Submitted to: Keystone Symposia
Publication Type: Abstract Only
Publication Acceptance Date: January 25, 2006
Publication Date: April 8, 2006
Citation: Chen, J., Burke, J.J., Velten, J.P., Xin, Z. 2006. Ftsh11 protease plays a critical role in arabidopsis thermotolerance[abstract]. Keystone Symposia. Technical Abstract: Elevated temperature is an environmental stress that often limits plant growth and development. Plants have evolved various mechanisms to alleviate high temperature induced injuries, including the induction of heat shock proteins and increased saturation level of membrane lipids. To identify the various mechanisms of thermotolerance in plants, we have isolated a series of Arabidopsis thaliana thermo-sensitive mutants (atts) that fail to accumulate chlorophyll in cotyledons following a sub-lethal heat treatment of dark grown, 2-d-old seedlings at 38ºC. The gene defined by the atts244 mutant was identified through map-based cloning and encodes a chloroplast targeted FtsH (Filamentous temperature sensitive) protease, atFtsH11. A knockout allele of the atFtsH11 gene identified from the Salk T-DNA Express collection (http://signal.salk.edu/cgi-bin/tdnaexpress) displays thermosensitive phenotype identical to that of atts244 mutant. Photosynthetic capability, measured as chlorophyll accumulation and PSII quantum yield, reduced greatly in leaves of atFtsH11 mutants when they were exposed to a moderately elevated temperature of 31oC. Moreover, the growth and development of the mutant plants are eventually arrested after a prolong exposure to 31ºC, while, under identical conditions, wild-type plants continue to grow and complete their life cycle. Disruption of atFtsH11 has little effect on plant tolerance to high light stress. FtsH protease is involved in degradation of the heat shock regulator '32 and phage labda cII protein in E. coli. FtsH homologues in bacteria and yeast are involved in cell cycle control, membrane protein assembly, protein translocation, regulation of gene expression, and play critical roles in heat tolerance, salt tolerance and other stress responses. The Arabidopsis genome contains 12 predicted FtsH proteases. All the previously characterized atFtsHs play roles in light stress responses relation to the degradation of unassembled thylakoid membrane proteins and photodamaged PSII D1 protein, and the chloroplast biogenesis. Here we present the first evidence of the important role of FtsH in thermotolerance in higher plants.