SPECIFIC OLIGOSACCHARIDE FORM OF THE RHIZOBIUM-MELILOTI EXOPOLYSACCHARIDE PROMOTES NODULE INVASION IN ALFALFA
SPECIFIC OLIGOSACCHARIDE FORM OF THE RHIZOBIUM-MELILOTI EXOPOLYSACCHARIDE PROMOTES NODULE INVASION IN ALFALFA
复制标题
DOI：
10.1073/pnas.89.12.5625
复制
发表时间：
1992-06-15
影响因子：
11.1
通讯作者：
LEIGH, JA
中科院分区：
文献类型：
--
作者：
BATTISTI, L;LARA, JC;LEIGH, JA
苜蓿根瘤菌菌株SU 47产生高分子量（HMW）和低分子量（LMW）形式的酸性外多糖琥珀聚糖。遗传学研究表明，琥珀多糖是苜蓿根瘤入侵所必需的。我们发现，低分子量琥珀聚糖，当施加外源苜蓿根，恢复根瘤入侵exoA，exoB，exoF，和exoH突变体。由于来自R.苜蓿属植物的LMff D1D2D3和LMff A突变体和来自木犀草素诱导的野生型培养物的LMff琥珀聚糖引起与来自未诱导的野生型菌株的LMff琥珀聚糖类似的作用。相反，来自exoA突变体的LMW组分、非琥珀酰化的LMW琥珀聚糖和HMW琥珀聚糖不促进侵袭，来自R.豆科植物根瘤菌、三叶草根瘤菌和根瘤菌菌株NGR 234。低分子量琥珀聚糖可以通过阴离子交换色谱分离成几个不同的亚组分，不同的重复亚基的多样性（单体，三聚体，四聚体）和电荷。当单独测试时，只有电荷最多的四聚体形式是活性的。这些结果表明，琥珀聚糖的特定低聚糖形式促进了苜蓿中的结节入侵。琥珀聚糖的作用模式的影响进行了讨论。
Rhizobium meliloti strain SU47 produces both high molecular weight (HMW) and low molecular weight (LMW) forms of an acidic exopolysaccharide, succinoglycan. Genetic studies have shown that succinoglycan is required for alfalfa root nodule invasion. We found that LMW succinoglycan, when applied exogenously to alfalfa roots, restored nodule invasion to exoA, exoB, exoF, and exoH mutants. Nodule initiation signals were not involved, since LMW succinoglycan from R. meliloti nodD1D2D3 and nodA mutants and from luteolin-induced wild-type cultures elicited effects similar to LMW succinoglycan from the uninduced wild-type strain. In contrast, LMW fractions from an exoA mutant, nonsuccinylated LMW succinoglycan, and HMW succinoglycan did not promote invasion, nor did LMW exopolysaccharides from R. leguminosarum by, trifolii and Rhizobium sp. strain NGR234. LMW succinoglycan could be separated by anion-exchange chromatography into several distinct subfractions differing in repeating subunit multiplicities (monomer, trimer, and tetramer) and charge. When tested singly, only the most charged, tetrameric form was active. These results show that a specific oligosaccharide form of succinoglycan promotes nodule invasion in alfalfa. The implications for the mode of action of succinoglycan are discussed.