Researchers at the CAS Center for Excellence in Molecular Plant Sciences, led by Alberto Macho, have recently shown that heterologous expression of immune receptors confers novel recognition of a devastating bacterial pathogen. The resulting article, entitled “Heterologous expression of Arabidopsis FLS2 in Nicotiana benthamiana confers responsiveness to Ralstonia flg22 and activation of anti-bacterial immunity” was published online in Plant Biotechnology Journal on July 25th.

Bacteria within the Ralstonia solanacearum species complex cause devastating diseases in numerous crops, including tomato, potato, banana, eggplant, and pepper, among others, leading to important losses in food production and industrial supply. Despite extensive efforts to enhance plant tolerance to disease caused by Ralstonia, efficient and sustainable approaches are still missing.

The recognition of pathogen-associated molecular patterns (PAMPs), such as bacterial flagellin, is a critical component of plant innate immunity. FLS2, a leucine-rich repeat receptor kinase from Arabidopsis thaliana, forms a complex with the co-receptor BAK1 upon perception of flg22, triggering immune responses. However, some bacterial pathogens evade recognition by modifying their flg22 sequences. R. solanacearum, for instance, possesses a polymorphic flg22 peptide (flg22Rso) that is not recognized by the FLS2 receptors of most model species, including Arabidopsis and N. benthamiana.

In this study, the authors report that the introduction of Arabidopsis FLS2 into N. benthamiana renders this plant capable of perceiving flg22Rso and initiating immune signaling. The heterologously expressed AtFLS2 associates with the native N. benthamiana SERK proteins (NbSERKs), enabling the formation of a functional receptor complex. This interaction leads to robust immune activation and limits bacterial proliferation, demonstrating that AtFLS2-mediated recognition of flg22Rso is sufficient to trigger protective responses in N. benthamiana.

This work highlights the potential of cross-species PRR engineering as a strategy for enhancing disease resistance in crops, particularly against pathogens that have evolved to evade detection by native immune receptors.

The study was conducted by Meng Li, Yujiao Chen, Yali Wei, and Alberto P. Macho, and was supported by the Chinese Academy of Sciences and the University of the Chinese Academy of Sciences.

Link to the article: https://doi.org/10.1111/pbi.70255

Contact: 

Dr. Alberto P. Macho, Principal Investigator

Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences

Email: alberto.macho@cemps.ac.cn

Heterologous expression of Arabidopsis FLS2 in Nicotiana benthamiana confers responsiveness to Ralstonia flg22 and activation of anti-bacterial immunity