Drought and salinity are two major limiting factors in cotton productivity in West Texas. One way to reduce cotton loss caused by drought and salinity is to increase sodium concentration in the vacuoles of cotton cells, so that the water potential is more negative inside cells, which draws water to move into cells and avoids accumulation of sodium ions to toxic level in cytoplasm, therefore achieving better water retention and higher salt tolerance. The success of this approach was demonstrated in several plants, where overexpression of the Arabidopsis gene AtNHX1 that encodes a vacuolar sodium/proton antiporter, resulted in higher plant salt tolerance. In an effort to engineer cotton for higher drought- and salt-tolerance, we created transgenic cotton plants expressing AtNHX1. These AtNHX1-expressing cotton plants generated more biomass and produced more fibers when grown in the presence of 200 mM NaCl in greenhouse conditions. Furthermore, the field-grown AtNHX1-expressing cotton plants produced more fibers with better quality, indicating that AtNHX1 can indeed be used for improving salt stress tolerance in cotton. However, the increased salt-tolerance is limited at around 200 mM NaCl, suggesting that the protons used for exchange of sodium ions may become limited at 200 mM NaCl condition, consequently a higher proton pump activity may be needed if higher salt-tolerance is expected. The Arabidopsis gene AVP1 encodes a proton pump, and overexpression of AVP1 generates higher proton electrochemical gradient across the vacuolar membrane that energizes secondary transporters including AtNHX1, leading to increased vacuolar solute concentration and therefore higher salt- and drought-tolerance in transgenic plants. A coupled expression of AtNHX1 and AVP1 would potentially confer higher tolerance against drought and salt in transgenic plants. Therefore creating another transgenic cotton line that expresses the Arabidopsis AVP1 gene is ongoing. The AVP1-expressing cotton will be crossed to AtNHX1-expressing cotton to obtain AtNHX1/AVP1-double expressing cotton plants in the near future. Updated information on our efforts will be reported at the meeting.