Yang Suijuan, Zhang Xinghai, Cao Zhaoyun, Zhao Kaipeng, Wang Sai, Chen Mingxue, Hu Xiufang
College of Life Science, Zhejiang Sci-Tech University, Road 2, Hangzhou, China.
Microb Biotechnol. 2014 Nov;7(6):611-20. doi: 10.1111/1751-7915.12148. Epub 2014 Aug 20.
Growth-promoting Sphingomonas paucimobilis ZJSH1, associated with Dendrobium officinale, a traditional Chinese medicinal plant, was characterized. At 90 days post-inoculation, strain ZJSH1 significantly promoted the growth of D. officinale seedlings, with increases of stems by 8.6% and fresh weight by 7.5%. Interestingly, the polysaccharide content extracted from the inoculated seedlings was 0.6% higher than that of the control. Similar growth promotion was observed with the transplants inoculated with strain ZJSH1. The mechanism of growth promotion was attributed to a combination of phytohormones and nitrogen fixation. Strain ZJSH1 was found using the Kjeldahl method to have a nitrogen fixation activity of 1.15 mg l(-1) , which was confirmed by sequencing of the nifH gene. Using high-performance liquid chromatography-mass spectrometry, strain ZJSH1 was found to produce various phytohormones, including salicylic acid (SA), indole-3-acetic acid (IAA), Zeatin and abscisic acid (ABA). The growth curve showed that strain ZJSH1 grew well in the seedlings, especially in the roots. Accordingly, much higher contents of SA, ABA, IAA and c-ZR were detected in the inoculated seedlings, which may play roles as both phytohormones and 'Systemic Acquired Resistance' drivers. Nitrogen fixation and secretion of plant growth regulators (SA, IAA, Zeatin and ABA) endow S. paucimobilis ZJSH1 with growth-promoting properties, which provides a potential for application in the commercial growth of D. officinale.
对与传统中药材铁皮石斛相关的促生长少动鞘氨醇单胞菌ZJSH1进行了特性分析。接种90天后，ZJSH1菌株显著促进了铁皮石斛幼苗的生长，茎增加了8.6%，鲜重增加了7.5%。有趣的是，接种幼苗中提取的多糖含量比对照高0.6%。对接种ZJSH1菌株的移栽苗也观察到了类似的生长促进作用。生长促进机制归因于植物激素和固氮作用的结合。采用凯氏定氮法发现ZJSH1菌株的固氮活性为1.15 mg l(-1)，nifH基因测序证实了这一点。利用高效液相色谱-质谱联用技术，发现ZJSH1菌株能产生多种植物激素，包括水杨酸（SA）、吲哚-3-乙酸（IAA）、玉米素和脱落酸（ABA）。生长曲线表明，ZJSH1菌株在幼苗中生长良好，尤其是在根部。因此，在接种的幼苗中检测到SA、ABA、IAA和反式玉米素核苷（c-ZR）的含量要高得多，它们可能同时作为植物激素和“系统获得性抗性”驱动因子发挥作用。固氮和植物生长调节剂（SA、IAA、玉米素和ABA）的分泌赋予少动鞘氨醇单胞菌ZJSH1促生长特性，这为其在铁皮石斛商业种植中的应用提供了潜力。
