Sulfated peptides serve as molecular mimics that facilitate pathogen virulence

这项工作将促进对细菌和线虫如何感染植物的理解。具体地说，研究人员将研究一组预计在植物生长、发育和防御中发挥重要作用的分子，这些分子对作物质量和产量至关重要。由于细菌和线虫侵染植物的范围很广，而且这些分子几乎存在于所有农作物中，因此成功完成拟议的目标将对美国农业具有广泛的意义。这项工作将为博士后研究人员提供跨学科培训，并在遗传学、蛋白质组学和分子生物学的尖端技术方面为本科生和高中生提供指导。不同种类的植物病原体分泌的分子模仿宿主产生的分子，作为操纵宿主细胞功能的一种策略。例如水稻病原菌Xanthomonas oryzae PV。稻米(Xoo)分泌一种名为RaxX的微生物多肽，这是激活水稻Xa21介导的免疫所必需的。RaxX与含有硫化酪氨酸(PSY)家族的植物多肽序列相似，PSY家族对植物的生长和发育至关重要。RaxX在多种黄单胞菌中都是保守的，并且与宿主PSY肽一样能促进根的生长。RaxX的零突变降低了Xoo对缺乏Xa21免疫受体的水稻植株的毒力。综上所述，这些结果表明RaxX作为细菌毒力因子发挥作用。研究人员发现，南方根结线虫的基因组也被预测包含PSY样肽(名为MigPSY)的基因。在拟南芥中，PSY促进细胞的增殖和扩张。考虑到线虫取食部位的形成需要大量的宿主细胞扩张和细胞壁修饰，我们假设根结线虫在取食部位形成过程中利用MigPSY征用宿主PSY信号来调控细胞的增殖和重塑。这项提议旨在检验这一假设。该项目将(1)分析PSY样多肽的表达和生物活性，(2)调查PSY样信号如何有助于成功的细菌和线虫感染，以及(3)识别参与这种信号反应的植物受体。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

This work will advance understanding of how bacteria and nematodes infect plants. Specifically, the researchers will study a group of molecules that are predicted to play important roles in plant growth, development, and defense, which are critical to crop quality and yield. Because bacteria and nematodes infect a wide range of plants and these molecules are present in virtually all crop plants, successful completion of the proposed objectives will have broad significance to U.S. agriculture. This work will provide interdisciplinary training of postdoctoral researchers and mentoring of undergraduate and high school students on cutting-edge technologies of genetics, proteomics, and molecular biology. Diverse species of plant pathogens secrete molecules that mimic those produced by the host as a strategy to manipulate host cellular function. For example, the rice pathogen Xanthomonas oryzae pv. oryzae (Xoo) secretes a microbial peptide called RaxX, which is required for activation of rice XA21-mediated immunity. RaxX shares sequence similarity to the plant peptide containing sulfated tyrosine (PSY) family, which is critical for plant growth and development. RaxX is conserved in multiple Xanthomonas species and can promote root growth to the same extent as the host PSY peptide. Null mutation of raxX compromises the virulence of Xoo on rice plants that lack the XA21 immune receptor. Together, these results suggest that RaxX functions as a bacterial virulence factor. The researchers discovered that the genomes of the root-knot nematode, of the Meloidogyne incognita group, are also predicted to contain genes for PSY-like peptides (named MigPSY). In Arabidopsis, PSY promotes cellular proliferation and expansion. Considering that formation of the nematode feeding site requires extensive host cell expansion and cell wall modifications, we hypothesize that root-knot nematodes utilize MigPSY to commandeer host PSY signaling to manipulate cellular proliferation and remodeling during feeding site formation. This proposal aims to test this hypohtesis. This project will (1) analyze the expression and bioactivity of PSY-like peptides, (2) investigate how PSY-like signaling contributes to successful bacterial and nematode infection, and (3) identify plant receptors involved in this signaling response.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.