The Role Of Arabidopsis Ubiquitin C-terminal Hydrolase Gene In Plant Stress Response

Ubiquitin carboxy terminalhydrolases(UCHs)is a deubiquitination enzyme and widely exist in most organisms,which can release ubiquitin molecules from the substrate protein.UCHs can promote the recycling of ubiquitin by reverse adjustment protein degradation.Recent studies have found that UCHs play an important role in metabolic regulation,immune response,signal transmission,transcriptional control,stress response,and DNA repair.In our previous study,it was found that the AtUCH4 gene probably fuctions in abiotic stresses.Therefore,we make experiments with wild type(Col-0),mutation type(uch4),resorting mutation plant(UU5-1 and UU7-1).These experiments include seed germination rate,cotyledon greening rate,root inhibition test and how salt stress effects of flowering time of Arabidopsis thaliana.We hope that these experiments can make the contribution for the study of abiotic stress tolerance about plant.The main results that we obtained are as follows:1.The seeds(genotype is Col-0,uch4,UU5-1 and UU7-1)were plated on 1/2 MS medium supplemented with 0 mM,50 mM,100 mM,150 mM and 200 mM NaCl respectively,and the germination rates were counted.The result turned out that the germination rates of UU5-1 and UU7-1 plants were almost the same as that of Col-0 plants under various conditions.In contrast,NaCl inhibited seed germination in the uch4 plants more severely than in Col-0 plants,especially at 100 mM and 150 mM NaCl(Fig.5a).Then,the AtUCH4 gene plays an important role in the process of salt-stress-response during germination stage.2.The seeds(genotype is Col-0,uch4,UU5-1 and UU7-1)were placed on 1/2 MS medium containing 0 m M,50 mM,100 mM,150 mM and 200 mM NaCl respectively,and cotyledon greening rates were counted.We found,compared with Col-0,cotyledon greening rate of uch4 is decreasing and cotyledon greening rate of UU5-1,UU7-1 were not significantly different in the one-half MS agar plates which the salinity is 100 mM or 150 mM.This shows that,the AtUCH4 worked in salt-stress-response during late germination stage.3.The seeds(genotype is Col-0,uch4,UU5-1 and UU7-1)were plated on 1/2 MS medium.The seedlings were transplanted to 1/2MS medium with 0 mM,50 mM,100 mM,150 mM and 200 mM NaCl respectively after two days,and the taproot length of seedlings were measured a few days later.We found that the taproot length of uch4 was short than Col-0 and the taproot length of UU5-1,UU7-1 were not significantly different in the 1/2 MS medium which the salinity is 100 mM or 150 mM.The results shown that,the AtUCH4 worked in salt-stress-response during seedlings growth stage.4.Transplanted this seedlings(genotype is Col-0,uch4,UU5-1 and UU7-1)to the nutrient soil,and irrigated them by 200 mM NaCl solution,created an environment of high salinity and counted the time of bolting and flowering.We found that the time of bolting and flowering of uch4 was putting off obviously,the number of rosette leaves significantly reduced,plant was short,growth cycle was extension.The time of bolting and flowering in Col-0,UU5-1 and UU7-1 were also slightly putting off.This phenomenon shows,the AtUCH4 worked in salt-stress-responding during reproduction.5.The seeds(genotype is Col-0,uch4,UU5-1 and UU7-1)were placed on 1/2 MS medium with 0 ?M,0.5 ?M,1 ?M,2 ?M and 5 ?M ABA respectively,and the germination rates were counted.The result turned out that,compared with Col-0,germination rate of uch4 is decreasing and germination rate of UU5-1,UU7-1 were not significantly different in the one-half MS agar plates which concentration of ABA is 1?M or 2 ?M.This shows that,AtUCH4 gene plays an important role in the process of ABA-stress-response during germination stage.6.The seeds(genotype is Col-0,uch4,UU5-1 and UU7-1)were plated on 1/2 MS medium with 0 ?M,0.5 ?M,1 ?M,2 ?M and 5 ?M ABA respectively,and cotyledon greening rates were counted.We found,compared with Col-0,cotyledon greening rate of uch4 is decreasing and cotyledon greening rate of UU5-1,UU7-1 were not significantly different in1/2 MS medium which the concentration of ABA is 1?M or 2 ?M.This shows that,the AtUCH4 worked in ABA-stress-response during during seedlings growth stage.7.The seeds(genotype is Col-0,uch4,UU5-1 and UU7-1)were plated on the 1/2 MS medium.The seedlings were transplanted to 1/2 MS medium with 0 ?M,0.5 ?M,1 ?M,2 ?M and 5 ?M ABA respectively,after two days,and the taproot length of seedlings were measured a few days later.We found that the taproot length of uch4 was short than Col-0 and the taproot length of UU5-1,UU7-1 were not significantly different in the one-half MS agar plates which the concentration of ABA is 1?M or 2 ?M.The results shown that,the AtUCH4 worked in ABA-stress-response during late germination stage.