Soil pH is a main factor that affects the nodule formation and nitrogen fixation. The largely reduced nitrogen fixation effect caused by acid soil is the ma- jor limitation of alfalfa growth in the south of China. Thu...Soil pH is a main factor that affects the nodule formation and nitrogen fixation. The largely reduced nitrogen fixation effect caused by acid soil is the ma- jor limitation of alfalfa growth in the south of China. Thus selection of anti-acid nodule for inoculating on alfalfa is of great significance in practical production. Using nine candidate rhizobia ( Rhizobium meliloti L. ) as study objects, their colony diameters and the nodule number of each strain inoculated alfalfa variety were investigated at different pH conditions. The YNCY006 strain presented the strongest resistance to acid, while YNCY007 strain presented the weakest. For nedulation, GT13R alfalfa inoculated with YNCY006 or YNCY008 strains was the best symbiosis system in the acidic soil.展开更多
The 660 bp region between nodD3 P1 promoter and the following coding region of Rnizopium meliloti has been studied. This region is designated 'downstream sequences' . it consists of two potential open reading ...The 660 bp region between nodD3 P1 promoter and the following coding region of Rnizopium meliloti has been studied. This region is designated 'downstream sequences' . it consists of two potential open reading frames, ORF1 and ORF2. Studies on the role of the downstream sequences on the activity of nooD3 P1 with nod D3(P1)-/acZ fusion show that deletion of the seguences containing ORF2 causes the increase of the activity of the fusion; on the contrary, addition of extra copies of ORF2 markedly decreases the activity of the fusion. These results indicate that the product of ORF2 plays a negative role in the expression of nod D3.展开更多
基金Supported by National Natural Science Foundation of China(31060324)Natural Science Foundation of Yunnan Province(2012FB148,2008CD031)Natural Science Key Fund of Yunnan Provincial Education Department(2012Z021)
文摘Soil pH is a main factor that affects the nodule formation and nitrogen fixation. The largely reduced nitrogen fixation effect caused by acid soil is the ma- jor limitation of alfalfa growth in the south of China. Thus selection of anti-acid nodule for inoculating on alfalfa is of great significance in practical production. Using nine candidate rhizobia ( Rhizobium meliloti L. ) as study objects, their colony diameters and the nodule number of each strain inoculated alfalfa variety were investigated at different pH conditions. The YNCY006 strain presented the strongest resistance to acid, while YNCY007 strain presented the weakest. For nedulation, GT13R alfalfa inoculated with YNCY006 or YNCY008 strains was the best symbiosis system in the acidic soil.
文摘The 660 bp region between nodD3 P1 promoter and the following coding region of Rnizopium meliloti has been studied. This region is designated 'downstream sequences' . it consists of two potential open reading frames, ORF1 and ORF2. Studies on the role of the downstream sequences on the activity of nooD3 P1 with nod D3(P1)-/acZ fusion show that deletion of the seguences containing ORF2 causes the increase of the activity of the fusion; on the contrary, addition of extra copies of ORF2 markedly decreases the activity of the fusion. These results indicate that the product of ORF2 plays a negative role in the expression of nod D3.