A Preliminary Study On The Different Mechanism Of Salt Tolerance In P. Euphratica And P. Pruinosa

Populus euphratica and Populus pruinosa, sibling to each other in Turanga Section as poplar species (Salicaceae), growing in semi-arid saline areas noted for their high salinity tolerance. There are many researches about physicological changes and moleculer mechanism under salt stress of P. euphratica, but little is known about Populus pruinosa. In this study, by combining growth level and Na+、K+content in two Turanga Populus (P.euphratica and P.pruinosa) calli and the expression level of vacuolar Na+/H+antiporters in different organs of P. euphratica and P.pruinosa were investigated for NaCl-induced, analysed the different mechanism of salt stress in P. euphratica and P. pruinosa.Compared to P.euphratica, P. pruinosa calli grew well in200mM NaCl stress from14d to21d. Increasing the stressed time caused an increase in Na+content concomitant with a decrease in K+content in P.euphratica calli, whereas, the presence of200mM NaCl, K+content has a less increase than7d in14d and21d were detected in P.pruinosa calli. The ratio of K+/Na+in P. pruinosa is higher than in P. euphratica under salt stress for7d,14d and21d, the ratio are1.21and1.67、0.97and1.13、0.83and1.11respective.The transcript levels of six genes coding for NHX-type Na+/H+antiporters suggest that the vacuolar NHX1-6antiporters play an important role response to salt stress in P.pruinosa. Our results suggest that the vacuolar NHX1-6antiporters play an important role both in P. euphratica and P. pruniosa, the relative value of NHX1/2/5in P. pruniosa were upregulated after200mM NaCl stress both in calli and stem, however we detected no NHX2in root. Compared to P. pruinosa, we detected no NHX2in stem about in P. euphratica. These suggest that the NHX2may play a key role in the different mechanism of salt stress in P. euphratica and P. pruinosa.