Characterization of the indole-3 acetic acid (IAA) biosynthetic pathway in an epiphytic strain of Erwinia herbicola and IAA production in vitro
Characterization of the indole-3 acetic acid (IAA) biosynthetic pathway in an epiphytic strain of Erwinia herbicola and IAA production in vitro
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DOI：
10.1139/m96-079
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发表时间：
1996-06-01
影响因子：
2.8
通讯作者：
Lindow, SE
中科院分区：
文献类型：
--
作者：
Brandl, M;Clark, EM;Lindow, SE
从吲哚-3-丙酮酸和吲哚-3-乙醛合成吲哚-3-乙酸(IAA)，而不是从吲哚-3-乙酰胺和其他IAA生物合成途径的中间体中合成吲哚-3-乙酸(IAA)。TLC、HPLC和CC-MS分析表明，菌株299R的培养上清液中含有吲哚-3-丙酮酸、吲哚-3-乙醇和IAA。酶法检测到吲哚-3-乙醛。此外，299R株基因组DNA与丁香假单胞菌的iaam和iaaH基因没有同源性。Savastanoi，即使在南方杂交中也是在低严格条件下进行的。这些观察结果有力地表明，与能够通过吲哚-3-乙酰胺合成IAA的胆汁形成细菌不同，吲哚-3-丙酮酸途径是该植物相关菌株合成IAA的主要途径。在氮素限制条件下，菌株299R在添加色氨酸的培养物中IAA的合成提高了10倍以上，这表明细菌附生植物在其自然栖息地生长过程中IAA的合成可能起到了作用。
An epiphytic strain of Erwinia herbicola (strain 299R) synthesized indole-3-acetic acid (IAA) from indole-3-pyruvic acid and indole-3-acetaldehyde, but not from indole-3-acetamide and other intermediates of various IAA biosynthetic pathways in enzyme assays. TLC, HPLC, and CC-MS analyses revealed the presence of indole-3-pyruvic acid, indole-3-ethanol, and IAA in culture supernatants of strain 299R. Indole-3-acetaldehyde was detected in enzyme assays. Furthermore, strain 299R genomic DNA shared no homology with the iaaM and iaaH genes from Pseudomonas syringae pv. savastanoi, even in Southern hybridizations performed under low-stringency conditions. These observations strongly suggest that unlike gall-forming bacteria which can synthesize IAA by indole-3-acetamide, the indole-3-pyruvic acid pathway is the primary route for IAA biosynthesis in this plant-associated strain. IAA synthesis in tryptophan-supplemented cultures of strain 299R was over 10-fold higher under nitrogen-limiting conditions, indicating a possible role for IAA production by bacterial epiphytes in the acquisition of nutrients during growth in their natural habitat.