植物的自花受精會造成自交退化,，即自交所產(chǎn)后代適應(yīng)性降低,。但正如達(dá)爾文所預(yù)測的，當(dāng)授粉者或交配對象稀少時(shí),，自交可能會受到青睞,。
防止自交的主要機(jī)制是自交不親和性識別體系，它由雄性和雌性特異性基因及修飾基因組成,。
據(jù)預(yù)測,，由花粉和種子傳播的雄性基因的突變相對于雌性基因的突變體會居支配地位。這個(gè)預(yù)測被對從歐洲各地獲得的以自交為主的擬南芥的DNA序列所做比較證實(shí),。在95%的這些序列中,，在雄性特異性基因(SCR)或一個(gè)衍生物中有一個(gè)破壞性的213-堿基對倒位。自交不親和性通過將這種重新排列恢復(fù)到其原始取向而得以恢復(fù),。(生物谷Bioon.com)
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生物谷推薦原文出處：
Nature doi:10.1038/nature08927
Evolution of self-compatibility in Arabidopsis by a mutation in the male specificity gene
Takashi Tsuchimatsu,Keita Suwabe,Rie Shimizu-Inatsugi,Sachiyo Isokawa,Pavlos Pavlidis,Thomas St?dler,Go Suzuki,Seiji Takayama,Masao Watanabe& Kentaro K. Shimizu
Ever since Darwin’s pioneering research, the evolution of self-fertilisation (selfing) has been regarded as one of the most prevalent evolutionary transitions in flowering plants1, 2. A major mechanism to prevent selfing is the self-incompatibility (SI) recognition system, which consists of male and female specificity genes at the S-locus and SI modifier genes2, 3, 4. Under conditions that favour selfing, mutations disabling the male recognition component are predicted to enjoy a relative advantage over those disabling the female component, because male mutations would increase through both pollen and seeds whereas female mutations would increase only through seeds5, 6. Despite many studies on the genetic basis of loss of SI in the predominantly selfing plant Arabidopsis thaliana7, 8, 9, 10, 11, 12, 13, 14, 15, it remains unknown whether selfing arose through mutations in the female specificity gene (S-receptor kinase, SRK), male specificity gene (S-locus cysteine-rich protein, SCR; also known as S-locus protein 11, SP11) or modifier genes, and whether any of them rose to high frequency across large geographic regions. Here we report that a disruptive 213-base-pair (bp) inversion in the SCR gene (or its derivative haplotypes with deletions encompassing the entire SCR-A and a large portion of SRK-A) is found in 95% of European accessions, which contrasts with the genome-wide pattern of polymorphism in European A. thaliana16, 17. Importantly, interspecific crossings using Arabidopsis halleri as a pollen donor reveal that some A. thaliana accessions, including Wei-1, retain the female SI reaction, suggesting that all female components including SRK are still functional. Moreover, when the 213-bp inversion in SCR was inverted and expressed in transgenic Wei-1 plants, the functional SCR restored the SI reaction. The inversion within SCR is the first mutation disrupting SI shown to be nearly fixed in geographically wide samples, and its prevalence is consistent with theoretical predictions regarding the evolutionary advantage of mutations in male components.
