Engineering Cotton for Increased Drought/Salt Tolerance and Improved Fertilizer Use Efficiency

The United States is the third largest cotton producer in the world and Texas is the No. 1 cotton producer in the US responsible for ~30% of nations’ cotton production. In Texas High Plains, drought and saline soils are the major limiting factors that reduce quantity and quality of cotton fibers. Also, the excessive use of fertilizers results in salt accumulation in cotton lands. This is in part due to severe drought conditions in dryland agricultural systems. In some instances, lands are no longer suitable for cotton production. This research uses Agrobacterium-mediated plant transformation to co-overexpress PP2A-C5 and AVP1 in cotton in order to generate a cotton variety that can outperform conventional cotton varieties under dryland and irrigated agricultural systems. PP2A-C5 is the catalytic subunit 5 of Arabidopsis protein phosphatase 2A. Arabidopsis plants overexpressing PP2A-C5 are more tolerant to high concentrations of NaCl, KCl, and KNO₃. These plants also absorb nitrate and potassium fertilizers more efficiently.  PP2A-C5 mediated multi-salt tolerance is possibly achieved via positive regulation of chloride channel proteins localized to the vacuolar membrane, e.g. CLCa and CLCc, which import NO₃^- and Cl^- ions into the vacuole, respectively, at expense of protons. The AVP1 gene encodes a vacuolar membrane-bound H⁺ pyrophosphatase in Arabidopsis and overexpression of AVP1 increases H⁺ accumulation in the vacuole, thereby activating secondary transporters such as Na⁺/H⁺antiporters, chloride channel proteins, K⁺ and inorganic PO₄^3- transporters. As a result, the osmotic potential inside the vacuole is increased making the transgenic plants more drought- and salt-tolerant. These plants will be more efficient in NPK absorption as well. Therefore, these transgenic plants will be expected to outperform AVP1-overexpressing and PP2A-C5-overexpressing cotton plants in terms of drought and salinity tolerance and fertilizer use efficiency.

The results of this project will be presented in the conference.