Dicarboxylate Transporters ofAzospirillum brasilenseSp7 Play an Important Role in the Colonization of Finger Millet (Eleusine coracana) Roots

Abstract

Azospirillum brasilense is a plant growth–promoting bacterium that colonizes the roots of a large number of plants, including C3 and C4 grasses. Malate has been used as a preferred source of carbon for the enrichment and isolation Azospirillum spp., but the genes involved in their transport and utilization are not yet characterized. In this study, we investigated the role of the two types of dicarboxylate transporters (DctP and DctA) of A. brasilense in their ability to colonize and promote growth of the roots of a C4 grass. We found that DctP protein was distinctly upregulated in A. brasilense grown with malate as sole carbon source. Inactivation of dctP in A. brasilense led to a drastic reduction in its ability to grow on dicarboxylates and form cell aggregates. Inactivation of dctA, however, showed a marginal reduction in growth and flocculation. The growth and nitrogen fixation of a dctP and dctA double mutant of A. brasilense were severely compromised. We have shown here that DctPQM and DctA transporters play a major and a minor role in the transport of C4-dicarboxylates in A. brasilense, respectively. Studies on inoculation of the seedlings of a C4 grass, Eleusine corcana, with A. brasilense and its dicarboxylate transport mutants revealed that dicarboxylate transporters are required by A. brasilense for an efficient colonization of plant roots and their growth.

Radiocarbon Dates from the Archaeological Site of Sakas, Bihar, India

“…Sakas is an archaeological site in Sasaram (Rohtas) district of Bihar in the foothills of Vindhyan-Kaimurranges, India (24°54'27"N; 83°58'3"E) (see Figure 1) (Singh et al 2020a(Singh et al , 2020b(Singh et al , 2020c(Singh et al , 2020d. In 2019 was excavated by Banaras Hindu University (Director of excavation Dr Vikas Kumar Singh) (Singh et al 2020a(Singh et al , 2020b(Singh et al , 2020c(Singh et al , 2020d. It is being analyzed by a collaborative team from Banaras Hindu University (PI: Prof. Vikas Kumar Singh, Prof. RN Singh) and Seoul National University (PI: Prof. Jennifer Bates).…”

“…During the 2019 excavation the earliest form of ceramics and lithics found look to similar to those found at nearby Senuwar, and as such the earliest period was determined to be of the Early Farming period. Singh et al (2020aSingh et al ( , 2020bSingh et al ( , 2020cSingh et al ( , 2020d suggested that the latest phase of the site was Chalcolithic based also on ceramics. In order to test how the relative chronology links to absolute dates samples were sent for radiocarbon dating.…”