A Review on Plant-Pathogen Interactions

Author: Prashanth Kumar A.

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Abstract

Plants evolved nucleotide-binding domains (NLRs) that recognized effectors of pathogens, which resulted in a second layer of immune effector-triggered immunity (ETI). Biotrophic pathogens manipulate host physiological activities to obtain nutrients from living host cells and tissues, and hemibiotrophic pathogens secrete effectors that suppress host immunity and re-program host physiology to favor pathogen colonization. Plants have membrane-lined pores called plasmodesmata, which connect adjacent cells and facilitate symplast communication. Pathogenic microorganisms disrupt the actin cytoskeleton in plant cells and create hydrophobic spaces between pathogen-host plants to grow in the air. Plant PRR recognizes degraded fragments of bacteria and plant cell walls as PAMPs or DAMPs to trigger immunity. Pathogens use various effectors to suppress PAMP-triggered immunity, including protecting the mycelium from degradation by plant chitinases. Plants secrete antimicrobial proteins and compounds to fight infection by pathogens, but effector proteins secreted by pathogens degrades these compounds. Autophagy is an essential part of plant immunity to different pathogens. The black cob pathogen Sporisorium reilianum and the pathogen may act differently, suggesting that the Tin2 of U. maydis may be newly functionalized. Phytophthora sojae alters protein localization in the host plant cytosol to produce functional abnormalities and pathogenic effects. Microbial manipulation of the host may be achieved by directly targeting ER stress regulators, restricting defense-related vesicle transport as a virulence factor, and inhibiting the interaction between NPR1 and TGA transcription factors, reducing PR gene expression. Some pathogens inhibit the host's RNA silencing process to promote infection, and others neutralize or inhibit ROS production. Plants detect pathogens using their NLR and PRR, and kill cells with their effectors. Effectors are essential elements of plant-pathogen interactions. Although many effectors have been identified and characterized, there are likely still numerous unknown effectors lurking beneath the surface, waiting to be discovered.

Keywords

Effectors, Plasmodesmata, symplast, Autophagy and hydrophobic spaces

Conclusion

Effectors are essential elements of plant-pathogen interactions. They exert their pathogenic effects primarily by targeting R proteins in the plant. By understanding the intricate interplay between effectors and R proteins, we can uncover new avenues for developing effective strategies to protect plants from devastating diseases. Although current research on effectors is quite prolific, there is still much to uncover about their mechanisms of action. One notable model in this field is the iceberg model proposed by Thordal-Christensen (Thordal- Christensen et al., 2020). This model suggests that while many effectors have been identified and characterized, there are likely still numerous unknown effectors lurking beneath the surface, waiting to be discovered. The iceberg model serves as a reminder that our current understanding of effectors is only the tip of the iceberg, and there is still much more to explore and unravel in this fascinating area of research. By continuing to investigate effectors and their mechanisms of action, scientists can further expand our knowledge and potentially uncover new therapeutic targets or strategies for combating diseases caused by pathogenic effectors.

References

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How to cite this article

Prashanth Kumar A. (2023). A Review on Plant-Pathogen Interactions. Biological Forum – An International Journal, 15(3): 784-792.