The Study Of The Gas Exchange And FtsH Gene Expression In Bayberry (Myrica Rubra Sieb.et Zucc.) Under High Temperature And Strong Light

This paper by biennial ’Dongkui’ and ’Tanmei’ of bayberry (Myrica rubra Sieb. Et Zucc.) pottedseedlings as experimental material, studied leaf gas exchange parameters change and FtsH proteasewhich regulating D1protein turnover and its coding gene expression under different temperatures (25,30,35,40°C) and light intensity (500,1000,1500μmol.m-2.s-1), to clarify under high temperature andstrong light conditions bayberry leaves physiological and molecular mechanism of photoinhibition.Main results are as follows:1.10-25°C temperature range makes Pn rise and35-43°C was opposite in800μmol.m-2.s-1intensity.It explains only thermal stress can make the bayberry produces more serious photoinhibition undersaturated light intensity. Compared with25°C+500μmol.m-2.s-1, Pn and AQY of two bayberry’ leavesdecreased obviously increase under40°C+1500μmol.m-2.s-1intensity, and the ’Dongkui’ drop of lessthan ’Tanmei’, that shows high temperature and strong light intensified the degree of photoinhibition leaf,’Dongkui’ more resistant to high temperature and strong stress than ’Tanmei’.2. The full length cDNA cloned to bayberry ftsH gene, the gene and plants such as Arabidopsisthaliana ftsH genes of the amino acid sequence similarity of about97%, nucleotide similarity of about90%. Studies the subcellular localization, determine MrftsH gene in cell plays a role in the part of theplasmid.3. It was discovered that the expression level of ftsH gene increases with light intensity; But whichwas higher under500μmol.m-2.s-1than1500μmol.m-2.s-1at40°C. Moreover,‘Dongkui’ was thecultivar having significantly higher expression level of the ftsH gene than ‘Tanmei’ under strong lightand heat stresses, this is likely to be an important reason that ‘Dongkui’ may more resistant than‘Tanmei’ for the high temperature and bright light stress.4. Under25°C optimum temperature, FtsH protease content at1500μmol.m-2.s-1is1.7times thanunder500μmol.m-2.s-1. Shows that in the absence of temperature stress environment, FtsH proteaseplays an important role in the D1protein turnover under strong light. Compared with25°C+500μmol.m-2.s-1, FtsH protease and Deg1protease expression reduction in the amount ofincrease under40°C+1500μmol.m-2.s-1, this suggests that FtsH protease and Deg1protease playimportant roles in the D1protein turnover.