Rhizobium leguminosarum bv. phaseoli 4292 Genome sequencing and assembly. Rhizobium leguminosarum bv. phaseoli 4292

Root Nodulating Bacteria (RNB) are soil inhabiting bacteria that form symbioses with legumes after infection of root hairs. The ‘GEBA-RNB’ initiative at the JGI aims to sequence 100 RNB strains isolated from various locations around the world. This project will support the systematic sequence-based studies and understanding of the biogeographical effects on species evolution as well as the mechanisms of symbiotic nitrogen fixation (SNF) by RNB. The latter is a significant asset for world agricultural productivity, farming economy and environmental sustainability. SNF reduces energy consumption required to produce nitrogenous fertilizer, saving $US 6.8 billion per year. SNF significantly reduces greenhouse gas emissions compared to intensive agriculture practice using artificial N-input. SNF benefits the environment (reduces dry-land salinity, increases soil fertility, and prevents waterway eutrophication). Root endosymbioses promote carbon sequestration. Shared genetic mechanisms between fungal and bacterial root endosymbioses exist and a detailed understanding of endosymbionts will be beneficial to drive bioenergy development from trees. The GEBA-RNB project is based on collaboration between JGI and an international consortium from 15 countries coordinated by Wayne Reeve from Murdoch University, Australia.

根瘤菌（Root Nodulating Bacteria，RNB）是一类栖息于土壤中的细菌，在侵染根毛后可与豆科植物形成共生关系。JGI（联合基因组研究所，Joint Genome Institute）发起的“GEBA-RNB”计划，目标是对从全球各地分离得到的100株根瘤菌菌株进行测序。本项目将支持基于序列的系统性研究，以解析生物地理学过程对物种演化的影响，以及根瘤菌共生固氮（Symbiotic Nitrogen Fixation，SNF）的机制。其中，共生固氮过程对全球农业生产力、农业经济与环境可持续性均具有重要价值：它可降低合成氮肥所需的能源消耗，每年可节省约68亿美元；相较于施用人工氮素的集约化农业生产模式，共生固氮可大幅减少温室气体排放；同时还能改善生态环境，具体包括降低旱地盐渍化程度、提升土壤肥力以及防止水体富营养化。根系内共生作用可促进碳固存。真菌与细菌的根系内共生作用共享遗传机制，深入了解内共生体将有助于推动林木生物能源产业的发展。GEBA-RNB项目由JGI与来自15个国家的国际联盟合作开展，该联盟由澳大利亚莫道克大学（Murdoch University）的韦恩·里夫（Wayne Reeve）牵头协调。