Isolation of drought stress induced genes and proteins in natalgrass (Rhynchelytrum repens) by suppression subtractive hybridization and two-dimensional electrophoresis

Natalgtass, a weed that is widely distributed in the world and resistant to drought stress was subjected to physiological and molecular studies. In the physiological analysis, the relative water content and water potential decreased after 24 hours at treatment with PEG (-1 MPa), while chlorophyll and carotenoid remained similar. In order to identify genes and proteins regulated by drought stress, suppression subtractive hybridization (SSH) and two-dimensional electrophoresis (2-DE) were performed. The cDNAs from natalgrass treated with PEG 6000 (-1 MPa) were used as testers and cDNAs from unstressed natalgrass as drivers for hybridization. We found 33 uniquely expressed sequence tags (ESTs) in the subtractive cDNA library.The predicied proteins of the 33 ESTs are involved in transcription factor, detoxification, protein kinase, protease, transposon, amino acid metabolism, carbohydrate metabolism, TCA cycle, transcription, translation, auxin regulation, circadian clock, cytoskeleton, transporter and unknown protein are considered to be responsible for drought tolerance. In the 2-D gel analysis, 6 proteins were up regulated (DNA-directed RNA polymerase II 19 kDa polypeptide, NBS-LRR type disease resistance protein, tau class GST protein 3, calcineurin B-like protein 3, vetispiradiene synthase and H+-transporting two-sector ATPase delta chain precursor) and 2 proteins were down regulated (eukaryotic initiation factor 4B and ADP-glucose pyrophosphorylase) by the PEG 6000 treatment.