The Functions Of Wheat F-box Gene TaFBA1 In Plant Salt Tolerance

Soil salinization is a worldwide ecological problem.At present,the global salinization area has reached 950 million hectares.To make full use of the land resource and to ensure the food security,it is necessary for us to improve plant salt tolerance.Skp1-Cullin-F-box(SCF)complex is a kind of important ubiquitin E3 ligase,which is a main determinant of substrate specificity in UPS.And F-box protein,as a major subunit of SCF complex,is known to play an important role in response to abiotic stresses.We previously isolated an F-box gene,Ta FBA1,from Triticum aestivum L.cv.To explore the function of E3 ligase gene Ta FBA1 in Wheat under abiotic stress,we transformed and obtained transgenic tobacco.This study analyzed the salt resistance of transgenic tobacco and its mechanism.The main results are as follows:(1)A variety of methods,including PCR detection,Western blot and E3 ligase activity levels,were used to identify overexpression of Ta FBA1 transgenic tobacco,the results showed that Ta FBA1 expressed in tobacco successfully and transgenic tobacco improved the protein level and E3 ligase activity under salt stress.(2)We selected different concentrations of Na Cl to treat transgenic tobacco on different growth ages.The results showed that the germination rate and root elongation of the transgene plant were increased compared with WT.Under the long-term salt stress,the biomass accumulation of transgenic plant was significantly higher than WT.At the same time,transgenic tobacco kept highter photosynthesis ability under salt stress.In a word,the results showed that the overexpression of wheat Ta FBA1 gene enhanced the plant salt tolerance.(3)We analyzed the mechanism of increased the salt tolerance in transgenic tobacco from the physiological biochemical and molecular level.The results showed that transgenic tobacco had higher antioxidant capacity compared with WT.Under salt stress,the content of H2O2 and O2·-production rate in transgenic tobacco were lower than WT;the MDA content and electrolyte leakage rate in transgenic tobacco were lower than WT.All the results indicted that the membrane transgenic tobacco was more stable.Under salt stress,Superoxide dismutase(SOD),catalase(CAT)and peroxidase(POD)activity in transgenic lines were higher than WT,which indicated that the improvement of salt tolerance in transgenic tobacco may be related to the improvement of antioxidant capacity.(4)We also analyzed the accumulation and flux of Na+and K+ in roots and leaves cell.The results showed that Na+ content of transgenic lines was lower than that of WT,while the content of K+ is higher in transgene lines than WT under salt stress.That indicated that the rate of Na+/K+ in transgenic lines was lower than WT.We detected the Na+ and K+ dynamic flow in 10 min,found that transgenic tobacco promotes Na+ efflux and uptake of K+,corresponding to the prophase Na+ and K+ content.(5)Under salt stress,the plasma membrane H+-ATPase activity was higher in transgenic plants than WT,which was contributed to improve the Na+ discharge rate and reduce the accumulation of Na+ in plants.The vacuole membrane V-ATPase and PPase activity were higher in transgene plants than WT,which was beneficial to the localization of Na+ in cells.These results suggest that the enhancement of salt tolerance in transgenic tobacco may be related to the regionalization of ions.(6)We analyzed the gene expressing level of transgenic tobacco under salt stress,including Na+ antiporter genes(NtHKT521,NtHKT555 and NtHKT586),stress protein(NtERD10C and Nt ERD10D)genes and antioxidant related genes(Nt POD and NtSOD).These genes were up-regulated under salt stress.(7)We used the Arabidopsis homolog mutant atfbw2-4 to analyze the effect of Ta FBA1 mutation on salt stress.When treated with 200 m M NaCl,the growth and biomass of Arabidopsis plants was inhibited and the leaves turned yellow,and this change in phenotype was more serious in mutant plants than that in WT plants.It indicted that the mutation of Ta FBA1 gene in Arabidopsis thaliana led to more significant sensitivity to salt stress.The above results showed that wheat F-box protein gene Ta FBA1 played an important role in plant salt stress.Overexpression of Ta FBA1 gene enhanced salt tolerance of transgenic tobacco.Ta FBA1 gene mutation in Arabidopsis thaliana led to higher sensitivity to salt stress than WT.Due to the overexpression of Ta FBA1,the enhanced salt tolerance in transgenic tobacco may related to the high antioxidant capacity and the ions regionalization capacity.