Orgambide G, Philip-Hollingsworth S, Cargill L, Dazzo F
Department of Microbiology, Michigan State University, East Lansing 48824.
Mol Plant Microbe Interact. 1992 Nov-Dec;5(6):484-8. doi: 10.1094/mpmi-5-484.
1H-NMR spectroscopy showed that the extracellular heterpolysaccharides (EPS) from derivatives of Rhizobium leguminosarum bv. trifolii ANU843 altered in pSym nod composition or function (transposon insertions, deletion of pSym, induction by flavone, and introduction of cloned pSym nod regions from ANU843 and R. l. bv. viciae 248 on recombinant plasmids into the pSym-cured background of ANU843) differed only in 3-hydroxybutyrate stoichiometry per octaglycosyl unit. This change in EPS was likely to be an indirect effect of altered growth during expression of pSym nod genes in the presence of the flavone. No modifications were found in EPS made by R. l. bv. phaseoli 8002 when its resident pSym was deleted or replaced with pSym from R. l. bv. viciae 248, or with a derivative of this pSym lacking the host-specific nodulation genes nodFELMNTO. Thus, although certain O-acyl noncarbohydrate substitutions in EPS are affected by pSym nod genes (including the ones that determine host range) in certain backgrounds of R. leguminosarum, this change does not occur universally among all strains of R. leguminosarum. We conclude that the structure of the acidic EPS does not control host-specific nodulation of white clover, hairy vetch, and beans for the strains of R. leguminosarum tested here.
1H-核磁共振光谱显示，来自豌豆根瘤菌三叶草生物变种ANU843衍生物的细胞外杂多糖（EPS）在共生质粒结瘤组成或功能上发生改变（转座子插入、共生质粒缺失、黄酮诱导以及将来自ANU843和豌豆根瘤菌蚕豆生物变种248的克隆共生质粒结瘤区域通过重组质粒导入ANU843的共生质粒缺失背景中），仅在每个八糖基单元的3-羟基丁酸化学计量上有所不同。EPS的这种变化可能是在黄酮存在下共生质粒结瘤基因表达期间生长改变的间接效应。当菜豆根瘤菌8002的常驻共生质粒被缺失或被蚕豆根瘤菌248的共生质粒或缺乏宿主特异性结瘤基因nodFELMNTO的该共生质粒衍生物替代时，未发现其产生的EPS有修饰。因此，尽管在豌豆根瘤菌的某些背景下，EPS中的某些O-酰基非碳水化合物取代受共生质粒结瘤基因（包括决定宿主范围的基因）影响，但这种变化并非在所有豌豆根瘤菌菌株中普遍发生。我们得出结论，对于此处测试的豌豆根瘤菌菌株，酸性EPS的结构并不控制白三叶草、毛苕子和菜豆的宿主特异性结瘤。
