Identification of aluminum‐responsive proteins in rice roots by a proteomic approach: Cysteine synthase as a key player in Al response

Abstract

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 rice, based on evidence that Al resistance is an inducible process. Two Al treatment systems were applied in the study: Al 31 -containing simple Ca solution culture and Al 31-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 those being up-regulated and 5 down-regulated. Among the up-regulated proteins are copper/ zinc superoxide dismutase (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-aminocyclopropane-1-carboxylate oxidase, G protein b subunit-like protein, abscisic acid-and stress-induced protein, putative Avr9/Cf-9 rapidly elicited protein 141, and a 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, may play a functional role in Al adaptation for rice.

Aluminum triggers broad changes in microRNA expression in rice roots

“…In roots of rice seedlings, expression of genes related to sulfur metabolism, including ATP sulfurylases, are up-regulated in response to Al (Yang et al, 2007). This response is possibly connected to down-regulation of miRNA395, since our analysis showed that miRNA395 expression was reduced after 8 h of Al treatment (Figures 2 and 3).…”

“…Differential display reverse transcription PCR has been used to identify genes that respond to Al in rice cultivars displaying different sensitivities to this metal. Among the genes identified, several were related to signal transduction, ion transport, cellular metabolism, stress, and cytoskeleton rearrangements (Yang et al, 2007). Two genes, OsSTAR1 encoding a nucleotide binding domain, and OsSTAR2, found to be a bacterial-type ABC gene, being expressed mainly in roots, conferred Al tolerance in rice.…”

Ultrastructural and Photosynthetic Response of Populus 107 Leaves to Cadmium Stress

“…In addition, a high concentra- tion of heavy metal treatment induces the production of heavy metal-resistance proteins. They could resist the toxicity of heavy metal [27]. During the later period of treatment, the decline of soluble protein contents could be explained that the Cd-induced oxidative stress appeared [26] and the protein synthesizing machinery was impaired due to the Cd effect [28].…”

Antioxidative responses of cell suspension cultures of two Coffea arabica varieties to low aluminum levels at pH 5.8

“…These enzymes help to protect cells from oxidative stress. GST has been observed to be upregulated in Arabidopsis and rice that have been exposed to Al (Ezaki et al 2004, Yang et al 2007. The GR and GST results clearly indicate that Al is inducing the enhanced activities of the enzymes, which is occurring more dramatically in Icatu.…”