細胞質在玉米配子和合子生活力選擇中的作用研究報告

徐辰武

摘 要：偏分離是指觀察到的基因型比例偏離預期的孟德爾頻率的分離方式，被逐漸認為是一種重要的進化動力，偏分離的主要原因是由生存力位點造成的配子和合子的生存力差異。然而，母體細胞質也可能參與配子和受精卵的生存力選擇。該文的目的是定位玉米中的偏分離位點（SDL）并檢驗配子和合子的生存力是否與母體細胞質環境相關。在該研究中，以正反交構建的F2代分離群體為材料，構建了126個微衛星標記的遺傳連鎖圖，并利用全基因組掃描檢測不同母體細胞下分離群體的SDL，在供試的F2群體中共檢測到14個顯著的SDL。有趣的是，筆者發現在兩個不同母體胞質背景下，SDL中的基因型頻率發生了明顯變化，這表明在不同的細胞質環境下，配子和合子的的生存力發生了變化。此外，JB細胞質背景下，大多數檢測到的SDL和偏分離標記均偏向Y53，結果表明細胞質通過影響配子和合子的生存力選擇，在F2代群體的偏分離模式中起了重要的作用。

關鍵詞：偏分離 細胞質 選擇 生活力 玉米

The Maternal Cytoplasmic Environment May Be Involved in the Viability Selection of Gametes and Zygotes

Xu Chenwu

（Yangzhou University）

Abstract：Segregation distortion is the phenomenon whereby the observed genotypic frequencies of a locus fall outside the expectedMendelian segregation ratio， and it is increasingly recognised as a potentially powerful evolutionary force. The main reason forsegregation distortion is a difference in the viability of gametes and zygotes caused by viability loci in the segregating progeny.However， the maternal cytoplasm may also be involved in the viability selection of gametes and zygotes. The objectives of thisstudy were to map the segregation distortion loci （SDL） in maize and to test the hypothesis that the viability of gametes andzygotes may also be associated with the maternal cytoplasmic environment. In the present study， a reciprocal mating designwas conducted to generate an F2-segregating population. A linkage map was constructed with 126 microsatellite markers. A whole-genome scan was performed to detect the SDL in segregating populations with different maternal cytoplasm environments.Altogether， 14 SDL with strong LOD （logarithm （base 10） of odds） supports were identified in the specifically designed F2populations. Interestingly， we found dramatic changes in the genotypic frequencies of the SDL in the two maternal cytoplasmicbackgrounds， which indicated a change in the viability of gametes and zygotes in different cytoplasmic environments. Furthermore， in the JB cytoplasmic background， most of the detected SDL and complete distortion markers exhibited similar bias patternsfavouring the Y53 alleles. These results suggested that selfish cytoplasmic elements may have an important role in shaping thepatterns of segregation distortion in F2 populations through selective viability of gametes and zygotes.

Key Words： Segregation distortion； Eytoplasm； selection； Viability； Maize

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