Molecular Mechanisms Of DEG Protease In Stress In Arabidopsis Thaliana

Plants formed a series of complex and rigid self regulation system to answer the change of environment conditions.Proteolysis is involved in a wide range of processes during the biogenesis and maintenance of chloroplasts.It is a vital homeostatic factor that influences metabolic functions under both optimal and adverse growth conditions.PSII is very sensitive to environment.The PSII reaction center D1 protein being the main target for environment stress induced damage among PSII proteins. Damaged D1 proteins are degraded and subsequently replaced with newly synthesized copies.Many factors trigger the degradation of chloroplast proteins, including changes in environmental conditions,imbalances in the stoichiometry of multisubunit complexes,genetic mutations,and limitations in the availability of cofactors.In Arabidopsis thaliana,DEG5 and DEG8 have a synergistic function in the primary cleavage of the CD loop of the PSII reaction center protein D1,thus,they remain the efficient turnover of PSII.In the interest of study the in vivo function of DEG5, DEG8 and D1 in Arabidopsis thaliana in other adverse growth conditions,we obtained Arabidopsis lines from the SALK collections in which T-DNA was inserted into Deg5 and Deg8,and we got the Deg5/Deg8 double mutant.Both wild type(Col.)and mutants were treated in to analyze the change of D1 protein and chlorophyll a fluorescence,study the function of DEG5 and DEG8 in these environment stresses.Our result indicated that when treated with cold stress,drought stress,salt stress, oxidate stress and osmotic stress,the Fv/Fm reduced both in wild type and the mutant lack of DEG5 and DEG8 protease,and in wild type are slower than single DEG5 or DEG8 mutant,in single DEG mutant are slower than double mutant deg5/deg8.The D1 protein in wild type reduced faster than that in mutant lack of DEG5 and DEG8. DEG5 and DEG8 protease also participate in reducing Dlprotein in these adverse growth conditions.