Pseudomonas stutzeriA1501, associative and endophytic nitrogen-fixing bacterium showed the capacity of colonization in the rice roots and considered as the good colonizer in the rice plant. The experiment was conducte...Pseudomonas stutzeriA1501, associative and endophytic nitrogen-fixing bacterium showed the capacity of colonization in the rice roots and considered as the good colonizer in the rice plant. The experiment was conducted to study the expression of genes potentiality relevant to the association of nitrogen fixing Pseudomonas stutzeri with host rice and reveal the molecular mechanism by which underlying interaction between bacteria and host rice. The bacteria were shown to be uniformly distributed on the rhizoplane of the root and the density of bacteria was found at the intercellular junction and micro colony developed on the surface of the epidermal cells and on the cellular junctions. Root exudates of rice were the major components of carbon and energy sources for bacteria. RT-PCR analyses of pilK, metE, rpoN and fdhE genes expression of P. stutzeri A1501 were performed at positive and negative (control) conditions. After 1 h, it was found that pilK, metE and rpoN transcription were increased 5.7, 6.4 and 3.4-fold, respectively, whereas in the fdhE gene has no expression. Consequently, after 4 h pilk, fdhE, metE and rpoN were decreased -1.9, -4.4, -0.2 and -0.8-fold, respectively. The gene pilK, expression was up-regulation after 1 h and down-regulation after 4 h that has twitching motility to convey the bacterial cell to point of attachment in to host plant. The gene expressions of the bacteria, pilK, metE, rpoN and fdhE were up- and down-regulated during the influence of root exudates which regulated the colonization of bacteria during plant-microbe interaction.展开更多
Pseudomonas stutzeri A1501, an associative nitrogen-fixing bacterium, was isolated from the rice paddy rhizosphere. This bacterium fixes nitrogen under microaerobic conditions. In this study, ge- nome-wide DNA microar...Pseudomonas stutzeri A1501, an associative nitrogen-fixing bacterium, was isolated from the rice paddy rhizosphere. This bacterium fixes nitrogen under microaerobic conditions. In this study, ge- nome-wide DNA microarrays were used to analyze the global transcription profile of A1501 under aerobic and microaerobic conditions. The expression of 135 genes was significantly altered by more than 2-fold in response to oxygen stress. Among these genes, 68 were down-regulated under aerobic conditions; these genes included those responsible for nitrogen fixation and denitrification. Sixty- seven genes were up-regulated under aerobic conditions; these genes included sodC, encoding a copper-zinc superoxide dismutase, PST2179, encoding an NAD(P)-dependent oxidoreductase, PST3584, encoding a 2OG-Fe(II) oxygenase, and PST3602, encoding an NAD(P)H-flavin oxidoreductase. Addi- tionally, seven genes involved in capsular polysaccharide and antigen oligosaccharide biosynthesis together with 17 genes encoding proteins of unknown function were up-regulated under aerobic con- ditions. The overall analysis suggests that the genes we identified are involved in the protection of the bacterium from oxygen, but the mechanisms of their action remain to be elucidated.展开更多
文摘Pseudomonas stutzeriA1501, associative and endophytic nitrogen-fixing bacterium showed the capacity of colonization in the rice roots and considered as the good colonizer in the rice plant. The experiment was conducted to study the expression of genes potentiality relevant to the association of nitrogen fixing Pseudomonas stutzeri with host rice and reveal the molecular mechanism by which underlying interaction between bacteria and host rice. The bacteria were shown to be uniformly distributed on the rhizoplane of the root and the density of bacteria was found at the intercellular junction and micro colony developed on the surface of the epidermal cells and on the cellular junctions. Root exudates of rice were the major components of carbon and energy sources for bacteria. RT-PCR analyses of pilK, metE, rpoN and fdhE genes expression of P. stutzeri A1501 were performed at positive and negative (control) conditions. After 1 h, it was found that pilK, metE and rpoN transcription were increased 5.7, 6.4 and 3.4-fold, respectively, whereas in the fdhE gene has no expression. Consequently, after 4 h pilk, fdhE, metE and rpoN were decreased -1.9, -4.4, -0.2 and -0.8-fold, respectively. The gene pilK, expression was up-regulation after 1 h and down-regulation after 4 h that has twitching motility to convey the bacterial cell to point of attachment in to host plant. The gene expressions of the bacteria, pilK, metE, rpoN and fdhE were up- and down-regulated during the influence of root exudates which regulated the colonization of bacteria during plant-microbe interaction.
基金This work was supported by the National Basic Research Program of China(Grant No.2001CB108904)the Hi-Tech Research and Development Program of China(Grant No.2001AA214021).
基金the National Basic Research Program of China (Grant Nos. 2001CB108904 and 2007CB707805) High-Technology Research Development Program of China (Grant Nos. 2006AA020202 and 2006AA0Z229))
文摘Pseudomonas stutzeri A1501, an associative nitrogen-fixing bacterium, was isolated from the rice paddy rhizosphere. This bacterium fixes nitrogen under microaerobic conditions. In this study, ge- nome-wide DNA microarrays were used to analyze the global transcription profile of A1501 under aerobic and microaerobic conditions. The expression of 135 genes was significantly altered by more than 2-fold in response to oxygen stress. Among these genes, 68 were down-regulated under aerobic conditions; these genes included those responsible for nitrogen fixation and denitrification. Sixty- seven genes were up-regulated under aerobic conditions; these genes included sodC, encoding a copper-zinc superoxide dismutase, PST2179, encoding an NAD(P)-dependent oxidoreductase, PST3584, encoding a 2OG-Fe(II) oxygenase, and PST3602, encoding an NAD(P)H-flavin oxidoreductase. Addi- tionally, seven genes involved in capsular polysaccharide and antigen oligosaccharide biosynthesis together with 17 genes encoding proteins of unknown function were up-regulated under aerobic con- ditions. The overall analysis suggests that the genes we identified are involved in the protection of the bacterium from oxygen, but the mechanisms of their action remain to be elucidated.
