BACKGROUND Soybean red crown rot is a major soil-borne disease all over the world, which severely affects soybean production. Efficient and sustainable methods are strongly desired to control the soil-borne diseases. PRINCIPAL FINDINGS We firstly investigated the disease incidence and index of soybean red crown rot under different phosphorus (P) additions in field and found that the natural i...

Inoculation of legume seed is an efficient and convenient way of introducing effective rhizobia to soil and subsequently the rhizosphere of legumes. However, its full potential is yet to be realised. Following widespread crop failures, the manufacture of high quality inoculants revolutionised legume technology in Australia in the 1960s. Many improvements to inoculants and the advent of an inocu...

In legume-rhizobia symbiosis, the nodule number is controlled to ensure optimal growth of the host. In Lotus japonicus, the nodule number has been considered to be tightly regulated by host-derived phytohormones and glycopeptides. However, we have discovered a symbiont-derived phytohormonal regulation of nodule number in Mesorhizobium loti. In this study, we found that M. loti synthesized gibbe...

Fifty-seven strains of various Rhizobium species were analyzed by two-dimensional gel electrophoresis. Since the protein pattern on such gels is a reflection of the genetic background of the tested strains, similarities in pattern allowed us to estimate the relatedness between these strains. All group II rhizobia (slow growing) were closely related and were very distinct from group I rhizobia (...

bengal, asparagus agar (Allen, 1951), asparagus agar plus 1:80,000 crystal violet, and asparagus agar plus 1:15,000 rose bengal. The addition of dyes decreased the number of contaminants but also appeared to inhibit the development of the rhizobia. All plates were examined daily for 2 weeks. Smears of colonies which resembled rhizobia were examined. Pure cultures were obtained by the use of bot...

The gibberellin (GA) phytohormones are produced not only by plants but also by fungi and bacteria. Previous characterization of a cytochrome P450 (CYP)-rich GA biosynthetic operon found in many symbiotic, nitrogen-fixing rhizobia led to the elucidation of bacterial GA biosynthesis and implicated GA9 as the final product. However, GA9 does not exhibit hormonal/biological activity and presumably ...

Rhizobia are bacteria that can fi xate atmospheric nitrogen in association within the root or the stem nodules of legume plants and transform atmospheric nitrogen to ammonia. Soil environmental conditions are critical factors for the persistence and survival of rhizobia in the soil. Th e changes in the rhizosphere environment can aff ect both growth and saprophytic competence, which will infl u...

Kura clover (Trifolium ambiguum M.B.) is a persistent rhizomatous forage legume, whose use in the U.S.A. is limited by establishment difficulties in part attributable to nodulation problems. In this study, soil was collected from established stands of Kura clover growing in 9 diverse North American environments. Rhizobia were plant-trapped using Kura clover cv. Endura as host, then rhizobia fro...

Symbiotic rhizobia induce many changes in legumes that could affect aboveground interactions with herbivores. We explored how changing the intensity of Bradyrhizobium japonicum, as modulated by soil nitrogen (N) levels, influenced the interaction between soybean (Glycine max) and herbivores of different feeding guilds. When we employed a range of fertilizer applications to manipulate soil N, pl...

Indigenous rhizobia in soil present a competition barrier to the establishment of inoculant strains, possibly leading to inoculation failure. In this study, we used the natural diversity of rhizobial species and numbers in our fields to define, in quantitative terms, the relationship between indigenous rhizobial populations and inoculation response. Eight standardized inoculation trials were co...