Poster: Temperature responses

Abs # 127: The expression profile of rice class I small HSP gene family in response to cytotoxic agents induced HS-like response

Presenter:	Lin, Chu-Yung , chuyung@ntu.edu.tw
Authors	Guan, Jiahn-Chou  (A)   Feng, Shi-Pin  (A)   Jinn, Tsung-Luo  (A)   Lin, Chu-Yung  (A)
Affiliations:	(A): Institute of Plant Biology, National Taiwan University

In rice (Oryza sativa Tainung No.67), the class I small HSP gene family consists of nine members. Five genes were clustered on chromosome 1 and the others on chromosome 3. All members of the gene family were expressed upon heat shock treatment. To examine whether cytotoxic agents induced HS-like response have the same effect as heat shock, we monitor the expression of these genes by RT-PCR including arsenite (As), cadmium (Cd), ethanol, and a proline analogue (azetidine-2-carboxylic acid, Aze). Interestingly, the expression profiles in response to these agents were more diverse than those evoked by heat stress. With the exception of Oshsp16.9D and Oshsp17.9B, the other seven members of the family located on both chromosome 1 and 3 were strongly induced by As. In contrast, upon Cd, ethanol, and Aze treatment, only members on chromosome 3 were strongly induced. Particularly, the transcripts for Oshsp17.3 and Oshsp18.0 were accumulated much more than other genes by these chemicals. The same expression profile could be evoked by H₂O₂ and CuCl₂ treatments, though the expression level was lower than that of chemical treatments. Transient expression analyses of the promoters from genes on both chromosomes also indicated that cis-responsive elements other than HSE might play a selective role in the expression of these genes by chemical stressors. In summary, the differential expression pattern portends different induction pathways among members of class I sHSPs under HS and HS-like responses and H₂O₂ may be involved in the differential induction pathways.