Potential of Bradyrhizobia inoculation to promote peanut growth and beneficial Rhizobacteria abundance.

AIMS: To investigate the effects of three symbiotic Bradyrhizobium strains on peanut growth and on rhizobacterial communities in flowering and harvest stages in an organic farm, also to evaluate the role of plant development in influencing peanut rhizobacterial microbiota and correlations among the inoculants, rhizobacterial communities and plant growth. METHODS AND RESULTS: Peanut seeds were inoculated with three individual Bradyrhizobium strains, plant growth performance was measured in two developmental stages and rhizobacterial communities were analysed by Illumina sequencing of rpoB gene amplicons from peanut rhizosphere. The three bradyrhizobial inoculants significantly increased the nodule numbers and aboveground fresh weight of peanut plants regardless of the different growth stages, and the pod yields were increased to some extent and significantly positively correlated with Bradyrhizobium abundances in rhizosphere. Principal coordinate analysis indicated that the rhizobacterial communities were strongly influenced by the inoculation and peanut developmental stages. The bradyrhizobia inoculation increased relative abundances of potentially beneficial bacteria in peanut rhizosphere, and also altered rhizobacterial co-occurrence association networks and important network hub taxa. Similarly, plant development also significantly influenced the structure, composition and co-occurrence association networks of rhizobacterial communities. CONCLUSIONS: Bradyrhizobial inoculants increased peanut growth and yields, they and plant development affected the assembly of peanut rhizobacterial communities. SIGNIFICANCE AND IMPACT OF THE STUDY: Rhizobial inoculants improved the host plant performance that might also be associated with the dynamic changes in rhizobacterial community except enhancing the biological nitrogen fixation and helps to profoundly understand the mechanism how rhizobia inoculants improve plant growth and yields.

Rhizobial biogeography and inoculation application to soybean in four regions across China.

AIMS: The aim of the study was to survey rhizobial biogeography and to inoculate soybean with selected rhizobia in China to enhance symbiotic nitrogen fixation (SNF). METHODS AND RESULTS: Biogeography, genetic diversity and phylogeny of soybean rhizobia were surveyed. Inocula were prepared and applied to soybean. Results showed that Bradyrhizobium elkanii and Ensifer fredii were widely distributed in acid and alkaline soils respectively. Available iron was detected as the first determinant for distribution of the two rhizobia and the soybean varieties did not greatly affect the rhizobial compatibility. Geographical latitude and precipitation in June were the main geographical and climatic factors affecting the rhizobial distribution. Inoculation with selected rhizobia increased the nodule number, fresh weight, occupation ratio, seed protein content and soybean yields. CONCLUSIONS: Selection and application of effective soybean rhizobia across China according to biogeography were clarified to promote the SNF, thereby improving soybean yield. SIGNIFICANCE AND IMPACT OF THE STUDY: Rhizobial diversity and biogeography were evaluated systematically in six sites across China. Available iron and soil pH are found to be the most important determinants for the distribution of soybean rhizobia. Inoculation to soybean enhances SNF, positively correlating to the increase in soybean yield and seed protein content.

Common stress and serum cortisol and IL-12 levels in missed abortion.

To investigate stress levels, serum cortisol levels, and changes in IL-12 concentration in patients with missed abortion. Patients with missed abortion (n = 48) were age and gestational age-matched with normal early pregnancy cases (n = 48). All subjects completed a stress evaluation survey questionnaire about common stressors. Venous blood samples were collected at 07.00 hours, and serum cortisol and IL-12 concentrations were measured by electrochemiluminescence immunoassay and ELISA methods, respectively. Missed abortion patients demonstrated a significantly higher number of common stressors and higher serum cortisol levels compared to controls (both p < 0.05). Dilation and curettage did not lead to significant differences in serum cortisol and IL-12 levels (p > 0.05). Stress and immunity alterations of the immune system may contribute to the aetiology of missed abortion.