柑橘高密度遗传图谱构建与单条染色体识别研究

For the important fruits of citrus, up to now, chromosome recognition is very difficult. The previous genetic linakge map are mostly based on distantly related materials for parents (such as the reality constructed by the hybridization groups of Poncirus trifoliate is one of the parents) . Because sweet orange acts important role on the fresh food use and the processing, sweet orange was used as researchful materials in this project. First, the high density genetic linakge map was constructed with SSR, SCoT and SNP molecular markers using F1 population of about 200 progenies from sweet orange (Osb.)x tangor(Citrus unshiu (Mark.) Marc. x Citrus sinensis (L.) Osb.). At the same time, the high quality genome BAC library of the sweet orange would be built. Then base on the linakge map, screening special molecular markers located on different positions of 9 linake group would be carried out. Next, positive BAC clones containing special markers woule be obtained by PCR-based screening BAC Library. Finally, BAC-FISH technique would be used for BAC clones containing specific marker loci mapped to different linkage groups. So single chromosome of sweet orange would be recognized by the special BAC clone. Citrus high density genetic map to establish and a full set of sweet orange chromosome identification studies of the project should have particularly valuable for standardization of karyotype of citrus plants, single chromosome sorting, Gene mapping, genetic and physical map of the consolidation, and QTL location , molecular assisted breeding in the future.

针对重要果树柑橘至今染色体识别困难以及以往的遗传图谱大多是以关系较远的材料为亲本（如以枳为亲本之一）的杂交群体构建的现实，本课题选用在鲜食和加工中具重要地位的甜橙为材料，首先以甜橙与橘橙正反交材料约200株为作图群体，利用SSR、SNP和SCoT等几种分子标记构建高密度分子遗传图谱；同时，以甜橙为材料构建其基因组BAC文库；然后依据高密度图谱，筛选分布于甜橙9个连锁群不同位置的含上述标记的唯一位点，再利用PCR筛选BAC文库，获得含此标记的阳性BAC克隆，最后运用BAC-FISH技术将含特异标记位点的BAC克隆分别定位到不同连锁群上，以达到可以从甜橙基因组中分别识别单条染色体的目的。本课题建立的柑橘高密度遗传图谱及进行的全套甜橙染色体识别研究，对于今后柑橘类植物核型标准化、单条染色体分拣、基因定位、遗传图谱与物理图谱的整合、重要性状的QTL定位及辅助柑橘分子育种等均有重要参考意义。

柑橘是世界第一大水果，也是中国最重要的果树之一。柑橘品种的改良受到珠心胚干扰、童期长、树体大和遗传背景复杂等限制。构建高密度的遗传图谱有利于提高柑橘的育种效率，可以从分子水平对多基因控制的重要农艺性状和抗性基因进行遗传分析，为柑橘分子标记辅助育种奠定基础。本项目构建的f分子遗传图谱不同于以往柑橘属与近缘属杂交群体的图谱，主要在于作图群体为柑橘属的甜橙与橘橙的正反杂交群体，二者均为可以直接栽培使用的品种，由此群体构建的图谱更有助于重要农艺性状的定位，对辅助遗传育种具有重要的价值。同时进行的柑橘单条染色体的识别技术是利用从单倍体克里迈丁基因组序列里筛选的串联重复序列然后通过FISH技术将其定位到其体细胞染色体上，基本达到识别全套染色体。因此本项目构建的柑橘高密度遗传图谱及进行的柑橘单条染色体识别研究，对于今后柑橘类植物核型标准化、单条染色体分拣、遗传图谱与物理图谱的整合、重要性状的QTL定位及辅助柑橘分子育种等均有重要参考意义。