Hyderabad, June 23 : A breakthrough study on plant symbioses, holds promise of higher pigeon pea yields in the country. Popularly known as 'Arhar', 'Toor' or 'Tuvar' in Indian households, pigeon pea serves as a primary protein source for millions of poor people in developing countries. However, the crop often suffers from inconsistent yields and poor nodule formation in India. Plant symbiosis with nitrogen-fixing soil bacteria or rhizobia, is key to sustainable agriculture. Pulses and other legumes develop complex symbiotic associations with rhizobia at root nodules-rhizobia 'fix' and supply nitrogen to the host plants; plants, in return, provide carbon and energy. A research team led by Prof Appa Rao Podile, faculty in the Department of Plant Sciences, University of Hyderabad (UoH), in a three-year collaboration with two groups in the United Kingdom - Prof Philip Poole's group at the Department of Plant Sciences, University of Oxford, and Dr Andrew Neal at Rothamsted Research - has made a major breakthrough in plant symbiosis studies, a UoH release stated. The UoH team comprising of three PhD scholars, Ch Danteswari, Anirban Basu, and PVSRN Sarma, assessed the microbial community associated with pigeon pea roots in different soil types with a comprehensive approach and found the root microbial composition was primarily determined by the plant developmental stage and soil type rather than the plant variety. The study concluded that the low nodulation efficiency of pigeon pea is due to the inadequate presence of appropriate symbionts in the soils. Indian soils were mainly found to harbor non-symbiotic Rhizobium spp, rather than symbiotic or nodule-forming Bradyrhizobium spp. These findings will pave the way for selecting and applying appropriate symbionts to improve pigeon pea yields and nodulation under Indian conditions. It suggests that the inoculant strain selection of symbionts for pigeon pea should be based not only on their nitrogen fixation potential but, more importantly, on their competitiveness in agricultural soils. The project was supported by the Department of Biotechnology (DBT), Government of India, and Biotechnology and Biological Sciences Research Council (BBSRC), UK. /IANS