【作者】 闻小霞；

【导师】 于喜艳；

【作者基本信息】 山东农业大学 ， 蔬菜学， 2010， 硕士

【摘要】 甜瓜(Cucumis melon L.)是世界性的重要园艺作物,糖分组成及含量是衡量甜瓜品质的主要依据之一。蔗糖、葡萄糖和果糖是甜瓜果实中主要的可溶性糖,其含量和组成对果实品质起重要作用,它们的含量和组成严格受蔗糖代谢酶调控,而蔗糖代谢酶包括蔗糖合成酶(SS)、蔗糖磷酸合成酶(SPS)和转化酶(Invertase),其中SS在蔗糖代谢中调控可逆反应,主要是起分解作用。SS活性的降低是蔗糖积累的前提条件,改变SS的活性能改变蔗糖的代谢模式。因此,利用现代分子生物学的方法改变蔗糖合成酶的活性对甜瓜品质育种具有重要的意义。本研究首先通过RT-PCR及3′、5′RACE技术克隆到了甜瓜果实蔗糖合成酶基因全长cDNA,研究了该基因在组织器官和果实发育过程中的表达特异性,然后构建了甜瓜果实SS基因的反义表达载体。以甜瓜自交系M01-3为材料,通过子房注射法将甜瓜果实反义SS基因进行了甜瓜遗传转化,目前已经收获转基因种子;同时用农杆菌介导法转化甜瓜,经PCR检测已经检测出5株转基因植株。研究的主要结果如下:1.通过RT-PCR及3′、5′RACE技术克隆到了甜瓜SS基因全长cDNA。测序结果表明该基因全长为2585bp,编码804个氨基酸,命名为CmSS1。2. Real-Time PCR结果表明:CmSS1在甜瓜根、茎、叶、雄花、雌花和成熟果实中均有表达。其中在根中的表达量最高,在果实中的表达量最低;在甜瓜果实发育不同时期中,随着果实发育时间的延长,CmSS1的表达量逐渐降低,在花后5 d时表达量最高,花后30 d表达量最低。3.将克隆在pMD18-T载体上的甜瓜CmSS1基因用BamHI和SalI酶切,酶切产物经0.1%琼脂糖凝胶电泳后回收1.4 kb的片段,将该片段与经相同的酶切后的植物表达载体pBI121进行连接,这样获得的重组质粒片段为反向插入35S启动子之后,TNOS终止子之前。经酶切和PCR检测表明,成功构建了甜瓜反义CmSS1基因的植物表达载体。4.利用子房注射法将反义CmSS1基因进行了甜瓜的遗传转化,现在已经收获种子大约1500粒,正在鉴定中。5.利用农杆菌介导法将反义CmSS1基因进行了甜瓜的遗传转化,经PCR检测,初步鉴定出5株转基因植株。更多还原

【Abstract】 Muskmelon (Cucumis melon L.) is one of the major horticultural crops. The content and composition of soluble sugars in fruit play key roles in muskmelon quality. Sucrose, glucose and fructose are the main soluble sugars。In melon fruit, the accumulation and composition of the soluble sugars in melon fruit are controlled by sucrose metabolism enzymes including sucrose synthase (SS), sucrose phosphate synthase (SPS) and acid invertase (AI). The previous studies showed that the SS played a key role in sucrose metabolism in muskmelon fruit. Therefore, cloning and characterization of SS encoding gene from muskmelon is necessary to toward the genetic improvement of the quality of muskmelon fruit.In this study, we cloned the SS full-length cDNA from muskmelon fruit by RT-PCR and 3’, 5’ RACE and this clone was named CmSS1. The expression levels of CmSS1 in the tissue-organ and during fruit development in muskmelon were analyzed by Real-time RT-PCR. We constructed the antisense expression vector of CmSS1 and transformed it to muskmelon by ovary injection method and Agrobacterium-mediated method . Five transgenic plants were obtained by PCR screening. The main results are as follows:1. The full-length cDNA of SS gene from muskmelon fruit were cloned by RT-PCR and 3′, 5′RACE. The sequence analysis showed that SS gene contained 2585 bp and coded 804 amino acid residues.2. Real Time PCR analysis indicated that CmSS1 transcripts are easily detected in the leaves, stems, mature fruit, roots and flowers. The highest expression level existed in root, However, in mature fruit showed the lowest level. With the development of fruit, the expression level of CmSS1 showed a decreased trendy. CmSS1 mRNA strongly expressed in 5 DAP fruit, the lowest level existed in 30 DAP fruit.3. A 1.4 Kb fragment of the CmSS1 was removed from pMD18-T vector by BamHⅠand SalⅠdigested and the fragment was ligated into the plant expression vector pBI121 in the antisense orientation. We constructed the antisense expression vector of CmSS1 successfully by PCR and digested with restricted enzymes.4. Anti-CmSS1 was transformed to muskmelon by ovary injection, at present we got the injected seeds.5. Anti-CmSS1 was transformed to muskmelon by Agrabactria-mediated and five transgenic plants were obtained by PCR screening.更多还原