Agrobacterium Regulation of Plant Responses

农杆菌对植物的遗传转化是自然界中唯一记录的基因转移到真核生物的案例。因此，该系统已经引起了广泛的科学听众的关注，他们关注它的生物学，它在揭示植物遗传学复杂问题中的应用以及它在创造转基因植物中的生物技术应用。最近的发现扩大了农杆菌作为将DNA转移到真菌、卵菌和动物的载体的可能应用。通过dna - aflp分析，本实验室证实了农杆菌和大肠杆菌在培养中改变了鹰嘴豆细胞中植物防御和胁迫应答基因的表达。然而，农杆菌也诱导了一个编码结节样蛋白的基因，该基因未被大肠杆菌改变，这表明农杆菌可以诱导特异性宿主基因。该项目扩展了这些观察结果，并将使用高密度微阵列技术研究模式植物拟南芥细胞培养中的全局表达。拟南芥的细胞培养将与大肠杆菌以及在感染过程中不同主要步骤阻断的精通农杆菌和突变体共培养24小时。比较用微阵列表达的基因将揭示这些基因被农杆菌特异性改变。比较由转移熟练菌株和突变体引起的基因表达变化将开始确定导致这些变化的遗传因素。使用第一组突变体观察到的效果将通过使用在感染过程中单个步骤阻断的其他突变体进一步完善。这些实验的结果将提供对农杆菌独特的遗传因素的深入了解，农杆菌提供了克服宿主防御的能力，并最终导致DNA转移到范围广泛的植物和其他真核细胞中。

Genetic transformation of plants by Agrobacterium tumefaciens is the only documented case of gene transfer to eukaryotes in nature. As such, this system has attracted a great deal of attention from a broad scientific audience concerned with its biology, its use in unraveling complex problems in plant genetics and its biotechnological applications in creating transgenic plants. Recent findings have broadened the possible applications of Agrobacterium as a vector for the transfer of DNA to fungi, oomycetes and animals. Using cDNA-AFLP analysis, our laboratory demonstrated that Agrobacterium and E.coli alter the expression of plant defense and stress response genes of Ageratum conyzoides cells in culture. However, Agrobacterium also induced a gene encoding a nodulin-like protein which was not altered by E.coli suggesting that Agrobacterium can induce specific host genes. The project expands on these observations and will study global expression in cell cultures of the model plant Arabidopsis thaliana using high density microarray technology. Cell cultures of Arabidopsis will be cocultivated for 24 hours with E.coli as well as transfer proficient Agrobacterium and mutants blocked at different major steps in the infection process. Comparing the genes expressed using microarrays will reveal these genes that are specifically altered by Agrobacterium. Comparing the alterations in gene expression induced by the transfer proficient strain with the mutants will begin to identify genetic factors responsible for these alterations. The effects observed using the first set of mutants will be further refined by using additional mutants blocked at single steps in the infection process. The results of these experiments should provide insight into the unique genetic factors of the near symbiont Agrobacterium which provides its ability to overcome host defenses and ultimately lead to the transfer of DNA to a remarkably wide range of plants and other eukaryotic cells.