The bacterial effector AvrRxo1 inhibits vitamin B6 biosynthesis to promote infection in rice.


Xanthomonas oryzae pv. oryzicola (Xoc), which causes rice bacterial leaf streak, invades leaves mainly through stomata, which are often closed as a plant immune response against pathogen invasion. How Xoc overcomes stomatal immunity is unclear. Here, we show that the effector protein AvrRxo1, an ATP-dependent protease, enhances Xoc virulence and inhibits stomatal immunity by targeting and degrading rice OsPDX1 (pyridoxal phosphate synthase), thereby reducing vitamin B6 (VB6) levels in rice. VB6 is required for the activity of aldehyde oxidase, which catalyzes the last step of abscisic acid (ABA) biosynthesis, and ABA positively regulates rice stomatal immunity against Xoc. Thus, we provide evidence supporting a model in which a major bacterial pathogen inhibits plant stomatal immunity by directly targeting VB6 biosynthesis and consequently inhibiting the biosynthesis of ABA in guard cells to open stomata. Moreover, AvrRxo1-mediated VB6 targeting also explains the poor nutritional quality, including low VB6 levels, of Xoc-infected rice grains.





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Publication Info

Liu, Haifeng, Chongchong Lu, Yang Li, Tao Wu, Baogang Zhang, Baoyou Liu, Wenjie Feng, Qian Xu, et al. (2022). The bacterial effector AvrRxo1 inhibits vitamin B6 biosynthesis to promote infection in rice. Plant communications, 3(3). p. 100324. 10.1016/j.xplc.2022.100324 Retrieved from

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Sheng-Yang He

Benjamin E. Powell Distinguished Professor of Biology

Interested in the fascinating world of plants, microbes or inter-organismal communication and co-evolution? Please contact Prof. Sheng-Yang He (;

Millions of years of co-evolution between plants and microbes have resulted in an intricate web of attack, counter-attack, decoy, and hijacking mechanisms in biology. Moreover, co-evolution between plants and microbes is greatly impacted by ongoing climate change. In our lab, we probe “host-microbe-climate” interactions to answer the following fundamental questions: (1) How do microbial pathogens infect a susceptible host? (2) How do plants select beneficial microbiomes to ensure health? (3) How do climate conditions impact disease and immunity?      

We use contemporary methods to address these questions, including those commonly used in molecular genetics, genomics, biochemistry, cell biology, bioinformatics, microbiology, plant biology, co-evolution and infectious disease biology.    

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