Chinese-international research team unlocks new strategy against 'crop killer'

A joint Chinese-international research team has decoded how the destructive plant pathogen Xanthomonas acquires specialized nutrients from host tissues, offering a novel approach to combat crop diseases caused by this bacterium.

Xanthomonas poses a major threat to agriculture globally, capable of infecting over 400 crop species and causing severe diseases. It spreads rapidly, is difficult to control and many crops, including rice, lack natural resistance.

The study, published online in Science, reveals a key survival strategy of the pathogen. Corresponding authors are from Southwest University, Jilin Agricultural University and Duke University, with contributing researchers from institutions including the University of California and Seoul National University.

According to Wang Shanzhi, first author of the paper, when Xanthomonas infects rice, it secretes a "nutrient-synthesizing enzyme" called AvrBs2 into plant cells. Inside the host cell, this enzyme utilizes plant nutrients to produce a cyclic sugar phosphate compound named xanthosan.

The pathogen then reabsorbs and degrades xanthosan through a specialized transport protein and degrade enzyme, thereby obtaining essential nutrients for its growth and reproduction.

"This shows that Xanthomonas oryzae establishes a "synthesis-transport-utilization" nutrient pipeline within rice, continuously plundering host resources to feed itself," Wang explained. "Blocking this nutrient acquisition pathway could therefore enhance rice resistance to the bacterial disease."

Based on this finding, the team proposed a new "anti-xanthomonadin" breeding strategy. Experiments confirmed that blocking the pathogen's use of xanthosan weakens its virulence. Transgenic rice engineered with this trait exhibited enhanced disease resistance and showed no adverse effects on growth or metabolism, demonstrating its strong application potential.

Since AvrBs2 is common across many Xanthomonas pathogens, this approach could also help control other bacterial diseases like citrus canker and tomato bacterial spot, providing new support for sustainable agriculture, according to the researchers.