西瓜基因組框架圖繪制與果實品質基因挖掘

張海英 林魁 張明方 張建國 張永兵

摘 要：該研究在西瓜全基因組測序數據基礎上，進一步利用Solexa等新一代測序技術開展了具有典型生態類型的西瓜代表性種質資源的全基因組變異分析，完成了西瓜基因組序列精細圖譜構建、全基因組的基因功能注釋和大規模SNP位點挖掘。以該實驗室構建的西瓜97103 X PI296341-FR重組自交系群體，利用基于全基因組精細圖譜開發的SSR、InDel和SV標記，構建了西瓜高密度SSR遺傳圖譜。利用西瓜高密度SSR遺傳圖譜和標記scaffold定位結果，將234個scaffold錨定到染色體上，scaffold總長度330.4Mb，覆蓋了西瓜組裝基因組大小的93.5%。對該實驗室構建的97103細菌人工染色體（BAC）文庫進行末端測序，獲得了1664條長度約為800bp的BAC末端序列，對物理染色體進行FISH雜交分析，明確了人工染色體與物理染色體的對應關系。利用高抗枯萎病3個生理小種的西瓜材料PI296341-FR，完成了枯萎病生理小種race1誘導的根系SSH文庫測序分析，獲得了1 756條unigene，構建了枯萎病菌誘導的西瓜根系轉錄組表達圖譜等。利用全基因組測序構建的西瓜全基因組精細圖譜，通過序列比對，對影響果實糖分積累重要基因、影響果肉顏色形成的重要基因、西瓜根系對枯萎病生理小種race1的抗性相關的12個基因進行基因組精細定位，確定了這16基因在西瓜基因組上的精確位置，以及與之緊密連鎖的側翼標記。建立了國際西瓜功能基因組學數據庫（International Watermelon Genome Initiative，IWGI）。

關鍵詞：西瓜 基因組 果實 品質 基因

Abstract：Watermelon， Citrullus lanatus， is an important cucurbit crop grown throughout the world. Here we report a high-quality draft genome sequence of the east Asia watermelon cultivar 97103 （2n = 2× = 22） containing 23，440 predicted protein-coding genes. Comparative genomics analysis provided an evolutionary scenario for the origin of the 11 11 11 11 watermelon chromosomes derived from a 7-chromosome paleohexaploid eudicot ancestor. Resequencing of 20 watermelon accessions representing three different C. lanatus subspecies produced numerous haplotypes and identified the extent of genetic diversity and population structure of watermelon germplasm. Genomic regions that were preferentially selected during domestication were identified. Many disease-resistance genes were also found to be lost during domestication. In addition， integrative genomic and transcriptomic analyses yielded important insights into aspects of phloem-based vascular signaling in common between watermelon and cucumber and identified genes crucial to valuable fruit-quality traits， including sugar accumulation and citrulline metabolism.

Key Words：Watermelon；Genome；Fruit；Quality；Gene

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