西瓜基因组框架图绘制与果实品质基因挖掘

The Draft Genome of Watermelon

该研究在西瓜全基因组测序数据基础上,进一步利用Solexa等新一代测序技术开展了具有典型生态类型的西瓜代表性种质资源的全基因组变异分析,完成了西瓜基因组序列精细图谱构建、全基因组的基因功能注释和大规模SNP位点挖掘。以该实验室构建的西瓜97103 X PI296341-FR重组自交系群体,利用基于全基因组精细图谱开发的SSR、In Del和SV标记,构建了西瓜高密度SSR遗传图谱。利用西瓜高密度SSR遗传图谱和标记scaffold定位结果,将234个scaffold锚定到染色体上,scaffold总长度330.4Mb,覆盖了西瓜组装基因组大小的93.5%。对该实验室构建的97103细菌人工染色体（BAC）文库进行末端测序,获得了1664条长度约为800bp的BAC末端序列,对物理染色体进行FISH杂交分析,明确了人工染色体与物理染色体的对应关系。利用高抗枯萎病3个生理小种的西瓜材料PI296341-FR,完成了枯萎病生理小种race1诱导的根系SSH文库测序分析,获得了1 756条unigene,构建了枯萎病菌诱导的西瓜根系转录组表达图谱等。利用全基因组测序构建的西瓜全基因组精细图谱,通过序列比对,对影响果实糖分积累重要基因、影响果肉颜色形成的重要基因、西瓜根系对枯萎病生理小种race1的抗性相关的12个基因进行基因组精细定位,确定了这16基因在西瓜基因组上的精确位置,以及与之紧密连锁的侧翼标记。建立了国际西瓜功能基因组学数据库（International Watermelon Genome Initiative,IWGI）。

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. lanatussubspecies 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.