such as oryzalexins and momilactone A (26). Similarly, exogenous root application of MeJA (methyl jasmonate) induces expression of defense-associated genes, including a 13-lipoxygenase gene (LOX), PR-3, and PR-4 in wheat crowns and reduces crown symptoms of the pathogen Fusarium culmorum (114). Exogenous shoot application of both SA and JA contributes to resistance to clubroot disease caused by the protist Plasmodiophora brassicae in A. thaliana (90).…”