In nature, plants are constantly exposed to a variety of complex and variable threats. Among them, pathogenic microorganisms, such as bacteria, fungi and oomycetes, pose a great challenge to global food security as a class of biotic stresses that seriously threaten plant life. However, did you know that just like humans, plants have their own immune systems? In the process of co-evolution between pathogens and hosts, plants have developed multiple mechanisms to defend themselves against pathogenic invasion.
Even if the pathogen escapes the physical barrier of the plant and invades, the plant will not await their doom. In order to prevent further infection of pathogens, plants will produce various defense reactions. Hypersensitive reaction (HR) is one of the most common immune responses and can quickly lead to necrosis around the infected area, which establishes a zone of isolation to prevent the pathogen from colonizing or expanding in the plant.
In agricultural production, infection of crops by pathogens can cause severe yield losses. Traditional crop production systems rely heavily on the extensive use of chemical pesticides aimed at killing pathogenic microbes. But this has not only resulted in serious environmental pollution, but also in many problems such as drug resistance and crop damage. Among the many approaches to overcome plant diseases in recent years, targeted use of inherent plant disease defense mechanisms has become a more popular strategy. Plant immune inducers are those that have no direct fungicidal or antiviral activity but are able to induce the plant immune system so that the plant acquires or improves resistance to pathogens. This immune inducer ultimately gives the plant the ability to resist foreign pathogens.
This study investigates a protein-based immune inducer that enhances broad-spectrum resistance in plants. It has been identified from the major wheat pathogen Fusarium graminearum. Fg02685 is a small, secreted protein without a conserved domain that can be delivered extracellularly to induce cell death in the plant apoplast region.
It was found that Fusarium graminearum strains that were genetically modified to be incapable of producing Fg02685 (ΔFg02685 mutants) reduce fungal growth and disease development in infected wheat heads, exhibiting the importance of this protein for pathogen infection (see below).
Surprisingly, a short (32 amino acid) peptide, FgNP32, at the N-terminal of Fg02685 also activates the plant immune defence response (see inset graph above).
What’s more, FgNP32 can enhance disease resistance, not only for wheat, but also in many plants such as tobacco and soybean, seemingly inducing a plant immune response (title image). It provides a new environmentally friendly option to control crop disease.
Qiang Xu, Su Hu, Minxia Jin, Yangjie Xu, Qiantao Jiang, Jian Ma, Yazhou Zhang, Pengfei Qi, Guoyue Chen, Yunfeng Jiang, Youliang Zheng and Yuming Wei published this article in Molecular Plant Pathology:
TITLE IMAGE: FgNP32 induces disease resistance in plants. This is an image of tobacco (Nicotiana benthamiana) leaves infected with a pathogen (Phytophthora parasitica var. nicotianae). The left leaf shows how disease spreads rapidly over 2 days – shown as green spreading from the circular inoculation point. In contrast, the treated leaf on the right (with FgNP32 peptide, 12 hours earlier) shows a smaller spread of disease. (The white bars represent a 1cm scale.) All images used with permission of the author.
