Heat shock proteins(Hsps)have been known as a class of proteins that perform a fundamental role in protecting plants against abiotic stresses,such as drought,salinity,extremely low and high temperatures.However,rare Hsps have been reported and little consideration has been given to the role of Hsps in rice in response to abiotic stress.Therefore,we conducted this research to identify heat shock proteins and reveal the role of sHsps in rice in response to abiotic stresses.First,we combined an orthology-based approach with expression association data to screen rice Hsps,the expression patterns of which strongly correlate with those of heat responsive probe-sets.Twenty-seven Hsp candidates were verified,including 12 small Hsps,six Hsp70s,three Hsp60s,three Hsp90s,and three clpB/Hsp100s.Then,using a combination of interolog and expression profile-based methods,we identified 430 interactorsofHsp70 family members in rice,and validated the interactions by co-localization and function-based methods.Subsequently,13 interacting domains and 28 target motifs were over-represented in Hsp70sinteractors.Twenty-four GO terms of biological processes and five GO terms of molecular functions were enriched in the positive Hsp70 interactors,which expression levels were positively associated with Hsp70s.Analyzing the interaction network of Hsp70s,we found that Hsp70s were involved in macromolecular translocation,carbohydrate metabolism,innate immunity,photosystem II repair and regulation of kinase activities.Hsp26.7,Hsp23.2,Hsp17.9A,Hsp17.4 and Hsp16.9A were up-regulated in rice(Orya sativa L.& Nipponbare)during seedling and anthesis stages in response to heat stress.Subsequently,the expression level of five sHsps in the heat-tolerant rice cultivar,Co39,were all significantly higher than that in the heat-susceptible rice cultivar,Azucena,indicating that the expression level of these five sHsps was positive related to the ability of rice plants to avoid heat stress.Thus,the expression level of these five sHsps can be regarded as bio-markers for screening rice cultivars with different abilities to avoid heat stress.Hsp18.1,Hsp17.9A,Hsp17.7 and Hsp16.9A,in the three rice cultivars under heat stress were found to be involved in one protein complex by Native-PAGE,and the interactions of Hsp18.1 and Hsp 17.7,Hsp18.1 and Hsp 16.9A,Hsp17.7 and Hsp16.9A were further validated by yeast 2-hybridization.Pull down assay also confirmed the interaction between Hsp17.7 and Hsp16.9A in rice under heat stress.In conclusion,the up-regulation of the 5 sHsps is a key step for rice to tolerate heat stress,after that some sHsps are assembled into a large hetero-oligomeric complex.Moreover,we constructed a Protein-Protein Interaction Predictor(PPIP)and a Rice Gene Expression Profile database for experimental biologists.These tools could be available at http://bioinformatics.fafu.edu.cn/yfwang/PPIP/ppip.php and http://bioinformatics.fafu.edu.cn/yfwang/array/index.php respectively.