SWAT - Scalable W(R)ubber through Advanced Technology

Opportunity: Guayule, a US native plant, is the only alternate rubber crop with an established, mechanized, agronomic system. Problem: Low rubber yields and lack of effective resin and bagasse coproduct valorization, have prevented widespread adoption by American farmers and processors. Rubber is only made when the cytoplasmic monomer pool (isopentenyl-pyrophosphate; IPP) is larger than that required for cell growth and development, and this pool must be increased to improve rubber yield. Previous biotechnological efforts to manipulate IPP pools initially increased rubber production but plants could not maintain improved rubber yield past their seedling stage, likely caused by accumulation of toxic pyrophosphate (PP) byproducts and a pH shift in cells with increased rubber synthesis (a PP and a proton is released with every monomer added to the growing polymer). Solution: To overcome this key limitation, we have generated a series of transgenic guayule lines expressing gene stacks encoding enzymes synthesizing rubber precursors, as well as transport proteins capable of removing toxic protons and PP from the cytosol of rubber-producing cells. Benefit/Outcome: These plants will be metabolically profiled and screened for rubber production, with lines producing 150+% of baseline, serving as the foundation for an enhanced rubber production system.