Cornell University researchers have figured out how the tomato pathogen that causes bacterial in speck in tomatoes has evolved to interfere with the plant's immune system.

In the journal Cell Host & Microbe, plant pathology professor Greg Martin discussed what he called a molecular arms race between the tomato plant and Pseudomonas syringae, according to a news release.

The research was conducted at Cornell's Boyce Thompson Institute for Plant Science in conjunction with Tsinghua University in Beijing, China.

Researchers shed light on causal agent of tomato bacterial speck

Martin found that the pathogen injects a protein—AvrPtoB—into plant cells that interferes with the plant's immune response.

As a result, the bacteria is able to multiply.

Martin also reported how the protein binds and interferes with another protein, BAK1, which acts with immune receptors to activate plant defenses.

Some tomato varieties are resistant to Pseudomonas syringae because they have proteins that detect AvrPtoB and mount a defense.

By gaining a better understand about how the pathogen infects tomatoes, it is hoped that breeders will be able to develop speck-resistant varieties.