White F F, Taylor B H, Huffman G A, Gordon M P, Nester E W
J Bacteriol. 1985 Oct;164(1):33-44. doi: 10.1128/jb.164.1.33-44.1985.
The T-DNA regions of the root-inducing (Ri) plasmid pRiA4b of Agrobacterium rhizogenes were characterized. Two regions, designated TL-DNA and TR-DNA, were found to be integrated and stably maintained in the plant genome. The TL-DNA spanned a 15- to 20-kilobase region of pRiA4b and was separated from the TR-DNA region by at least 15 kilobases of nonintegrated plasmid DNA. The TR-DNA region also spanned a 15- to 20-kilobase region of pRiA4b and included a region of homology to the tms morphogenic loci of the tumor-inducing (Ti) plasmid of Agrobacterium tumefaciens. Eighteen deletions and 95 transposon insertions were generated in the T-DNA regions and tested for alterations in virulence. Insertions into four loci in the TL-DNA affected the morphology of root formation of Kalanchoë diagremontiana leaves and stems, but had no visible effects on other host plants. Insertions into two loci (tms-1 and tms-2) in the TR-DNA eliminated virulence symptoms on all plants tested, with the exception of K. diagremontiana stems, where sparse root formation occurred. Complementation experiments with Ri and Ti plasmid T-DNA mutations indicate that the tms genes of the two plasmids serve similar functions and suggest a functional relationship between one or more genes of the TL-DNA and the cytokinin synthesis locus tmr of the Ti plasmid.
对发根农杆菌的根诱导型（Ri）质粒pRiA4b的T-DNA区域进行了表征。发现两个区域，即TL-DNA和TR-DNA，整合并稳定存在于植物基因组中。TL-DNA跨越pRiA4b的一个15至20千碱基区域，并与TR-DNA区域被至少15千碱基的非整合质粒DNA隔开。TR-DNA区域也跨越pRiA4b的一个15至20千碱基区域，并包含与根癌农杆菌的肿瘤诱导型（Ti）质粒的tms形态发生位点同源的区域。在T-DNA区域产生了18个缺失和95个转座子插入，并测试了毒力的改变。TL-DNA中四个位点的插入影响了落地生根叶片和茎的根形成形态，但对其他寄主植物没有明显影响。TR-DNA中两个位点（tms-1和tms-2）的插入消除了所有测试植物上的毒力症状，但落地生根茎除外，在那里形成了稀疏的根。用Ri和Ti质粒T-DNA突变体进行的互补实验表明，两种质粒的tms基因具有相似的功能，并暗示TL-DNA的一个或多个基因与Ti质粒的细胞分裂素合成位点tmr之间存在功能关系。
