The Role of the S-Locus F-Box Gene in S-RNase-Based Self-Incompatibility

自交不亲和使开花植物雌蕊拒绝自交花粉以防止近亲繁殖，而接受非自交花粉以促进异交。几十年来，人们对雌蕊如何区分自交花粉和非自交花粉以及雌蕊如何排斥自交花粉进行了深入的研究。膨胀矮牵牛，花园矮牵牛的野生亲戚，将作为一个模型来解决这些问题，在一种类型的SI机制。在这里，雌蕊中表达的S-RNase基因和花粉中表达的PiSLF （P. inflata S-locus F-box）基因决定了授粉的结果。本项目将采用分子遗传学和生化方法研究PiSLF的生化特性，并确定PiSLF的一个等位基因变体如何与其自身和非自身S-RNases发生不同的相互作用，从而导致对自身花粉管的特异性生长抑制。这一结果将有助于理解长期存在的关于SI机制的问题，以及其他生物系统中的自我/非自我歧视机制。由于许多F-box蛋白参与介导蛋白质降解，这项工作也将有助于理解F-box蛋白参与的其他生物的细胞和发育过程。SI在杂交制种方面具有潜在的商业应用潜力，杂交制种是生产更高活力和更高产量植物的重要农业实践。了解SI机制可以使SI性状恢复到作物物种中，以促进杂交种子生产。如果能做到这一点，将会产生巨大的农艺效益。该项目将完全由研究生和本科生进行，为他们提供植物生殖生物学的培训和实验设计和执行的经验，这将对他们未来的研究生涯有价值。

Self-incompatibility (SI) allows pistils of flowering plants to reject self-pollen to prevent inbreeding, and to accept non-self pollen to promote outcrossing. How the pistil distinguishes between self- and non-self pollen, and how the pistil rejects self-pollen have been under intensive investigation for many decades. Petunia inflata, a wild relative of garden petunia, will be used as a model to address these questions in one type of the SI mechanism. Here, the S-RNase gene expressed in the pistil, and the PiSLF (P. inflata S-locus F-box) gene expressed in the pollen determine the outcome of pollination. In this project, molecular genetic and biochemical approaches will be used to study the biochemical properties of PiSLF, and to determine how one allelic variant of PiSLF interacts differently with its self and non-self S-RNases to result in specific growth inhibition of self-pollen tubes. The results will advance understanding of the long-standing questions about the mechanism of SI, as well as of self/non-self discrimination mechanisms in other biological systems. Since many F-box proteins are involved in mediating protein degradation, this work will also contribute to understanding cellular and developmental processes in other organisms in which F-box proteins are involved. SI has potential commercial applications in hybrid seed production, an important agricultural practice for producing plants of higher vigor and higher yield. Understanding the SI mechanism could make it feasible to restore the SI trait back to crop species to facilitate hybrid seed production. If this can be accomplished, it will have tremendous agronomic benefits. This project will be entirely carried out by graduate and undergraduate students, providing them training in plant reproductive biology and experience in the design and execution of experiments that will be valuable for their future research careers.