【作者】 阳义健；

【导师】 唐云明； 廖志华；

【作者基本信息】 西南大学 ， 生物化学与分子生物学， 2006， 硕士

【摘要】 甘薯(Ipomoea batatas(L．)Lam．)是我国四大主要粮食作物之一，总产量和种植面积均居世界首位。甘薯是一种以无性繁殖为主的植物，在种质资源搜集、保存过程中，存在一个品种由于名称不同，导致多个副本被收集、保存的情况。同时，我国育成的甘薯品种遗传基础狭窄，选育突破性的新品种相当困难，明确甘薯品种的遗传多样性是其品种改良的基础。由于其遗传背景复杂，采用传统方法对其品种难以准确鉴别，而DNA分子标记可以鉴定形态学上难以分辨的物种。通过建立甘薯的DNA指纹图谱，获得具有鉴别性的特征，在分子水平上鉴别种质资源。能作为传统鉴定方法的补充和发展，同时为寻找、保护和利用优良的种质资源提供分子水平的依据。本实验对13个品种的甘薯进行了ISSR分子标记及分析。 甘薯中含有以β-胡萝卜素为代表的多种类胡萝卜素，它们在体内能转换成维生素A或者视黄醇，其在淬灭自由基、增强人体免疫力、预防心血管疾病和防癌、抗癌方面的作用越来越引起人们的重视。类胡萝卜素前体的生物合成来源于经典的MVA途径和新近发现的MEP途径。为研究类胡萝卜素前体生物合成途径的分子生物学，本研究采用RACE方法从渝薯303中克隆了类胡萝卜素生物合成途径上一个重要基因的全长cDNA—IbIPI(isopentenyl diphosphate isomerase gene from Ipomoea batatas(L．)Lam．，甘薯异戊烯焦磷酸异构酶基因)，并对该基因及其编码的酶进行了生物信息学分析：在大肠杆菌中过量表达IbIPI推动了MEP途径代谢流向下游流动，促进类胡萝卜素的生物合成而验证了IbIPI的功能。对IbIPI基因的研究为深入阐明类胡萝卜素生物合成的分子生物学和生物化学机理奠定了基础，为利用甘薯进行类胡萝卜素的代谢工程提供了可能的调控靶点。 1 甘薯ISSR分子标记方法的建立 采用ISSR分子标记技术，对九州55、绵粉1号、澳墨红、壅菜种、广茨16、亚4、B50-285、恒进、渝紫263、台农10号、南薯88、台农69、川山紫等13个甘薯品种块根DNA进行了更多还原

【Abstract】 Sweetpotato , Ipomoea batatas (L.) Lam., ranks the forth staplest foodstuff crop in China, of which productivity and planting area are the first in the world. Because of its many biological complexities such as natural hereozygote and cross-incompatibility, the analysis of the genetic relationships among cultivars is of interest not only for germplasm conservation but for breeding purposes. Molecular techniques have been used widely for germplasm characterization, variety identification, phylogenetic study and diversity analysis. There have been very simple reports analyzing genetic relationships among sweetpotato cultivars with known origin using molecular markers. In the present study, genetic relationships among thirteen sweetpotato cultivars with known origin were analyzed using Inter-simple sequence repeat (ISSR) molecular markers.Sweetpotato provide both carbohydrate and important nutrients for human; among them, carotenoids, especially p-carotene are the most important nutrients in sweetpotato that is the precursor of vitamin A. In fact, sweetpotato is the main source that provides p-carotene for the people in the developing countries in Africa and Southeast Asia. The limiting contents of β-carotene in sweetpotato causes vitamin A deficiency related diseases such as xerophthalmia, corneal lesions, keratomalace and, in many instances, death. Carotenoids including p-carotene belong to the family of isoprenoids, which is synthesized from the general essential 5-carbon precursor isopentenyl diphosphate (IPP)and its isomer, dimethylallyl diphosphate (DMAPP). Isopentenyl diphosphate isomerase (IPI) is the enzyme that catalyzes the reversible conversion of IPP and DMAPP. In the present study, a new isopentenyl diphosphate isomerase gene from carotenoid-rich sweetpotato cultivars (namely YUSU303 developed ourselves) involved in the carotenoid precursor pathway was cloned, characterized and functionally expressed.1 Sweetpotato ISSR Molecular MarkersIn the present study, a method was established that could be employed to isolate high-quality更多还原