García de Salamone I E, Hynes R K, Nelson L M
Department of Soil Science, University of Saskatchewan, Saskatoon, Canada.
Can J Microbiol. 2001 May;47(5):404-11. doi: 10.1139/w01-029.
One of the proposed mechanisms by which rhizobacteria enhance plant growth is through the production of plant growth regulators. Five plant growth promoting rhizobacterial (PGPR) strains produced the cytokinin dihydrozeatin riboside (DHZR) in pure culture. Cytokinin production by Pseudomonas fluorescens G20-18, a rifampicin-resistant mutant (RIF), and two TnphoA-derived mutants (CNT1, CNT2), with reduced capacity to synthesize cytokinins, was further characterized in pure culture using immunoassay and thin layer chromatography. G20-18 produced higher amounts of three cytokinins, isopentenyl adenosine (IPA), trans-zeatin ribose (ZR), and DHZR than the three mutants during stationary phase. IPA was the major metabolite produced, but the proportion of ZR and DHZR accumulated by CNT1 and CNT2 increased with time. No differences were observed between strain G20-18 and the mutants in the amounts of indole acetic acid synthesized, nor were gibberellins detected in supernatants of any of the strains. Addition of 10(-5) M adenine increased cytokinin production in 96- and 168-h cultures of strain G20-18 by approximately 67%. G20-18 and the mutants CNT1 and CNT2 may be useful for determination of the role of cytokinin production in plant growth promotion by PGPR.
根际细菌促进植物生长的一种推测机制是通过产生植物生长调节剂。五种促植物生长根际细菌（PGPR）菌株在纯培养中产生了细胞分裂素二氢玉米素核苷（DHZR）。利用免疫测定和薄层色谱法在纯培养中进一步表征了荧光假单胞菌G20 - 18（一种耐利福平突变体（RIF））以及两种合成细胞分裂素能力降低的TnphoA衍生突变体（CNT1、CNT2）产生细胞分裂素的情况。在稳定期，G20 - 18产生的三种细胞分裂素，即异戊烯基腺苷（IPA）、反式玉米素核糖（ZR）和DHZR的量高于这三种突变体。IPA是产生的主要代谢产物，但CNT1和CNT2积累的ZR和DHZR的比例随时间增加。在合成的吲哚乙酸量方面，未观察到G20 - 18菌株与突变体之间存在差异，并且在任何菌株的上清液中均未检测到赤霉素。添加10^(-5) M腺嘌呤使G20 - 18菌株在96小时和168小时培养物中的细胞分裂素产量增加了约67%。G20 - 18以及突变体CNT1和CNT2可能有助于确定细胞分裂素产生在PGPR促进植物生长中的作用。
