鸡品种鉴定DNA条形码序列筛选与验证

At present, the chicken germ plasm identification are mainly focus on morphology markers and production performance measurement, which is low accuracy and long time consuming. DNA barcoding is a new technique that uses a short DNA sequence from a standardized and greed-upon position in the genome as a molecular diagnostic for species-level identification, it is an effective complement for traditional taxonomy based on morphology. The research and application of DNA barcoding in poultry is in exploration stage, so the most important task is to select candidate genes or DNA regions and identify a suitable DNA barcode. The chicken is easily carried during human dispersal and migration, intensive interbreeding has occurred in the past, and hybridization between different breeds. Two or more gene should be incorporated into the core barcode for chicken.A three-marker combination of melanocortin 1-receptor、LEI0258 and Chromo helicase-DNA-Binding recommend as the chicken DNA barcode for the first time , to be supplemented with additional markers such as mtDNA D-loop base on earlier studies. To assess the effectiveness and universality of these barcode markers in chickens 30 chicken breeds（populations）including indigenous breeds key protected by country and import breeds will be used as materials. By ascertaining the breed specific sites and haplotypes in all brees, building the data bank of DNA barcoding of chicken breeds,in order to provide new method and thinking on germ plasm identification and true or false identification of breeds.

目前对鸡品种鉴定以形态学标记和生产性能测定为主，准确性低，耗时长。DNA条形码是指用短的、标准的DNA序列作为物种标记来鉴定物种的新技术,它是传统形态学分类的有效补充。鸡品种鉴定DNA条形码的研究和应用尚处于探索阶段，筛选候选片段、进而确定通用条形码是当前鸡品种鉴定条形码研究的首要任务。由于鸡的个体较小，随人类迁移被带到各地，发生了地方品种间的杂交。物种的边界由于杂交或者基因渗入而显得模糊不清，用单一片段来区分和鉴定十分困难，DNA 条形码片段组合方案或许更为可行。本项目在前期研究线粒体DNA 条形编码的基础上，以重点保护的地方鸡种以及商业化的肉鸡、蛋鸡30个品种（群体）为素材，用黑色素皮质激素受体-1（MC1R）基因、 LEI0258位点及染色体螺旋蛋白(CHD)基因作为DNA 条形码的编码候补序列，寻找品种独特的单倍型，构建鸡品种DNA 条形编码数据库，筛选适合鸡品种鉴定DNA条形码序列。

我国各地自然生态和经济文化的不同，形成了众多体型外貌和用途各异的鸡品种资源。本研究包括20个中国地方鸡品种和13个商业化配套系，利用线粒体D-loop区、MC1R基因、 微卫星LEI0258位点及CHD基因4个遗传标记大群体范围内探讨了中国地方鸡品种和商业化配套系的群体遗传结构。主要研究结果如下：线粒体D-loop区单倍型和鸡的经济性状密切相关，在快速型肉鸡和高产型蛋鸡中，E单倍型的比例占绝对优势。MC1R基因共发现12个多态位点，可以分为25个单倍型，没有发现MC1R基因突变位点与羽色的相关性，推断可能控制鸡羽色的位点位于MC1R基因的其他位置，或者有其他一个或者多个基因控制。LEI0258位点共检测到66个等位基因，长度范围为194-508 bp之间，其中194 bp、205 bp和361 bp为出现最多的3个等位基因，分别占10.9%、18.2%和6.9%。CHD基因相对较为保守，多态位点较少，共发现4个多态位点，可以分为A和B两种单倍型,由此推测中国地方品种可能有两个父系来源。通过本项目的研究，我们掌握了我国地方鸡品种和商业化配套系的线粒体DNA和核基因单倍型分布状况，对于我国鸡品种种质特性的开发和保护具有重要的理论和实践意义。