Abstract
Flavonoids are well known for the coloration of plant organs to protect UV and ROS and to attract pollinators as well. Flavonoids also play roles in many aspects of physiological processes including pathogen resistance. However, the molecular mechanism to explain how flavonoids play roles in pathogen resistance was not extensively studied. In this study, we investigated how naringenin, the first intermediate molecule of the flavonoid biosynthesis, functions as an activator of pathogen resistances. The transcript levels of two pathogenesis-related (PR) genes were increased by the treatment with naringenin in Arabidopsis. Interestingly, we found that naringenin triggers the monomerization and nuclear translocation of non-expressor of pathogenesis-related genes 1 (NPR1) that is a transcriptional coactivator of PR gene expression. Naringenin can induce the accumulation of salicylic acid (SA) that is required for the monomerization of NPR1. Furthermore, naringenin activates MPK6 and MPK3 in ROS-dependent, but SA-independent manners. By using a MEK inhibitor, we showed that the activation of a MAPK cascade by naringenin is also required for the monomerization of NPR1. These results suggest that the pathogen resistance by naringenin is mediated by the MAPK- and SA-dependent activation of NPR1 in Arabidopsis.
Highlights
Flavonoids are secondary metabolites widely distributed in plants
To explore whether non-expressor of pathogenesis-related genes 1 (NPR1) plays a crucial role in naringenininduced resistance, we investigated the effects of naringenin on pathogen resistance against Pst DC3000 in npr1-1 plant
Flavonoids including naringenin are accumulated after infection with biotrophic pathogen Plasmodiophora brassicae, Pseudomonas siringae pv
Summary
Flavonoids are secondary metabolites widely distributed in plants. Flavonoids have roles in many facets of plant physiology (Buer et al, 2010). Major roles of flavonoids are UV protectants (Shirley, 1996), antioxidants and scavengers of reactive oxygen species (Rice-Evans, 2001). The other roles of flavonoids include pollinator attractants (Mol et al, 1998), root nodulation (Mandal et al, 2017), allelopathy (Hassan and Mathesius, 2012) and auxin transport inhibitor (Peer and Murphy, 2007). The previous study revealed that flavonoids act in resistance against pathogens and herbivores (Treutter, 2005). Naringenin is one of the major flavonoids which was broadly distributed in citrus fruits and vegetables such as grapefruit, lemon, oranges and tomatoes (Manchope et al, 2017). Naringenin is accumulated by infected biotrophic pathogen Plasmodiophora brassicae and Naringenin Induces Pathogen Resistance
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
