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

自交不亲和性允许开花植物的雌蕊拒绝自体花粉以防止近亲交配，并接受非自体花粉以促进异交。雌蕊如何区分自体和非自体花粉，以及雌蕊如何拒绝自体花粉，几十年来一直在进行深入的研究。矮牵牛是花园矮牵牛的野生近亲，将作为模型在一种类型的SI机制中解决这些问题。在这里，在雌蕊中表达的S核糖核酸酶基因和在花粉中表达的PiSLF基因决定了授粉的结果。本项目将利用分子遗传学和生物化学的方法研究PiSLF的生化特性，并确定PiSLF的一个等位变异如何与其自身和非自身的S核糖核酸酶发生不同的相互作用，从而导致自体花粉管的特异性生长抑制。这一结果将促进对SI机制以及其他生物系统中自我/非自我歧视机制的长期问题的理解。由于许多F-box蛋白参与调节蛋白质的降解，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。硅在杂交种子生产中具有潜在的商业应用，这是生产更高活力和更高产量的植物的重要农业实践。了解SI机制可以使将SI性状恢复到作物物种以促进杂交制种成为可能。如果能够做到这一点，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方面的培训，并提供设计和执行对他们未来研究生涯有价值的实验的经验。

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.