Salt resistant plants are able to exclude Na+ in a selective manner from their plasma membrane during initial phase of salinity which is encountered during first phase . Cell membranes are selectively permeable and can undertake transport of ions against the gradient. When the plants encounter salinity , a signal is percieved in plants and they try to accummulate osmolytes to balance the higher concentraions outside the call cytoplasm and also undertake exclusion of Sodium through cell membrane . ATPase plays an important role in this process as demonstrated by Professor Dr Sven Schubert and his group from Institue of Plant Nutrition Giessen Germany. However how do the plants perceive that the salinity outside the plant has increased. What is the mechanism of signal transduction with respect to salinity signals. Plants do not have endocrine system but do plants hormones like ABA help perceive the signals ?