Molecular Basis of Self-Incompatibility in Petunia

矮牵牛自交不亲和性的分子基础

• 批准号: 0235176
• 负责人: Teh-hui Kao
• 金额: $ 42万
• 依托单位: Pennsylvania State Univ University Park
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-04-01 至 2006-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0235176&HistoricalAwards=false
• 关键词: Molecular; Basis; Self; Incompatibility; Petunia

0235176Kao Most flowering plant species produce bisexual flowers with both male and female reproductive organs located in close proximity. A number of reproductive strategies have been adopted during the course of evolution to allow flowering plants to prevent inbreeding and promote out-crosses. One strategy is self-incompatibility (SI), which allows pistils of flowering plants to reject self-pollen and accept non-self pollen. Three families of flowering plants, Solanaceae, Rosaceae and Scrophulariaceae, all use an RNase-based SI mechanism. Here, the pistil S-RNase gene and the yet unidentified pollen S-gene located at a genetic locus, the S-locus, control the outcome of pollination. In any given species, there are many different S-haplotypes (i.e., variants) of the S-locus, with each S-haplotype carrying a specific allele of the S-RNase gene and the pollen S-gene. During pollen tube growth in a pistil, if the S-haplotype carried by the pollen tube matches one of the two S-haplotypes carried by the pistil, the growth will be inhibited and thus the pollen tube cannot deliver the sperm cell to the ovary for fertilization. It is thought that S-RNases produced in the pistil are taken up by pollen tubes, and that the RNase activity of S-RNases is responsible for growth inhibition of pollen tubes. Although all S-RNases can enter a pollen tube, only the self S-RNase (the S-RNase of the same S-haplotype as the pollen tube) is able to function inside the pollen tube. This raises a question as to how S-haplotype specific inhibition can be achieved. To address this question, the pollen S-gene must be identified. The PI's group has been using Petunia inflata, a wild relative of garden petunia, as a model to study S-RNase based SI, and has recently identified a very likely candidate, named PiSLF, for the pollen S-gene. It is located near the S-RNase gene, expressed in pollen, and shows allelic sequence differences, all of which are properties expected of the pollen S-gene. Moreover, a similar gene has been found to be located near the S-RNase gene of Antirrhinum hispanicum, a species in the Scrophulariaceae. PiSLF will be a major focus of this project. In vivo approaches will be used to confirm whether PiSLF is indeed the pollen S-gene. Most F-box proteins are components of SCF complexes that are involved in ubiquitin-mediated protein degradation. Thus, several in vitro approaches will be used to examine whether PiSLF mediates specific degradation of non-self S-RNases in the pollen tube. Another focus of the project will be on the completion of the cloning of a contiguous chromosome region (contig) of the S-locus. This contig will be used for identifying other S-locus linked genes and, in the event that PiSLF is found not to be the pollen S-gene, for identifying additional candidates. Accomplishment of this project will not only significantly advance understanding of the RNase-based self/non-self recognition mechanism, but also contribute to the understanding of selective protein degradation mediated by F-box proteins. The latter has recently emerged as an important regulatory mechanism for a variety of cellular and developmental processes in diverse organisms. On the practical side, if PiSLF is confirmed to be the pollen S-gene, one can explore the possibility of restoring the SI trait to self-compatible cultivated species by transferring the S-RNase gene and the PiSLF gene to facilitate hybrid seed production. If successful, this will have a very important agronomic impact. In the United States, the majority of crops are grown from hybrid seed, because such plants have greater vigor and produce higher yield than plants grown from seed obtained from self-pollination. Currently, hybrid seed production requires manual or mechanical removal of anthers from the plants serving as female parent to prevent self-fertilization. This is a very labor-intensive, costly, and inefficient process. Thus, there is a pressing need for more economically advantageous methods for hybrid seed production.

0235176KAO大多数开花的植物物种产生双性恋花朵，男性和女性生殖器官都靠近。 在进化过程中，已经采用了许多生殖策略，以允许开花植物防止近亲繁殖和促进交叉。 一种策略是自我兼容性（SI），它允许开花植物的雌蕊拒绝自花生并接受非自其花粉。 三个开花植物的家族，茄科，酒渣鼻科和卷心菜科，都使用基于RNase的SI机制。 在这里，雌蕊S-RNase基因和位于遗传基因座S-Ocus的尚未识别的粉s基因控制授粉的结果。 在任何给定的物种中，S-cocus都有许多不同的S-型型（即变体），每个S-型型均带有S-RNase基因的特定等位基因和花粉s基因。 在雌蕊的花粉管生长过程中，如果花粉管携带的S-型型与雌蕊携带的两种S-型型型匹配，则该生长将受到抑制，因此花粉管不能将精子细胞递送到卵巢上以进行受精。 据认为，在雌蕊中产生的S-RN酶是通过花粉管吸收的，并且S-RNase的RNase活性负责抑制花粉管的生长抑制。 尽管所有S-RNass都可以进入花粉管，但仅自s-RNase（与花粉管相同的S-型型的S-RNase）能够在花粉管内部起作用。 这就提出了一个问题，即如何实现S-Haplotype特定的抑制作用。 为了解决这个问题，必须确定花粉s基因。 PI的小组一直在使用petunia forta，这是花园矮牵牛的野生亲戚，作为研究基于S-RNase Si的模型，最近在花粉S-Gene中确定了一个名为Pislf的候选人。 它位于S-RNase基因附近，在花粉中表达，并显示等位基因序列差异，所有这些都是花粉s基因所期望的特性。 此外，已经发现类似的基因位于肌科中的一种物种抗rhinum西班牙裔的S-RNase基因附近。 PISLF将是该项目的主要重点。 体内方法将用于确认PISLF是否确实是花粉s基因。 大多数F-box蛋白是与泛素介导的蛋白质降解有关的SCF复合物的成分。 因此，将使用几种体外方法来检查PISLF是否介导花粉管中非自身S-RNase的特异性降解。 该项目的另一个重点将是完成S-Ocus连续染色体区域（重叠群）的克隆的完成。 该重叠群将用于识别其他S-Ocus链接基因，如果发现Pislf不是花粉S-Gene，则用于识别其他候选者。该项目的完成不仅将显着提高人们对基于RNase的自我/非自我识别机制的理解，而且还有助于理解F-box蛋白介导的选择性蛋白质降解。 后者最近成为多种生物体中各种细胞和发育过程的重要调节机制。 在实际方面，如果将PISLF确认为花粉s基因，则可以通过转移S-RNase基因和PISLF基因来促进杂交种子的产生，从而探索将Si性状恢复为自兼容培养物种的可能性。 如果成功，这将产生非常重要的农艺影响。 在美国，大多数农作物是由杂种种子生长的，因为这种植物具有更高的活力，并且产生的产量高于从自花生中获得的种子而生长的植物。 目前，杂种种子的产量需要手动或机械从作为女性父母的植物中的花药去除以防止自我施肥。 这是一个非常密集，昂贵且效率低下的过程。 因此，迫切需要更经济上有利的杂种种子生产方法。