Optimisation of transgene action at the post-transcriptional level: high quality parthenocarpic fruits in industrial tomatoes.
Optimisation of transgene action at the post-transcriptional level: high quality parthenocarpic fruits in industrial tomatoes.
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DOI：
10.1186/1472-6750-2-1
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发表时间：
2002
影响因子：
3.5
通讯作者：
Spena A
中科院分区：
文献类型：
--
作者：
Pandolfini T;Rotino GL;Camerini S;Defez R;Spena A
单性结实的基因工程赋予园艺植物在降低果实产量和质量的环境条件下产生果实的能力。DefH 9-iaaM转基因，其预测的作用是在胎座、胚珠和衍生组织中特异性地赋予生长素合成，已经显示赋予几种植物物种（烟草、茄子、番茄）和品种单性结实。UC 82番茄植物是加工业使用的典型栽培品种，其DefH 9-iaaM基因转基因产生畸形的单性结实果实。对于DefH 9-RI-iaaM转基因的UC 82植物产生高质量的单性结实果实，DefH 9-RI-iaaM是一种DefH 9-iaaM衍生基因，其在其5 ′ ULR中通过用源自rolA内含子序列的87个核苷酸长的序列替换紧邻AUG起始密码子上游的53个核苷酸而被修饰。在体外翻译系统中，在其5 'ULR中修饰的iaaM mRNA的翻译效率比原始转录物低3-4倍。与DefH 9-iaaM花蕾相比，单性结实的最佳表达率与DefH 9-RI-iaaM花蕾中降低的转基因mRNA稳态水平相关。与iaaM基因的已知功能一致，DefH 9-RI-iaaM基因转基因的花蕾含有比对照未转化花蕾多10倍的IAA，但比DefH 9-iaaM花蕾少5倍。通过使用在转录后水平下调的生长素生物合成转基因，在不适合原始转基因的遗传背景中实现了单性结实的最佳表达率。因此，所述方法允许在转基因植物中产生所需性状的更宽范围的表达性。
Genetic engineering of parthenocarpy confers to horticultural plants the ability to produce fruits under environmental conditions that curtail fruit productivity and quality. The DefH9-iaaM transgene, whose predicted action is to confer auxin synthesis specifically in the placenta, ovules and derived tissues, has been shown to confer parthenocarpy to several plant species (tobacco, eggplant, tomato) and varieties. UC82 tomato plants, a typical cultivar used by the processing industry, transgenic for the DefH9-iaaM gene produce parthenocarpic fruits that are malformed. UC82 plants transgenic for the DefH9-RI-iaaM, a DefH9-iaaM derivative gene modified in its 5'ULR by replacing 53 nucleotides immediately upstream of the AUG initiation codon with an 87 nucleotides-long sequence derived from the rolA intron sequence, produce parthenocarpic fruits of high quality. In an in vitro translation system, the iaaM mRNA, modified in its 5'ULR is translated 3–4 times less efficiently than the original transcript. An optimal expressivity of parthenocarpy correlates with a reduced transgene mRNA steady state level in DefH9-RI-iaaM flower buds in comparison to DefH9-iaaM flower buds. Consistent with the known function of the iaaM gene, flower buds transgenic for the DefH9-RI-iaaM gene contain ten times more IAA than control untransformed flower buds, but five times less than DefH9-iaaM flower buds. By using an auxin biosynthesis transgene downregulated at the post-transcriptional level, an optimal expressivity of parthenocarpy has been achieved in a genetic background not suitable for the original transgene. Thus, the method allows the generation of a wider range of expressivity of the desired trait in transgenic plants.