RESUMEN
Plant growth-promoting rhizobacterial (PGPR) strains R62 and R81 have previously been isolated and characterized as part of the Indo-Swiss Collaboration in Biotechnology. Here we present the draft genome sequences of these two PGPR strains, with the aim of unraveling the mechanisms behind their ability to promote wheat growth.
Asunto(s)
ADN Bacteriano/química , ADN Bacteriano/genética , Genoma Bacteriano , Pseudomonas/genética , Datos de Secuencia Molecular , Reguladores del Crecimiento de las Plantas/metabolismo , Pseudomonas/aislamiento & purificación , Pseudomonas/metabolismo , Rizosfera , Análisis de Secuencia de ADN , Microbiología del Suelo , Triticum/crecimiento & desarrollo , Triticum/microbiologíaRESUMEN
Arbuscular mycorrhizal fungal (AMF) spore communities were surveyed in a long-term field fertilization experiment in Switzerland, where different amounts of phosphorus (P) were applied to soil. Plots receiving no P as well as plots systematically fertilized in excess to plant needs for 31 years were used to test the hypothesis that application of P fertilizer changes the composition and diversity of AMF communities. AMF spores were isolated from the field soil, identified, and counted so as to quantify the effect of P fertilization on AMF spore density, composition, and diversity. Trap cultures were established from field soil with four host plants (sunflower, leek, maize, and Crotalaria grahamiana), and the spore communities were then analyzed in substrate samples from the pots. Altogether, nine AMF species were detected in the soil. No evidence has been acquired for effect of P fertilization on spore density, composition, and diversity of AMF in both the field soil and in trap cultures. On the other hand, we observed strong effect of crop plant species on spore densities in the soil, the values being lowest under rapeseed and highest under Phacelia tanacetifolia covercrop. The identity of plant species in trap pots also significantly affected composition and diversity of associated AMF communities, probably due to preferential establishment of symbiosis between certain plant and AMF species. AMF spore communities under mycorrhizal host plants (wheat and Phacelia in the fields and four host plant species in trap pots) were dominated by a single AMF species, Glomus intraradices. This resulted in exceptionally low AMF spore diversity that seems to be linked to high clay content of the soil.