University of Kentucky

Poster Title

Role of Circadian Rhythm in Plant-Virus Interaction

Presenter Information

Timothy Hoey, University of Kentucky

Institution

University of Kentucky

Abstract

Recently it has been shown that light patterns play some role in the signaling of host defense mechanisms. Plants have two types of photoreceptors that, in general, are classified based on whether they absorb red/far-red or blue light spectrums. The red/far-red and blue light absorbing photoreceptors are called phytochromes and cryptochromoes/phototropins, respectively. Interestingly, besides development, these photoreceptors are also known to participate in circadian rhythms, as well as defense against microbial pathogens. Plants use a variety of mechanisms to defend themselves against microbial pathogens. One of these involves recognition of pathogens via specialized plant proteins known as resistance (R) proteins. These R proteins act via recognizing one of the pathogen-encoded proteins. Recent results showed that blue-light photoreceptors cryptochromes and phototropins are required for the stability of R protein HRT, which allow the model plant Arabidopsis (Arabidopsis thaliana) to recognize and mount immune response turnip crinkle virus (TCV). Induction of HRT-mediated defense restricts TCV to localized point of entry and thereby prevents its spread. However, mutations in either cryptochrome (CRY2) and phototropin (PHOT2) causes degradation of HRT, which resulted in increased viral replication and spread. Since CRY2 and PHOT2 also play a role in circadian rhythms it is possible that circadian rhythm might also play a role in plant defense against viral pathogens. We have shown that circadian rhythms have specific impacts on plant viral interactions in the Arabidopsis- TCV pathosystem.

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Role of Circadian Rhythm in Plant-Virus Interaction

Recently it has been shown that light patterns play some role in the signaling of host defense mechanisms. Plants have two types of photoreceptors that, in general, are classified based on whether they absorb red/far-red or blue light spectrums. The red/far-red and blue light absorbing photoreceptors are called phytochromes and cryptochromoes/phototropins, respectively. Interestingly, besides development, these photoreceptors are also known to participate in circadian rhythms, as well as defense against microbial pathogens. Plants use a variety of mechanisms to defend themselves against microbial pathogens. One of these involves recognition of pathogens via specialized plant proteins known as resistance (R) proteins. These R proteins act via recognizing one of the pathogen-encoded proteins. Recent results showed that blue-light photoreceptors cryptochromes and phototropins are required for the stability of R protein HRT, which allow the model plant Arabidopsis (Arabidopsis thaliana) to recognize and mount immune response turnip crinkle virus (TCV). Induction of HRT-mediated defense restricts TCV to localized point of entry and thereby prevents its spread. However, mutations in either cryptochrome (CRY2) and phototropin (PHOT2) causes degradation of HRT, which resulted in increased viral replication and spread. Since CRY2 and PHOT2 also play a role in circadian rhythms it is possible that circadian rhythm might also play a role in plant defense against viral pathogens. We have shown that circadian rhythms have specific impacts on plant viral interactions in the Arabidopsis- TCV pathosystem.