Bhagwat A A, Keister D L
Soybean and Alfalfa Research Laboratory, Agricultural Research Service, Beltsville, Maryland 20705-2350.
Appl Environ Microbiol. 1992 May;58(5):1490-5. doi: 10.1128/aem.58.5.1490-1495.1992.
The growth of Bradyrhizobium japonicum USDA 110 and USDA 438 in soil extract-supplemented medium led to transcription of a large amount of DNA not expressed in basal medium. Strain USDA 438 was more competitive for the nodulation of soybean than strain USDA 110. To identify and isolate DNA regions which were expressed specifically in strain USDA 438 but not in strain USDA 110 in response to soil extract or soybean root exudate, we developed a subtractive RNA hybridization procedure. Several cosmid clones which showed strain-specific gene expression were isolated from a USDA 438 gene library. Two clones enhanced competitive nodulation when mobilized to USDA 110. The method described may be useful for identifying genes expressed in response to environmental stimuli or genes expressed differently in related microbial strains.
慢生根瘤菌USDA 110和USDA 438在添加土壤提取物的培养基中生长，导致大量在基础培养基中未表达的DNA转录。菌株USDA 438在大豆结瘤方面比菌株USDA 110更具竞争力。为了鉴定和分离在菌株USDA 438中特异性表达而在菌株USDA 110中不表达的DNA区域，以响应土壤提取物或大豆根分泌物，我们开发了一种消减RNA杂交程序。从USDA 438基因文库中分离出几个显示菌株特异性基因表达的黏粒克隆。当转移到USDA 110时，两个克隆增强了竞争结瘤能力。所描述的方法可能有助于鉴定响应环境刺激而表达的基因或在相关微生物菌株中差异表达的基因。
