EAGER: Self-incompatibility in elderberry

在地球上大约352，000种开花植物中，大约有一半具有有利于异花授粉的机制。 这种繁殖策略对于产生和维持植物生存和适应所需的遗传多样性至关重要。 人类直接依赖植物多样性来改良作物，间接依赖植物多样性来支持生态系统。 许多植物已经进化出识别和排斥自体花粉和近亲花粉的方法。 这些所谓的“自交不亲和系统”是防止自花授粉和促进异花授粉的最常见和最有效的机制之一。 迄今为止，控制自交不亲和性的基因，称为S基因，仅在少数植物家族中的三个系统中被确定。 该项目将确定接骨木中的S基因，接骨木是一种新兴的特种作物，富含抗氧化剂，用于葡萄酒，补充剂和其他产品。 候选基因的确定使用一种新的方法，优先考虑DNA序列差异，可能涉及花粉识别以及表达数据。 实验将通过测试特定S基因的存在或不存在是否可靠地预测哪些类型的花粉被接受或拒绝来评估这些候选基因。 其他实验将鉴定其他S基因变体。 用于确定接骨木S-基因的方法可以应用于其他自交不亲和系统，因此，进一步有助于理解植物多样性的维持。自交不亲和系统是植物控制交配的重要遗传机制之一。 通常，控制SI的基因S-基因具有许多等位基因变体，并且基本上，SI允许植物拒绝来自具有相似等位基因的潜在配偶的花粉。 SI种是专性异交种，因为自花花粉总是具有与雌蕊相同的S等位基因。 尽管S基因对植物多样性、进化和适应性具有极其重要的意义，但它们只在少数SI系统中被发现。 在这里，总体目标是阐明一个新的SI系统，确定控制S-基因，并促进其在科学和农业社区的使用。 我们表征了接骨木（Sambucus canadensis）中的SI，并使用RNASeq来鉴定候选S基因。 遗传实验将确定这些候选S基因是否真正控制接骨木SI。 将对分离不同S等位基因候选者的四个群体进行基因分型并测试授粉以确定它们是否拒绝来自携带相同等位基因的植物的花粉。 接骨木果是一种新兴的特色作物，具有潜在的健康益处，将在接骨木果和相关植物中鉴定出额外的S等位基因，以支持接骨木果改良社区。 具体而言，该项目将允许育种者和生产者预测商业品种的杂交行为。 与接骨木生产和改良有关的项目活动将通过演讲、视频和推广出版物广泛传播。 该项目还将通过提供实验室和实地植物科学的本科生研究培训，为人力资源开发做出贡献。该奖项反映了NSF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。

Roughly half of the approximately 352,000 species of flowering plants on earth possess mechanisms that favor cross-pollination. This reproductive strategy is crucial for generating and sustaining the genetic diversity that plants need to survive and adapt. Humans rely on plant diversity both directly, for crop improvement, and indirectly, for ecosystem support. Many plants have evolved ways to recognize and reject self-pollen and pollen from close relatives. These so-called “self-incompatibility systems” are among the most common and effective mechanisms that prevent self-pollination and favor cross-pollination. To date, the genes controlling self-incompatibility, called S-genes, have been identified in only three systems that operate in a handful of plant families. This project will identify S-genes in elderberry, an emerging specialty crop rich in antioxidants that is used in wine, supplements, and other products. Candidate genes were identified using a novel approach prioritizing DNA sequence differences that could relate to pollen recognition as well as expression data. Experiments will evaluate these candidate genes by testing whether the presence or absence of particular S-genes reliably predicts what types of pollen are accepted or rejected. Other experiments will identify additional S-gene variants. The approach used to identify elderberry S-genes may be applied to additional self-incompatibility systems and, thus, further contribute to understanding maintenance of plant diversity. Self-incompatibility (SI) systems are among the most important genetic mechanisms plants use to control mating. Typically, the genes controlling SI, S-genes, have numerous allelic variants, and, basically, SI allows plants to reject pollen from potential mates with similar alleles. SI species are obligate outcrossers because self-pollen always has the same S-alleles as the pistil. Notwithstanding their outsized importance for plant diversity, evolution and adaptability, S-genes have only been identified in a handful of SI systems. Here, the overall goals are to elucidate a new SI system, identify the controlling S-genes, and facilitate their use in the scientific and agriculture communities. We characterized SI in elderberry (Sambucus canadensis) and used RNASeq to identify candidate S-genes. Genetic experiments will ascertain whether these candidate S-genes truly control SI in elderberry. Four populations segregating for distinct S-allele candidates will be genotyped and test pollinated to determine whether they reject pollen from plants bearing the same alleles. Elderberry is an emerging specialty crop valued for potential health benefits, and additional S-alleles will be identified in elderberry and related plants to support the elderberry improvement community. Specifically, the project will allow breeders and producers to predict the crossing behavior of commercial varieties. Project activities related to elderberry production and improvement will be broadly disseminated via presentations, video, and Extension publications. The project also will contribute to human resource development by providing undergraduate research training in both laboratory- and field-based plant science.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.