18 KDa PROTEIN ACCUMULATION IN SUGARCANE LEAVES UNDER DROUGHT STRESS CONDITIONS

The alteration of protein synthesis or degradation is one of the fundamental metabolic processes that affects drought tolerance. To investigate the protein profiles of sugarcane exposed to drought stress, two unrelated lines of sugarcane (Saccharum officinarum L.) Khon Kaen 1 and  K86- 161were subjected to progressive water stress for 20 days. Under progressive drought stress condition, the Khon Kaen 1 line is sensitive to water stress. The modification of leaves were observed 2 weeks after the onset of water deficit. The Khon Kaen 1 leaves gradually turned yellow and wilted whereas the K86-161 leaves from the tolerant line remained green. The relative water content (RWC) in Khon Kaen 1 was decreased to 60% on day 20th whereas the RWC of K86-161 was slightly decreased and remained constant at 86% upon exposure to the water stress. In addition, when the protein changed in leaves were studied by two-dimensional electrophoresis, the accumulation of a 18 kDa protein was detected in drought-tolerant, K86-161 line. Antiserum raised against this protein, purified from SDS-PAGE, was used as a probe to detect the protein in sugarcane leaves by Western blotting technique. The titer of antigen-antibody interaction, was estimated to be 1:100. Furthermore, this polyclonal antibody was used to detect the accumulation of the 18 kDa protein in K86-161 and Khon Kaen 1 sugarcane leaves by Western blotting technique. The results show that the 18 kDa protein band from K86-161 expressed higher intensity than that of Khon Kaen 1 in equivalent to total protein amount. These results indicate that  18 kDa protein expressions had a high potential for development as a marker in any screening technique for drought-tolerant sugarcane cultivars.  

Keywords: sugarcane, drought tolerance, polyclonal antibody, western blotting technique

Corresponding author: E-mail: somkly@kku.ac.th