水稻骨干親本遺傳效應的基礎研究

顧紅雅　湯述翥　李雙成　陳浩東　梁婉琪

摘 要：水稻骨干親本黃華占性狀優(yōu)良，育種譜系清晰，被選作該課題的主要研究對象之一。利用水稻的高通量測序結果，設計了一款超過5萬位點的高密度SNP芯片，對黃華占譜系中的部分水稻品種進行了高通量基因分型，以發(fā)掘受到了人工選擇的基因或位點；同時將此信息與重要農藝性狀進行基于單倍體型的關聯(lián)分析，鑒定到了幾十個性狀相關位點。比較桂朝2號、青六矮、豐矮占1號等高產品種和黃華占的穗型差異，發(fā)現(xiàn)這些品種的一次枝梗數(shù)目差異不大，而二次枝梗的數(shù)目有顯著差異，說明二次枝梗數(shù)目可能是造成這些品種最終穗粒數(shù)差異的主要原因；通過比較分析發(fā)現(xiàn)，桂朝2號和黃華占中CKX2、Ghd7、DEP2以及IPA/SPL14等重要穗型控制基因的序列是一致的，而其他一些品種則發(fā)現(xiàn)有基因序列多態(tài)性存在。鑒定了矮仔占→桂朝2號→黃華占為主線的秈稻骨干親本中sd1基因的等位性變異，發(fā)現(xiàn)5種變異類型；明確了桂朝2號及其衍生品種的均是利用低腳烏尖一類的sd1-d，而非矮仔占所帶有的sd1；利用染色體片段代換系比較了骨干親本揚稻6號（9311）sd1等位變異類型在秈、粳背景下的遺傳效應。蜀恢527是由四川農業(yè)大學水稻研究所于2000年選育成功的強優(yōu)勢恢復系，具有一般配合力高、所配組合多、雜種優(yōu)勢強、千粒重較大等優(yōu)點，被認為是雜交水稻的“第三代”代表恢復系。該研究廣泛收集了527系譜親本材料和目前在生產上廣泛應用的衍生恢復系約30份，利用高密度水稻SNP芯片進行全基因組掃描確定骨干親本基因組組成及區(qū)段確切來源；構建了527極其親本和衍生材料的基因組高密度單倍型圖譜，確定了骨干親本527的關鍵基因組區(qū)域，初步檢測了可能的重要農藝性狀關聯(lián)位點，為進一步確定關鍵基因組區(qū)段的重要控制（候選）基因、解析骨干親本527的分子基礎和遺傳效應奠定了基礎。同時，利用圖位克隆方法，克隆了水稻結實率控制關鍵基因PTB1，證實了PTB1基因是控制水稻花粉管生長、調控水稻結實率的關鍵基因，首次解析了水稻結實率這一重要產量性狀的分子機制，為進一步理解水稻花粉管生長和明確水稻結實率的相關調控通路提供了全新視點，并可能促進其在水稻高產穩(wěn)產中的直接應用。同時，通過該基因在527系譜的分析，從結實率角度闡述了527及其衍生材料表現(xiàn)高結實率的分子基礎。

關鍵詞：黃華占 蜀恢527 骨干親本 半矮稈基因 等位性變異 關鍵基因組區(qū)域 PTB1基因

Abstract：The backbone variety Huanhuazhan has many excellent agronomic traits， and most importantly is its clear breeding lineage. Therefore， Huanhuazhan and its derivatives have been selected as one of the key materials in this study. Based on the high-through put re-sequencing of rice genomes， a SNP chip with more than 50000 dots was designed. This chip was used for a high-through put genome-typing on the key rice varieties in Huanhuazhan lineage with the purpose of discovering genes or loci under human selection during rice cultivation. The association analysis of important agronomic traits and SNPs was performed， several dozen of associated loci were identified. Comparison of the panicle morphology of Huanghuazhan and its derivative varieties such as Guichao 2， Qingliuai， Fengaizhan 1 found that they had similar primary branching numbers， but different secondary branching numbers. It implies that the secondary branching number could be the major factor for the difference in final grain number/plant among the varieties. Gene sequence comparison found that some genes involving panicle morphology such as CKX2、Ghd7、DEP and IPA/SPL14 are quite similar in Huanghuazhan and Guichao 2， but different among other varieties. Analysis on the allelic variation of sd1 in the Aizizhan – Guichao 2 – Huanghuazhan lineage was performed， and five variation types were found among them. The gene sd1-d in Guichao 2 and its derivatives were from Deo-geo-woo-gen， not from Aizizhan （sd1）. The genetic effect of sd1 from 9311 （Yangdao 6） in both indica and japonica genomic background was tested using chromosomal segment substitution lines. Shuhui 527 was a very successful recover line， and it has been widely used a breeding material for its strong heterosis and heavy thousand-grain weight. More than 30 recover lines and other Shuhui 527 derivative varieties or lines were used for a genomic scanning to identify the fragments inherited from Shuhui 527. A high density hap-map of Shuhui 527 and its parental and derivative lines was constructed， and some key backbone fragments were identified. GWAS analysis found several sites which was associated with the most important yield-related traits. A key gene controlling seed-set， PTB1， was cloned using map-based cloning method. This gene is involved in controlling pollen tube. The variation pattern of PTB1 in Shuhui 527 and its parental and derivative lines provided a molecular basis for the high seed-set of Shuhui 527 and its derivatives.

Key Words：Huanghuazhan； Shuhui 527； Backbone varieties； Semi-dwarf gene； Allelic variation； Key genomic region； PTB1

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