Analysis of heat-stress responsive genes in Aneurolepidium chinense leaves by differential display

Wild plants experience more severe abiotic stresses such as heat, cold, drought and salinity than crop plants do under natural environments and have developed more particular adaptation mechanisms. In order to understand those mechanisms for thermotolerance, we carried out a large scale screening of heat-stress inducible genes by differential display using 480 species of randomly amplified polymorphic DNA (RAPD) primers from the leaves of a semiarid plant (Aneurolepidium chinense (Trin.) kitag), which can grow vigorously under high temperature, drought and salinity conditions. A comparative analysis of gene expression between control and stress conditions led to the detection of 91 cDNA clones from heat-stressed plants. DNA sequence analysis and database searching revealed that 21 cDNA clones induced by heat stress have homology to known proteins. On the other hand, triple as many (75% of the total isolated clones) had homology to either putative or unknown proteins. Identified genes included those encoding proteins involved in signal transduction (PIP5kinase, receptor protein kinase, etc.), heat shock proteins, protein synthesis, and other enzymes related to abiotic stress. The stress induction in most of the candidates were confirmed at the transcriptional level, but some encoding signal transduction kinases could not be detected by Northern blot analysis. It showed that differential display is a powerful tool for cloning cDNAs induced by heat stress and these results thus obtained are useful for understanding the plant thermotolerance mechanism.