Proteomic alterations during dormant period of curcuma longa rhizomes

Abstract

Proteins involved during storage of Curcuma longa have not been investigated in detail. Proteins and nucleic acids are considered to be essential for the sprouting period. As numerous applications of proteomic approaches have been reported in many areas of biology, biochemistry and biomedicine, we chose to use proteomic technology to study the protein expression of Curcuma longa (Khaminchun) rhizome during dormancy and sprouting. Microscale solution-phase isoelectric focusing (Zoom) was employed to enrich the low abundance proteins in the pH range of 5.4-10 and improve the separation of those proteins in the acidic range from 3-5.4. Samples were drawn at seven-day intervals from harvest until the commencement of sprouting. The proteomic patterns of the storage period (0, 14, 21, 42, and 70 days) were studied and identified by LC/MS/MS in these two pH ranges. High levels of glyceraldehyde-3-phosphate dehydrogenase, a glycolytic enzyme, were present and in glycosylated and phosphorylated forms. Sporamin, the major storage protein of the tuberous roots of sweet potato, was highly expressed in the dormant period and lower expression was detected in the sprouting period. Moreover, the enzyme for catalyzing the synthesis of catechin, leucoanthocyanidin reductase, was found for the first time in the Curcuma longa rhizome. These results represent the first proteomic patterns during the storage period of Curcuma longa. For the rhizomes of Curcuma longa, visible sprouting was observed within 70 days after harvest. © 2009 Chokchaichamnankit D, et al.