Submitted to: Plant Biology Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: June 26, 2008
Publication Date: July 2, 2008
Citation: Chen, J., Xin, Z., Burke, J.J. 2008. Roles of FtsH protease in choloroplast biogensis and protection of photosystems from high temperatures stress in higher plants[abstract]. Plant Biology 2008. June 26-July 2, 2008, Merida, Mexico. CDROM. Technical Abstract: AtFtsH11 protease gene is essential for Arabidopsis plant to survive at moderate heat stress. Under high and normal light at 21ºC, ftsh11 mutants were indistinguishable from wild type plants in photosynthesis capability and in overall growth. However, mutant plants display a host of dramatic changes in photosynthesis, cessation of development, and eventual death if temperatures go beyond 30ºC. Thermosensitive phenotypes were observed at all developmental stages and in all green tissues. Cotyledons of mutant seedlings germinated at 21ºC in the dark failed to turn green after being transferred to light at 30ºC. When mutant seedlings were exposed to 30°C, chlorophyll content, chl a/b ratios, PSII quantum yield and ETR decreased significantly while the NPQ and qN increased; the newly formed tissues of mutant plants failed to turn green while already formed leave became chlorotic over a period of a few day with a Fo continuously increase companied by decrease in T1/2. TEM showed abnormal chloroplast development in leaf of high temperature stressed mutant plants. These results suggested that FtsH11 plays critical roles in both the early stages of chloroplast biogenesis and maintaining thermostability of photosynthetic systems at high temperatures. Overexpression of wildtype FtsH11 genes from Arabidopsis and pea was able to complement the thermosensitive phenotypes of ftsh11 mutants, suggesting a conserved role of FtsH11 protease in alleviation of high temperature stress in photosystems of higher plants. The potential substrates of FtsH11 protease in chloroplast are being investigated on 2D Blue native/SDS-PAGE gel by comparing changes of photosynthetic complex and chloroplast proteins between mutant and wildtype and between non-stressed and heat stressed mutant plants.