| Drought stress is the key factor that affects plant survival and reproduction.The plant drought regulation mechanism is extremely complex,the external environmental factors and internal genetic factors produce various signals to regulate the plant response to drought stress.In the previous studies,it was found that the F-box gene FOF2 in Arabidopsis responded to abiotic stress and played a positive regulatory role in response to drought stress,but its regulation mechanism was not clear.In this paper,FOF2 overexpression,the mutant fof2-1 and the double mutant fof2foll were selected and assayed at the molecular mechanism of FOF2 that response to drought stress.The results were as following:(1)The mutant fol1 of FOL1 in FOF2 homologous gene was treated with drought,and fol1 was found without drought phenotype.The double mutant fof2fol1 were treated with drought,and it was found that the double mutant fof2foll were hypersensitivity to drought stress,and the drought tolerance was significantly weaker than the wild type.Under drought stress,the water loss rate was higher in fof2foll double mutant compared with wild type.It indicates that FOF2 and FOL1 may have functional redundancy in response to drought.(2)Under drought stress,the ABA content of fof2-1 and fof2fol1 mutant was detected.The results shows that the ABA content in the mutants was lower than that in the wild type.Moreover,the FOF2 gene expression induced drought or ABA was absent in abi2-1,which is an ABA-insensitive mutant.This preliminarily indicates that FOF2 regulates the drought resistance of plants through ABA signaling pathway.(3)The response of ABA to the germination and seedling growth of FOF2 overexpressing lines and mutants was further examined.It was found that the MycFOF2ox overexpressing line were less sensitive to ABA in the main root elongation,seed germination and cotyledon greening,the mutants fof2-1 and fof2fol1 were more sensitive to ABA and significantly inhibited.This shows that FOF2 plays a negative regulatory role in ABA-mediated inhibition of seed germination,cotyledon greening,and main root elongation.(4)The expression levels of ABI3 and ABI5 during the germination of FOF2 overexpressing lines and mutant seeds were detected.It was found that the expression levels of ABI3 and ABI5 in MycFOF2ox overexpressing lines were lower than wild type,but the expression levels in fof2-1 was higher.The expression of FOF2 during the germination of ABA-insensitive mutants abi3-4 and abi5-1 was detected and the expression of FOF2 was decreased.This suggested that FOF2,ABI3 and ABI5 affect each other during seed germination.Genetic analysis showed that the phenotype of fof2follxabi3-4 mutant was consistent with the double mutant fof2fol1 in seed germination showing sensitivity to ABA.It suggests that FOF2 is located downstream of ABI3 and regulates seed germination.(5)RNA-seq was used to analyze the transcriptional expression pattern of FOF2-overexpressing strain MycFOF2ox.The results showed that the expression of large number with abiotic stress-responsive genes were significant changes in FOF2-overexpressing plants,including multiple drought-and ABA-response-related genes.Real-time fluorescence quantitative PCR analysis of some of these genes,such as AT2G40170,AT247770,AT1G32560,and.AT2G30580,confirmed that these genes are transcribed in FOF2 overexpressing plants.This laid a foundation for further research on the precise molecular mechanism of FOF2 regulating plant drought tolerance.The above results indicate that FOF2 responds to drought stress through the ABA signaling pathway and is located downstream of ABI3 to regulate seed germination... |
PDF Full Text Request