Metabolites and microbes of Tetrastigma: the ecology of host choice in Rafflesia and potential applications in ex situ conservation of the worlds largest flower

在东南亚日益减少的热带雨林中，莱佛士花罕见但巨大的恶臭栗色花朵引人注目，迷惑地引诱腐肉苍蝇，因此俗称“尸花”。与大多数植物不同，Rafflesia是一种专性植物寄生虫，没有茎、根和叶，也没有光合作用，而光合作用被认为是植物的特征。仅感染热带葡萄藤四分藤（tetrastigma），而且只感染少数品种，其原因尚不清楚。尽管莱佛士花是一种有魅力的保护标志，但没有西方植物园种植莱佛士花，因为它实际上仍然不知道如何种植。该项目旨在了解莱佛士虫选择宿主的生态学——与非宿主相比，四头柱头虫宿主中的哪些分子和微生物使它们对莱佛士虫感染敏感，以及如何利用这些基本信息指导繁殖。相反，该项目将产生代谢和微生物过程的数据增强宿主免疫功能，为什么某些物种不被Rafflesia寄生，以及如何将这些知识应用于葡萄，Tetrastigma的近亲，以抵抗寄生虫感染。此外，该项目将吸引代表性不足的学生，促进他们在生物多样性科学领域的职业发展，同时为菲律宾的土著社区提供能力建设，这些社区将收集样本。这种对基础科学的理解可能有一天会让莱佛士——植物界的熊猫——在植物园中盛开，促进教育和保护。时机至关重要，因为一旦灭绝，尸花就不能再复活了。Rafflesia （Rafflesiaceae, Malpighiales）是一种内生全寄生寄生虫，完全依赖于其寄主藤Tetrastigma （Vitaceae, Vitales）的营养，一生都生活在它的体内，只有在开花时才会出现。然而，并不是所有的tetrastizing物种都支持Rafflesia感染。该项目旨在通过代谢物分析和宏基因组分析，了解莱佛士虫选择宿主的生态学，重点研究受感染宿主物种特有的化学和微生物群。比较多个Rafflesia-Tetrastigma物种系统将澄清使某些Tetrastigma宿主与非宿主的共同模式，揭示不同Rafflesia在感染期间如何相似地改变宿主生态，以及破译物种系统之间的代谢和微生物特性，这可以解释Rafflesia的宿主选择。在农业中，嫁接的成功与否取决于接穗和砧木的亲缘关系，但属于不同目的的来佛花是如何成功逃避宿主免疫的，这些基本信息如何应用于防止作物嫁接不相容？如果寄生植物不同谱系的异养进化中存在相似的寄主降解代谢物，则所得数据还将揭示与其他寄主-寄生虫系统相比趋同进化的程度。这些数据将阐明宿主化学型和植物调节微生物内生菌，它们可能促进和维持Rafflesia感染，因此，Rafflesia园艺的移地保护，同时获得可能有益于其他农作物的见解。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。

Amidst the dwindling rainforests of Southeast Asia, Rafflesia’s rare but massive malodorous maroon flower stands out, deceptively luring carrion flies, hence the common name, “corpse flower”. Unlike most plants, Rafflesia is an obligate plant parasite, bereft of stems, roots, and leaves, and devoid of photosynthesis, which supposedly defines plants. Solely infecting the tropical grape vine Tetrastigma—and only a few species of it—it is unknown why. Despite being a charismatic icon of conservation, there is no western botanic garden that has grown Rafflesia because it is still virtually unknown how. This project aims to understand the ecology of Rafflesia’s host choice—what molecules and microbes in Tetrastigma hosts make them susceptible to Rafflesia infection compared to non-hosts, and how this basic information may be used to guide propagation. Conversely, this project will yield data on the metabolic and microbial processes underlying enhanced host immune function in Tetrastigma, why certain species are not parasitized by Rafflesia, and how this knowledge can be applied in grapes, Tetrastigma’s close relative, to resist parasitic infections. Moreover, the project will engage underrepresented students and catalyze their careers in biodiversity science, while providing capacity building to indigenous communities in the Philippines where samples will be collected. This understanding of the fundamental science may one day allow Rafflesia—the panda of the plant world—to be in full bloom in botanic gardens, fostering education and conservation. Timing is critical, because once extinct, the corpse flower can no longer be revived.Rafflesia (Rafflesiaceae, Malpighiales) is an endophytic holoparasite, completely dependent on its host vine Tetrastigma (Vitaceae, Vitales) for nutrition, living inside it throughout its life and only emerging to flower. However, not all Tetrastigma species support a Rafflesia infection. The project aims to understand the ecology of Rafflesia’s host choice, focusing on the chemistry and microbiota unique to infected host species through metabolite profiling and metagenomic analysis. Comparing multiple Rafflesia-Tetrastigma species systems will clarify common patterns that make certain Tetrastigma spp. hosts versus non-hosts, reveal how different Rafflesia spp. similarly alter host ecology during an infection, as well as decipher the metabolic and microbial idiosyncrasies between species systems that could explain Rafflesia’s host choice. In agriculture, grafting success is dependent on how closely related the scion and rootstock are, but how does Rafflesia, belonging to a different order from its host, successfully evade host immunity, and how can this basic information be applied in preventing graft incompatibility in crops? Resulting data will also reveal the extent of convergent evolution compared to other host-parasite systems, if there are similar host-degrading metabolites in the evolution of heterotrophy in disparate lineages of parasitic plants. These data will elucidate host chemotypes and plant-regulating microbial endophytes that could facilitate and sustain a Rafflesia infection, and consequently, Rafflesia horticulture for ex situ conservation while gaining insights that could potentially benefit other agricultural crops.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.