BRC-BIO: Familiarity with friends: Transgenerational effects as a mechanism for partner choice in the legume-rhizobia mutualism

BRC-BIO：与朋友的熟悉度：跨代效应作为豆科植物-根瘤菌互利共生中伙伴选择的机制

• 批准号: 2217901
• 负责人: Chandra Jack
• 金额: $ 45.29万
• 依托单位: Clark University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-09-01 至 2025-08-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2217901&HistoricalAwards=false
• 关键词: BRC; BIO; Familiarity; friends; Transgenerational

Mutualisms are of fundamental importance and found at every organismal level, where they facilitate the fitness and survival of the interacting partners. For example, nitrogen is an essential nutrient required for plant growth, yet the most abundant form is inaccessible to plants, making it a limiting resource. Legumes have overcome this limitation by forming beneficial partnerships with symbiotic bacteria, known as rhizobia, where they receive usable nitrogen in exchange for carbon metabolites. The problem is that prior to establishing the relationship, the plant has no information about the quality of its partner. Choosing the right mutualistic bacterial partner, while excluding parasitic bacteria, is essential because the process to form the mutualistic relationship requires the plant to expend energy that could otherwise be used for growth. Many legume species already show some degree of specificity using signaling to limit partnership with compatible rhizobia species. Once the partnership is initiated, there is additional molecular signaling that triggers the plant immune system. Either type of signaling may leave an imprint or memory on the host plant that is specific to individual rhizobia strains. This study examines the hypothesis that this memory may be heritable and help future generations of the host plant choose beneficial strains due to familiarity, giving a better understanding of non-genetic heritability and providing insight into the maintenance of mutualistic relationships. This project also provides undergraduate students with funded research experience, which has been shown to improve diversity and increase retention in STEM.The origination and maintenance of mutualisms presents an evolutionary conundrum as both partners are expected to act in their own self-interest. As with all mutualisms, there is a risk of the host being exploited by their partner leading to the breakdown of the relationship. The ability to choose a faithful and beneficial partner can stabilize the partnership. However, the mechanism that allows for partner choice has not yet been uncovered in the legume-rhizobia mutualism, despite evidence that host plants are able to preferentially nodulate with more beneficial partners. This project examines the prediction that the selected partner will likely be determined through a combination of genetic (host plant and rhizobia genes), epigenetic and environmental elements. Using the bearded clover, Trifolium barbigerum, the research team will determine whether transgenerational effects from previous generations can influence the host plant’s choice of symbiotic partner. This project will quantify nodule occupancy to determine whether previous exposure to a strain and its efficacy inform host plant selection using a combination of fluorescent labeling, qPCR and metabarcoding to distinguish rhizobia at the strain level.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.

互惠关系是至关重要的，存在于每一个生物层面，它们促进了相互作用的伙伴的适应和生存。例如，氮是植物生长所必需的营养物质，但最丰富的形式是植物无法获得的，使其成为一种有限的资源。豆科植物通过与被称为根瘤菌的共生细菌形成有益的伙伴关系来克服这一限制，在那里它们获得可用的氮以换取碳代谢物。问题是，在建立关系之前，工厂没有关于其合作伙伴质量的信息。在排除寄生细菌的同时，选择合适的共生细菌伙伴是至关重要的，因为形成共生关系的过程需要植物消耗本来可以用于生长的能量。许多豆科植物已经显示出一定程度的特异性，利用信号来限制与相容根瘤菌物种的伙伴关系。一旦伙伴关系启动，就会有额外的分子信号触发植物免疫系统。任何一种类型的信号都可能在寄主植物上留下印记或记忆，这是特定于单个根瘤菌菌株的。本研究检验了这种记忆可能是可遗传的假设，并帮助寄主植物的后代由于熟悉而选择有益的菌株，从而更好地理解非遗传遗传性，并为互惠关系的维持提供见解。该项目还为本科生提供资助的研究经验，这已被证明可以改善STEM的多样性并提高保留率。互惠关系的产生和维持呈现出一个进化难题，因为双方都希望按照自己的利益行事。就像所有的互惠关系一样，房东有被伴侣利用的风险，从而导致关系破裂。选择忠诚和有益的伙伴的能力可以稳定伙伴关系。然而，尽管有证据表明寄主植物能够优先与更有益的伴侣结瘤，但在豆科植物与根瘤菌的共生关系中，允许伴侣选择的机制尚未被揭示。该项目检验了被选中的伴侣可能通过遗传（寄主植物和根瘤菌基因）、表观遗传和环境因素的组合来确定的预测。研究小组将利用有胡须的三叶草（Trifolium barbigerum）来确定前几代的跨代效应是否会影响寄主植物对共生伴侣的选择。本项目将通过荧光标记、qPCR和元条形码的结合，在菌株水平上区分根瘤菌，量化根瘤菌占用率，以确定以前暴露于菌株及其效力是否影响寄主植物选择。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。