T4转基因番木瓜遗传性和果实品质分析

Analyses of virus resistance and fruit quality for T4 generation of transgenic papaya

对T4代转基因番木瓜进行了分子生物学和果实品质分析,结果表明,筛选获得的转基因番木瓜均为转番木瓜环斑病毒(PRV)复制酶突变体基因(RP),且对PRV抗性达到了高抗或免疫,RP基因在转基因植物中能稳定遗传至后代并在RNA水平上表达.在田间种植时,转基因木瓜的生长状况普遍好于普通番木瓜,尤其在生长后期(10月以后),普通番木瓜100%发病(大规模种植时),而大部分(约91.8%)转基因植株生长良好,果实较多且表面光洁、基本上无环斑.与非转基因亲本相比,T4代转基因番木瓜的果实长度增加2.6%～5%,果实直径变小0.6%～1.5%,果肉厚度增加了12%～15%,因而果实形状与亲本相近或更好,且信用价值更高.转基因番木瓜果实中水分、蛋白质、氮、脂肪、还原性糖、维生素A、维生素C和类胡萝卜素的含量与对照都无显著性差异,即转基因番木瓜与亲本具有实质等同性,这表明转入的外源基因对番木瓜果实品质没有不良影响.

Molecular biological characterization, fruit characters and nutrients were analyzed for T4 generation of transgenic papaya. All transgenic papaya plants with the mutated replicase （RP） gene from papaya ringspot virus （PRV） showed highly resistant or immune against PRV in field. The RP transgene can be steadily inherited to and expressed at RNA level in the progenies. The growth characteristics of transgenic papaya were much better than non-transgenic papaya in field. The nontransgenic papaya seedlings began to show typical symptoms of PRV after inoculated with PRV. They died quickly and never grew to produce fruit. The adult trees developed yellowed leaves and produced smaller fruits and doomed to a slow death after October. While most of transgenic papaya plants （about 91.8%） did not show any symptoms of PRV, and produced more, bigger and high quality fruits. Compared with non-transgenic plants, the fresh fruit length of T4 generation of transgenic papaya increased 2.6%-5%, and the diameter decreased 0.6%-1.5%. The flesh thickness of fresh fruit increased 12%- 15%, which made it fitter for eating. Although the fresh fruit quality had some change, we found there was no significant difference between transgenic and non transgenic. The quality characters of dry fruit including the contents of water, lipid, N, protein, reduced sugar, vitamin A, vitamin C and carotene in T4 generation of transgenic papaya were all the same as their non-transgenic parents. This means that transgenic plants and non-transgenic plants are substantial equivalent, and the transgene has no effect on dry fruit quality. In this study, we found vitamin A and vitamin C in red flesh papaya were 1.4-1.8 and 1.78-2.07 times more than the yellow flesh ones respectively, while N and protein were only 84.2%-92.1% and 82.1%-98.9% of the yellow flesh ones.