Plant-assisted selection: a promising alternative for in vivo identification of wheat (Triticum turgidum L. subsp. Durum) growth promoting bacteria

Abstract

Background and aims: In this work we present the development of an easy and feasible in vivo alternative to identify promising Plant Growth Promoting Bacteria (PGPB), using wheat -as a model plant- growing under variable soil and climate conditions. Methods: The identification of promising strains was carried out by Plant-Assistant Selection (PAS) (compared with the conventional PGPB selection, named in this work as Metabolic Traits Selection or MTS). We validated the ability of the obtained strains by PAS to promote wheat growth, by analyzing biometric and nutrimental parameters, as well as the relative expressions of NRT1.4, GluTR, and 6-SFT1 genes. Results: Twenty strains were obtained by PAS (170 bacterial strains were originally co-inoculated to plants), of which, twelve strains showed the ability to promote wheat growth mainly by the stem development and the number of leaves. Moreover, thirteen strains up-regulated the 6-SFT1 gene, and three strains up-regulated the GluTR gen. Thus, the strains Enterobacter cloacae TS3, Microbacterium foliorum TS9, Bacillus cereus TS10, Paenibacillus lautus TE8, and Paenibacillus lautus TE10 were identified as promising PGPB, showing strong wheat growth promotion events compared with those strains obtained by MTS. Conclusions: PAS is an easy and feasible alternative for identification of PGPB. However, ecological and economic factors need to be investigated to use the obtained strains by PAS for commercial microbial inoculants formulations.