Aluminum(Al)toxicity is a serious limitation to worldwide crop production.Rice is one of the most Al-tolerant crops and also serves as an important monocot model plant.This study aims to identify Al-responsive proteins in flee，based on evidence that Al resistance is an inducible process.Two Al treatment systems were applied in the study：Al3+-containing simple Ca solution culture and Al3+-containing complete nutrient solution culture.Proteins prepared from rice roots were separated by 2-DE.The 2-DE patterns were compared and the differentially expressed proteins were identified by MS.A total of 17 Al-responsive proteins were identified，with 12 of which being up-regulated and 5 down-regulated.Among the up-regulated proteins are Cu-Zn SOD，GST and S-adenosylmethionine synthetase 2，which are the consistently known Al-induced enzymes previously detected at the transcriptional level in other plants.More importantly,a number of other identified proteins including cysteine synthase(CS),1-aminecyclopropane-1-carboxylate oxidase，G protein β subunit-like protein,ABA-and stress-induced protein，putative Avr9/Cf-9 rapidly elicited protein 141 and 33 kDa secretory protein are novel Al-induced proteins.Most of these proteins are functionally associated with signaling transduction，antioxidation and detoxification.CS，as consistently detected in both Al stress systems，was further validated by Western blot and CS activity assays.Moreover,the metabolic products of CS catalysis，I.E.Both the total glutathione pool and reduced glutathione,were also significantly increased in response to Al stress.Taken together,our results suggest that antioxidation and detoxification ultimately related to sulfur metabolism，particularly to CS，mayplayafunctional role in Al adaptation for rice.