Abstract:

The lemongrass plant contains a huge amount of essential oil which had a wide application. It was found that there were great differences between the stem and leaves of lemongrass in essential oil yields. In this paper, we investigated the differential expression protein spots in two-dimensional electrophoresis (2-DE) of lemongrass stem and leaves via K-means clustering. Three parts of lemongrass, flag-leaf, mature-leaf and stem, which were significant different in essential oil contents, were taken to detect the total protein content and analysize the protein expression profiles by 2-DE. K-means clustering of different protein spots was carried out on abundance, isoelectric point (pI) and molecular mass. It was found that the total protein content of flag-leaf and mature-leaf was higher than that of stem, and the total protein content of flag leaf and mature-leaf had little difference. Cluster analysis of the abundance, isoelectric point (pI) and molecular mass of different protein spots in three parts of lemongrass showed that the up-regulated protein spots in flag-leaf and stem were sensitive to molecular weight changes, and the up-regulated protein spots in mature-leaf were more sensitive to abundance changes. Based on this, 15 protein pots were selected and 9 proteins were successfully identified by matrix-assisted laser desorption/ionization (MALDI-TOF/TOF-MS). Our study provides new basic information and research perspective of protein pathway of Cymbopogon citratus essential oil metabolism.

Key words: lemongrass, two-dimensional electrophoresis, K-means clustering analysis, mass spectrometric identification