SUMMARYhMMS21 is a SUMO E3 ligase required for the prevention of DNA damage-induced apoptosis, and acts by facilitating DNA repair in human cells. The Arabidopsis genome contains a putative MMS21 homologue capable of interacting with the SUMO E2 conjugating enzyme AtSCE1a, as indicated by a yeast two-hybrid screen and bimolecular fluorescence complementation experiments. In vitro and in vivo data demonstrated that AtMMS21 was a SUMO E3 ligase. We identified the Arabidopsis AtMMS21 null T-DNA insertion mutant mms21-1, which had a short-root phenotype, and affected cell proliferation in the apical root meristem, as indicated by impaired expression of the cell division marker CYCB1:GUS in mms21-1 roots. The mms21-1 roots had reduced responses to exogenous cytokinins, and decreased expression of the cytokinin-induced genes ARR3, ARR4, ARR5 and ARR7, compared with the wild type. Thus, our findings suggest that the AtMMS21 gene is involved in root development via cell-cycle regulation and cytokinin signalling.
BackgroundMMS21 is a SUMO E3 ligase that is conserved in eukaryotes, and has previously been shown to be required for DNA repair and maintenance of chromosome integrity. Loss of the Arabidopsis MMS21 causes defective meristems and dwarf phenotypes.ResultsHere, we show a role for AtMMS21 during gametophyte development. AtMMS21 deficient plants are semisterile with shorter mature siliques and abortive seeds. The mms21-1 mutant shows reduced pollen number, and viability, and germination and abnormal pollen tube growth. Embryo sac development is also compromised in the mutant. During meiosis, chromosome mis-segregation and fragmentation is observed, and the products of meiosis are frequently dyads or irregular tetrads. Several transcripts for meiotic genes related to chromosome maintenance and behavior are altered. Moreover, accumulation of SUMO-protein conjugates in the mms21-1 pollen grains is distinct from that in wild-type.ConclusionsThus, these results suggest that AtMMS21 mediated SUMOylation may stabilize the expression and accumulation of meiotic proteins and affect gametophyte development.
Due to the large investment, long construction period, and extensive coverage of power grid engineering projects, it is common for project settlement and completion acceptance to lag behind. Therefore, it is of great significance to realize the reasonable control of the cost of power grid enterprises to do a good job in the transfer of power transmission and transformation projects in a timely manner and avoid the risk of transfer. Combining the current status of capital transfer in power transmission and transformation projects, and relying on the identification of key points of capital transfer in different construction stages of power transmission and transformation projects, this paper innovatively proposes a risk index system for capital transfer, and further uses the analytic hierarchy process to determine the index weights, and then uses the fuzzy TOPSIS method to construct an evaluation The model can realize the effective assessment of capital transfer risk, which can provide reference and support for improving the efficiency of capital transfer of power transmission and transformation projects in an all-round way. Finally, the operability and scientificity of the evaluation index system and evaluation method are verified by the form of an example.
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