PNAS：几千年前红薯通过农杆菌属感染获得转基因DNA

摘要 : 本期封面图片为各种各样物种的红薯,红薯是一种重要的粮食作物。


本期封面图片为各种各样物种的红薯,红薯是一种重要的粮食作物。

Tina Kyndt和她的团队，从来自世界各地的291个红薯样品中发现了土壤杆菌属细菌的基因组DNA序列。这些序列里面的编码基因只在红薯里面表达，一个序列被发现在所有的栽培甘薯样品都表达了，但在关系密切的野生植物没有表达。研究结果表明,红薯在几千年前可能通过农杆菌属感染获得转基因DNA,拥有这样特征的红薯在后面的自然驯化中就被选中了。

原文链接：

The genome of cultivated sweet potato containsAgrobacterium T-DNAs with expressed GENEs: An example of a naturally transgenic food crop

原文摘要：

Agrobacterium rhizogenes and Agrobacterium tumefaciens are plant pathogenic bacteria capable of transferring DNA fragments [transfer DNA (T-DNA)] bearing functional genes into the host plant genome. This naturally occurring mechanism has been adapted by plant biotechnologists to develop genetically modified crops that today are grown on more than 10% of the world’s arable land, although their use can result in considerable controversy. While assembling small interfering RNAs, or siRNAs, of sweet potato plants for metagenomic analysis, sequences homologous to T-DNA sequences from Agrobacterium spp. were discovered. Simple and quantitative PCR, Southern Blotting, genome walking, and bacterial artificial chromosome library screening and sequencing unambiguously demonstrated that two different T-DNA regions (IbT-DNA1 and IbT-DNA2) are present in the cultivated sweet potato (Ipomoea batatas [L.] Lam.) genome and that these foreign genes are expressed at detectable levels in different tissues of the sweet potato plant. IbT-DNA1 was found to contain four open reading frames (ORFs) homologous to the tryptophan-2-monooxygenase (iaaM), indole-3-acetamide hydrolase (iaaH), C-protein (C-prot), and agrocinopine synthase (Acs) genes of Agrobacterium spp. IbT-DNA1 was detected in all 291 cultigens examined, but not in close wild relatives. IbT-DNA2 contained at least five ORFs with significant homology to the ORF14, ORF17n, rooting locus (Rol)B/RolC, ORF13, and ORF18/ORF17n genes of A. rhizogenes. IbT-DNA2 was detected in 45 of 217 genotypes that included both cultivated and wild species. Our finding, that sweet potato is naturally transgenic while being a widely and traditionally consumed food crop, could affect the current consumer distrust of the safety of transgenic food crops.

doi: 10.1073/PNAS.1419685112

作者：生物帮

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