【作者】 沈庆庆；

【导师】 朱建华； 何新华； 彭宏祥；

【作者基本信息】 广西大学 ， 果树学， 2011， 硕士

【摘要】 广西是我国荔枝的主产区之一,拥有丰富的实生荔枝资源,尤其在桂西南地区分布的实生荔枝早熟性状明显。然而这些早熟荔枝实生资源被滥砍滥伐,数量逐渐减少,因此对桂西南早熟荔枝实生资源的调查研究刻不容缓。本研究通过开展实地调查、形态学分析、ISSR分子标记和核型分析对桂西南早熟荔枝实生资源进行遗传多样性研究,所获主要结果如下：1、在桂西南地区的龙州、大新、天等、靖西、德保、田东、田阳、大化、都安等县有早熟荔枝实生资源分布,且集中在人员活动比较频繁的地方。利用形态学鉴定69份实生单株,发现桂西南早熟荔枝实生资源遗传多样性丰富。该资源树龄较大,平均69.6年,树体高度在6.6m～20.5m之间；叶形有5种类型；花序较长,平均25.1cm；果实形状有8种类型,果实重量7.0g～29.2g,可溶性固形物含量在10.1%～18.2%之间,可食率在31.8%～69.0%之间。果肉不流汁、脆,但是风味大多偏酸。成熟期多在5月上中旬。2、对69份实生单株的形态学性状Q型系统聚类,在欧氏距离D=16.5处,69份资源分为3个类群。第一类群包含34份单株,为龟裂片锥尖状突起,裂片峰锐尖型；第二类群包含20份单株,为龟裂片锥尖状突起,裂片峰钝型；第三类群包含15份单株,为龟裂片乳头状突起,裂片峰锐尖型。3、69份实生单株果实性状模糊综合评判排在第1位的DB20为中果型,果皮颜色鲜红,肉质爽脆无涩味,清甜蜜香,有一定食用价值,但种子较大,可食率低,尚不能用于商业栽培。4、利用10条ISSR引物对83份早熟荔枝单株(品种)进行遗传多样性研究,结果表明：桂西南早熟荔枝实生资源具有较丰富的遗传多样性,采自不同地区的单株遗传差异性较大。5、利用ISSR标记对6个桂西南早熟实生荔枝居群进行了遗传多样性和遗传结构的研究,表明桂西南早熟实生荔枝的遗传分化同时受到群体内外的影响,并以群体内部分化为主。6、核型分析发现,染色体类型多数含m、sm、st、t,差异主要表现在不同类型染色体的数目以及它们在核型中排序位置的差异；染色体长度比值2.17-4.85,平均臂比值1.81～3.43,不对称系数值60.95%～68.36%,核型类型有2B、2C。7、利用形态学标记、ISSR分子标记、细胞学(染色体)标记3种方法检测桂西南早熟荔枝实生资源的遗传多样性水平,结果显示前两种方法检测到该资源的遗传多样性水平丰富,而细胞学(染色体)标记结果没有很好的体现遗传多样性水平丰富。更多还原

【Abstract】 Guangxi is one of the originating regions of litchi in china and has plenty of seeding litchi germplasm, especially early maturity characters are obvious in southwest Guangxi. However, these early mature seeding litchi resources are destroyed gradually, and the quantity is decreasing because of less protection and excessively hewing. It is very necessary to perform further study on early mature seeding litchi resource in southwest Guangxi. Based on this, field survey, morphological identification, ISSR analysis and karyotype analysis were applied to characterize the early mature seeding litchi resources and to assess their genetic diversity. The results were summarized as follows:1. The early mature seeding litchi resource mainly distributed in Longzhou, Daxin, Tiandeng, Jingxi, Debao, Tiandong, Tianyang, Dahua, Du’an, and centralized the place that people activity more frequently. The 69 seeding plants were morphological identified, and the results showed that the early mature seedling litchi resources of southwestern Guangxi were abundant genetic diversity. The average tree age was 69.6, height was 6.6m～20.5m; five types of leaf shape; long inflorescence, the average was 25.1cm; eight types of fruit shape, the weigh was 7.0g～29.2g, the soluble solid content was 10.1%～18.2%, the edible rate of the pulp was 31.8%～69.0%. The pulp was crisp, no flow juice, but the flavor was acid. They matured in early or middle of May.2. The 69 seeding plants were used to analyze based on Q-style cluster. At the Euclidean distance 16.5, the 69 seeding plants were divided into three groups. Group one included 34 seeding plants, which belonged to sharp-protruding tortoise-shaped lobe and sharp pointed tortoise-shaped lobe tip; Group two included 20 seeding plants, which belonged to sharp-protruding tortoise-shaped lobe and obtuse tortoise-shaped lobe tip; Group three included 15 seeding plants, which belonged to nipple-protruding tortoise-shaped lobe and sharp pointed tortoise-shaped lobe tip. 3. Fruit characteristics of 69 early mature litchi seedling plants were evaluated with Fuzzy comprehensive analysis methods. The NO.1 was DB20 that was middle-sized, bright red pericarp, crisp and no acerbity, sweet and honey fragrant. It had some edible value, but edible rate of the pulp was was low because of its big seed. So it couldn’t used to commercial cultivation.4. Ten pairs of ISSR primers were used to analyze 83 early litchi (variety) plants. The results showed that the early mature seeding litchi resource in southwest Guangxi had abundant genetic diversity, and there were hereditary difference among different areas.5. The genetic diversity and genetic structure about 6 wild populations of the early mature seeding litchi resources in southwest Guangxi were studied by ISSR markers. The genetic variation came from both inside and outside populations, and mainly from inside population.6. The results showed that the chromosome was composed of the m, sm, st and t chromosome by karyotype analysis. The diversity mainly display the number of different chromosome types and its site in the karyotype. The mean of ratio (longest/shortest), main ratio of arm, asymmetric coefficient value were 2.17～4.85,1.81～3.43,60.95%～68.36%. The karyotype were mainly indentified as symmetry type of 2B or 2C.7. Morphological identification, ISSR analysis and karyotype analysis were applied to assess their genetic diversity. The results of the first two methods showed that the early mature seedling litchi resource of southwestern Guangxi were abundant genetic diversity by before two kinds method, but karyotype analysis method was not.更多还原