Elite Bradyrhizobium strains boost biological nitrogen fixation and peanut yield in tropical drylands

Effect of arbuscular mycorrhiza and rhizobium on physiology and yield of peanut under drought conditions

Drought is the one primary issue limiting peanut growth and productivity. The study aimed to investigate the effects of arbuscular mycorrhizal fungi (AMF), rhizobium (Rhi), and their combinations on phenolic content, proline content, growth, and yield of peanut under different soil water regimes. The pot experiments were carried out for two growing seasons under greenhouse conditions and designed based on a 2×3 factorial in randomized complete block design (RCBD) with four replications. Factor A comprised two soil water regimes: field capacity (FC) and 1/3 available soil water (1/3 AW), whereas factor B included three different types of microorganisms: (i) uninoculated control, (ii) arbuscular mycorrhiza (AMF), and (iii) a combination of AMF and rhizobium (Rhi) inoculations. Data were collected for growth, proline content, phenolic content, yield, and yield components. Drought stress significantly reduced in relative water content, leaf area, biomass, yield, and yield components of peanut, whereas leaf phenolic content was increased under drought stress. Higher pod dry weight was achieved under FC conditions (28.87 g plant-1), and it was reduced to 16.06 g plant-1 under 1/3 FC. Interestingly, AMF+Rhi synergistically increased the leaf area compared with non-incubated peanut under 1/3 FC conditions. AMF-inoculated peanut tended to increase biomass, while the combination of AMF+Rhi tended to have higher yield components compared with uninoculated control, especially for the weight of 100 seeds.

Complete genome sequence of Bradyrhizobium sp. 62B, a native nitrogen-fixing rhizobium isolated from peanut nodules

We present the complete genome sequence of Bradyrhizobium sp. 62B, a strain isolated from the root nodules of peanut plants that grow in central Argentina. The genome consists of 8.15 Mbp, distributed into a chromosome of 7.29 Mbp and a plasmid of 0.86 Mbp.