Involvement of Salicylate and Jasmonate Signaling Pathways in Arabidopsis Interaction with Fusarium graminearum

Abstract

Summary Fusarium graminearum is the principal causative agent of Fusarium head blight (FHB), a devastating disease of wheat and barley. This fungus can also colonize Arabidopsis thaliana. Disease resistance was enhanced in transgenic wheat and Arabidopsis plants that constitutively over-express the NONEXPRESSOR OF PR GENES 1 (NPR1) gene, which regulates salicylic acid (SA) signaling and modulates the activation of jasmonic acid (JA)-dependent defenses. Here, we provide several lines of evidence that reveal an important role for SA and JA signaling in Arabidopsis defense against F. graminearum. SA level was elevated in fungus-inoculated leaves and SA application and biologically activated systemic acquired resistance enhanced resistance. Furthermore, the disruption of SA accumulation and signaling in the sid2 mutant and NahG transgenic plant, and the npr1 and wrky18 mutants, respectively, resulted in heightened susceptibility to this fungus in leaves and inflorescence. JA signaling was activated in parallel with SA signaling in the fungus-challenged plants. But, the hyper-resistance of the JA pathway mutants, opr3, coi1 and jar1 indicates that this pathway contributes to susceptibility. Genetic and biochemical experiments indicate that the JA pathway promotes disease by attenuating the activation of SA signaling in fungus-inoculated plants. However, the hyper-susceptibility of the jar1 npr1 double mutant compared to the npr1 mutant suggests that JAR1 also contributes to defense, signifying a dichotomous role of JA and JAR1-dependent mechanism in this interaction.

Plant defense response against Fusarium oxysporum and strategies to develop tolerant genotypes in banana

“…Recently a novel transcription factor, LBD20 (Lateral Organ Boundaries Domain) gene which on its disruption led to increased resistance in Arabidopsis to Fox was found and this suggests that LBD20 is a Fusarium susceptibility gene that appears to regulate components of JA-signaling downstream of COI1 and MYC2 transcription factors (Thatcher et al 2012a). JA signaling has a dichotomous involvement in the Arabidopsis interaction with F. graminearum, contributing to the attenuation of SA signaling during the early stages of infection and promotion of defense against F. graminearum during later stages of infection (Makandar et al 2010). Similarly in another study involving Arabidopsis, a complex interaction between SA/NPR1 and JA signaling regulates basal resistance against Fusarium head blight (FHB), because exposure to MeJA vapors either prior to fungal inoculation or during the early stages of fungal infection attenuated AtNPR1-conferred FHB resistance suggesting that during the early stages of infection, JA signaling attenuates SA/NPR1-determined defense signaling (Makandar et al 2012).…”

Fusarium-plant interaction: state of the art - a review

“…SA mutants impaired in the SA signalling have shown susceptibility to this pathogen; on the other hand, SA applications increased resistance to F. graminearum. Moreover, JA signalling contributes to F. graminearum susceptibility by SA signalling attenuation during the initial infection but promoting resistance as the disease progresses (Makandar et al 2010(Makandar et al , 2012. Not only SA inhibits the F. graminearum growth in acidic conditions but also this pathogen has the ability to metabolize SA to SA biosynthesis intermediates such as catechol in basic growth conditions.…”

The possible roles of <i>AtERF71</i> in the defense response against the <i>Fusarium graminearum</i>

“…It is established that F. graminearum can infect both the leaves and flower organs of Arabidopsis thaliana (Makandar et al 2010;Urban et al 2002). Therefore, this plant has been investigated for signaling pathways that may lead to plant disease resistance against Fusarium species such as F. graminearum.…”

“…Therefore, this plant has been investigated for signaling pathways that may lead to plant disease resistance against Fusarium species such as F. graminearum. This resistance was positively controlled via the salicylic acid (SA)-dependent signaling pathway in Arabidopsis and wheat plants (Makandar et al 2010(Makandar et al , 2012. On the contrary, ethylene (ET) and jasmonic acid (JA) negatively regulated host plant resistance against F. graminearum (Chen et al 2009;Makandar et al 2010).…”

“…This resistance was positively controlled via the salicylic acid (SA)-dependent signaling pathway in Arabidopsis and wheat plants (Makandar et al 2010(Makandar et al , 2012. On the contrary, ethylene (ET) and jasmonic acid (JA) negatively regulated host plant resistance against F. graminearum (Chen et al 2009;Makandar et al 2010). Although ET is a simple gaseous hormone, it plays multiple roles in regulating plant growth and development, such as vegetative growth, the senescence of leaves, flowers, and fruits (Iqbal et al 2017), and adaptation to abiotic stresses, such as water-deficits (Gu et al 2007) and salinity stress (Tao et al 2015).…”