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Representative western blotting results of the three H-NS family proteins. The amounts of TurA, TurB, and His-tagged Pmr were monitored at various points in the growth curve of KT2440 (A), KT2440(pCAR1) (B), and KT2440(pCAR1pmrHis) (C). Results of western blotting analyses using anti-TurA (left panels in A and B), anti-TurB (right panels in A and B), and anti-His antibodies (C) are shown in the black boxes. The loading amounts of whole cell protein were 80 μg for KT2440 and KT2440(pCAR1) and 40 μg for KT2440(pCAR1pmrHis) per lane. Specific amounts of purified His-tagged proteins (shown in red) were used to quantify the number of protein molecules. For each strain, 5 μg of whole cell protein were loaded and detected by anti-RNA polymerase α subunit (RNAP) antibody (green boxes) as a loading control. (PDF 83 kb)

Sweet sorghum is a C4 plant with high efficiency of photosynthesis and accumulation of photosynthetic products during growth stage. Until now, little is known about photosynthetic characteristics of sweet sorghum subjected to heavy metal contaminated soil. In this study, photosynthetic modification of sweet sorghum was measured in response to cadmium (Cd) under greenhouse conditions. The experiment was concentrated specifically on Keller (KE) and E-Tian (ET), two cultivars of sweet sorghum. The plants subjected to 100 mg/kg Cd in soil were compared with the control plants without Cd treatment. The results indicated that both cultivars of sweet sorghum display similar photosynthetic responses to Cd exposure. The high Cd concentration resulted in significant decline of photosynthesis net rate (Pn). Pn of ET declines more than Cd-treated KE plants. Moreover, Cd-treated plants were detected to have lower stomata conductance (gs) and intercellular CO2 concentrations (Ci) than control plants. Chlorophyll content also displayed significant differences between control and Cd-treated plants. In ET, the reduction of both chlorophyll-a and chlorophyll-b was observed under Cd stress, compared with the controls. In contrast, chlorophyll content was significantly enhanced by Cd stress in KE. In conclusion, through the comparison between two sweet sorghum cultivars, it is demonstrated the photosynthetic activity of ET more sensitive to Cd stress than that of KE. Therefore, KE has a potential for biofuel production and phytoremediation of heavy metal in soil.

Ralstonia solanacearum is the second most destructive bacterial plant pathogens worldwide and HrpG is the master regulator of its pathogenicity. PrhG is a close paralogue of HrpG and both belong to OmpR/PhoB family of two-component response regulators. Despite a high similarity (72% global identity and 96% similarity in helix-loop-helix domain), they display distinct roles in pathogenicity. HrpG is necessary for the bacterial growth in planta and pathogenicity, while PrhG is dispensable for bacterial growth in planta and contributes little to pathogenicity. The main difference between HrpG and PrhG is the 50-amino-acid-long C-terminal extension in PrhG (amino-acid residues 230-283), which is absent in HrpG. When this extension is deleted, truncated PrhGs (under the control of its native promoter) allowed complete recovery of bacterial growth in planta and wild-type virulence of hrpG mutant. This novel finding demonstrates that the extension region in PrhG is responsible for the functional difference between HrpG and PrhG, which may block the binding of PrhG to target promoters and result in impaired activation of hrp expression by PrhG and reduced virulence of R. solanacearum.

Sweet sorghum has become a candidate species for combining phytoremediation with biofuel production due to heavy metal resistance, great biomass and sugar enrichment in stem. However, the influence of heavy metals on sugar accumulation in sweet sorghum is still unknown. In this study, Cd induced modification of sugar storage and translocation in stem was monitored using two sweet sorghum cultivars Keller (KE) and E-tian (ET). Brix degree, which represents sugar content in stem juice, displays significant reduction in response to exogenous Cd treatment in both lines. The sugar enrichment is more obviously repressed in the lower internodes while it is hardly affected in the top internodes. Excessive Cd results in drastically enhanced Cd accumulation, preferentially in the lower internodes. More interestingly, negative correlation between Cd and sugar content is detected along internodes, indicating antagonistic translocation between Cd and sugar along stem of sweet sorghum. The preferential compartmentation of Cd and sugar in different regions of stem provides novel insights into understanding and application of sweet sorghum for combining biofuel production with phytoremediation of heavy metal in soil.

第25回宇宙利用シンポジウム(2009年1月14日-15日, 宇宙航空研究開発機構宇宙科学研究本部相模原キャンパス), The Twenty-fifth Space Utilization Symposium (January 14-15, 2009: ISAS/JAXA Sagamihara, Japan), The working group discussed to assess the energy saving organic waste water process associated with food production on the space station and to examine problems to carry out. The organic waste is also one of the important biomass resources in closed system such as the space station. To construct sustainable carbon recycling system, waste water process and food production should be associated. Energy saving concept is important to trouble tolerant system. Our working group discussed to construct the system works under the gravity-independent environments., 形態: カラー図版あり, 資料番号: AA0064297029