Post-translational modifications of proteins by small ubiquitin-like modifiers （SUMOs） play crucial roles in plant growth and development, and in stress responses. The MMS21 is a newly-identified Arabidopsis thalian...Post-translational modifications of proteins by small ubiquitin-like modifiers （SUMOs） play crucial roles in plant growth and development, and in stress responses. The MMS21 is a newly-identified Arabidopsis thaliana L. SUMO E3 ligase gene aside from the SIZ1, and its function requires further elucidation. Here, we show that MMS21 deficient plants display improved drought tolerance, and constitutive expression of MMS21 reduces drought tolerance. The expression of MMS21 was reduced by abscisic acid （ABA）, polyethylene glycol （PEG） or drought stress. Under drought conditions, mms21 mutants showed the highest survival rate and the slowest water loss, and accumulated a higher level of free proline compared to wild-type （WT） and MMS21 over-expression plants. Stomatal aperture, seed germination and cotyledon greening analysis indicated that mms21 was hypersensitive to ABA. Molecular genetic analysis revealed that MMS21 deficiency led to elevated expression of a series of ABA-mediated stress-responsive genes, including COR15A, RD22, and P5CS1 The ABA and drought-induced stress-responsive genes, including RAB18, RD29A and RD29B, were inhibited by constitutive expression of MMS21. Moreover, ABA-induced accumulation of SUMO-protein conjugates was blocked in the mms21 mutant. We thus conclude that MMS21 plays a role in the drought stress response, likely through regulation of gene expression in an ABA-dependent pathway.展开更多
The analytical transfer matrix method （ATMM） is applied to calculating the critical radius τc and the dipole polarizability αd in two confined systems： the hydrogen atom and the Hulthēén potential. We find ...The analytical transfer matrix method （ATMM） is applied to calculating the critical radius τc and the dipole polarizability αd in two confined systems： the hydrogen atom and the Hulthēén potential. We find that there exists a linear relation between τe^1/2 and the quantum number nτ for a fixed angular quantum number l, moreover, the three bounds of αd（αd^K,αd^B,αd^U） satisfy an inequality：αd^K≤αd^B≤αd^U,A comparison betwen the ATMM,the exact numerical analysis, and the variational wavefunctions shows that our method works very well in the systems.展开更多
基金supported by the National Natural ScienceFoundation of China (30900789, 31170269)the Ministry of Agriculture (National Key Program for Transgenic breeding 2009ZX08009-006B)the Guangdong Province Universities and Colleges Pearl River Scholar Funded Scheme 2010
文摘Post-translational modifications of proteins by small ubiquitin-like modifiers （SUMOs） play crucial roles in plant growth and development, and in stress responses. The MMS21 is a newly-identified Arabidopsis thaliana L. SUMO E3 ligase gene aside from the SIZ1, and its function requires further elucidation. Here, we show that MMS21 deficient plants display improved drought tolerance, and constitutive expression of MMS21 reduces drought tolerance. The expression of MMS21 was reduced by abscisic acid （ABA）, polyethylene glycol （PEG） or drought stress. Under drought conditions, mms21 mutants showed the highest survival rate and the slowest water loss, and accumulated a higher level of free proline compared to wild-type （WT） and MMS21 over-expression plants. Stomatal aperture, seed germination and cotyledon greening analysis indicated that mms21 was hypersensitive to ABA. Molecular genetic analysis revealed that MMS21 deficiency led to elevated expression of a series of ABA-mediated stress-responsive genes, including COR15A, RD22, and P5CS1 The ABA and drought-induced stress-responsive genes, including RAB18, RD29A and RD29B, were inhibited by constitutive expression of MMS21. Moreover, ABA-induced accumulation of SUMO-protein conjugates was blocked in the mms21 mutant. We thus conclude that MMS21 plays a role in the drought stress response, likely through regulation of gene expression in an ABA-dependent pathway.
基金Project supported by the National Natural Science Foundation of China （Grant No 60237010）, Municipal Scientific and Technological Development Project of Shanghai, China （Grant Nos 012261021 and 01161084） and the Applied Material Research and Development Program of Shanghai, China （Grant No 0111）.
文摘The analytical transfer matrix method （ATMM） is applied to calculating the critical radius τc and the dipole polarizability αd in two confined systems： the hydrogen atom and the Hulthēén potential. We find that there exists a linear relation between τe^1/2 and the quantum number nτ for a fixed angular quantum number l, moreover, the three bounds of αd（αd^K,αd^B,αd^U） satisfy an inequality：αd^K≤αd^B≤αd^U,A comparison betwen the ATMM,the exact numerical analysis, and the variational wavefunctions shows that our method works very well in the systems.
