Abstract：
Various bacterial species are associated with plant roots. However, symbiotic and free-living plant growth-promoting bacteria (PGPB) can only help plants to grow and develop under normal and stressful conditions. Several biochemical and in vitro assays were previously designed to differentiate between the PGPB and other plant-associated bacterial strains. This chapter describes and summarizes some of these assays and proposes a strategy to screen for PGPB. To determine the involvement of the PGPB in abiotic stress tolerance, assays for the ability to produce 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase, ammonium, gibberellic acid (GA), indole acetic acid (IAA), and microbial volatile organic compounds (mVOCs) are described in this chapter. Additionally, assays to show the capacity to solubilize micronutrients such as potassium, phosphorus, and zinc by bacteria were also summarized in this chapter. To determine the contribution of the PGPB in biotic stress tolerance in plants, Fe-siderophore, hydrogen cyanide, and antibiotic and antifungal metabolites production assays were described. Moreover, assays to investigate the growth-promotion activities of a bacterium strain on plants, using the gnotobiotic root elongation, in vitro, and pots assays, were explained. Finally, an assay for the localization of endophytic bacterium in plant tissues was also presented in this chapter. Although the assays described in this chapter can give evidence of the nature of the mechanism behind the PGPB actions, other unknown growth-promoting means are yet to decipher, and until then, new methodologies will be developed.
摘要：
各种细菌物种与植物根相关。然而,共生和自由生活的植物生长促进细菌（PGPB）只能帮助植物在正常和压力条件下生长和发育。先前设计了几种生化和体外测定以区分PGPB和其他植物相关细菌菌株。本章描述并总结了其中一些检测方法，并提出了筛选PGPB的策略。为了确定PGPB在非生物胁迫耐受性中的参与，测定产生1-氨基环丙烷-1-羧酸（ACC）脱氨酶的能力，铵，赤霉素（GA），吲哚乙酸(IAA),和微生物挥发性有机化合物(mVOCs)在本章中描述。此外,显示溶解微量营养素如钾的能力的测定法，磷，本章还对细菌产生的锌进行了总结。为了确定PGPB在植物的生物胁迫耐受性中的贡献，铁-铁载体，氰化氢,描述了抗生素和抗真菌代谢产物的产生试验。此外，研究细菌菌株对植物的生长促进活性的测定，利用生性根伸长，在体外，和罐化验，被解释了。最后,本章还介绍了植物组织中内生细菌的定位方法。尽管本章中描述的分析可以证明PGPB作用背后的机制的性质，其他未知的促进增长手段尚未破译，在那之前,将开发新的方法。
