近日，我室林先贵研究员团队在PLoS ONE上发表了关于紫色光养细菌促进甜叶菊生长和糖分积累方面的研究。
植物促生细菌在农业增产中具有十分特殊的重要意义，可同时实现农业持续增产和环境安全。紫色光养细菌R. palustris J2作为植物促生细菌的一种，其作用已被多次证实，但是其复杂的作用机理还需要进一步挖掘。本研究选取经济糖类作物–甜叶菊为研究对象，甜叶菊叶片中含有多种低热量、高甜度的甜菊糖苷，糖尿病患者可食用。其中尤以甜叶菊苷（SteviosideST）为主要成分，ST还具有多种抗肿瘤活性，因此，目前市场需求量非常大。
本研究以不同施用方式为比较研究R. palustris J2在甜叶菊上的作用效果，结果发现：甜叶菊花蕾前期短时的喷施与根灌R. palustris J2都能够促进甜叶菊生长和ST的积累，且对于ST的影响喷施大于根灌。其中，根灌喷施联合施用对地上部生物量影响最显著，且与对照相比，ST单株产量提高了69.2％。根灌R. palustris J2提高了土壤脱氢酶活性，可能在根际通过激活土壤细菌的代谢活动促进了甜叶菊的生长；叶面喷施增加了老叶中叶绿素的含量，可能是通过影响叶际微生物的群落活性，或者分泌了植物生长激素促进了甜叶菊生物量的增加和ST的积累。该研究首次报道了R. palustris J2在甜叶菊上的促生增产效果，从而为R. palustris J2的农业应用提供理论依据，同时也为甜叶菊种植提供了安全、环保、有效的生物施肥途径。
. Purple Phototrophic Bacterium Enhances Stevioside Yield by Stevia rebaudiana Bertoni via Foliar Spray and Rhizosphere Irrigation. PLoS ONE 8(6): e67644. doi:10.1371-journal.pone.0067644
Abstract
This study was conducted to compare the effects of foliar spray and rhizosphere irrigation with purple phototrophic bacteria (PPB) on growth and stevioside (ST) yield of Stevia. rebaudiana. The S. rebaudiana plants were treated by foliar spray rhizosphere irrigation and spray plus irrigation with PPB for 10 days respectively. All treatments enhanced growth of S. rebaudiana and the foliar method was more efficient than irrigation. Spraying combined with irrigation increased the ST yield plant -1 by 69.2% as compared to the control. The soil dehydrogenase activity S. rebaudiana shoot biomass chlorophyll content in new leaves and soluble sugar in old leaves were affected significantly by S+I treatment too. The PPB probably works in the rhizosphere by activating the metabolic activity of soil bacteria and on leaves by excreting phytohormones or enhancing the activity of phyllosphere microorganisms.
