Our HRC transformation protocol uses specific, identifiable, callus
tissues and offers high transformation efficiency (∼48%). This
method is independent of light intensity, and avoids browning and
slow growth after Agrobacterium infection, which commonly occur
in the leaf strip transformation method (Dong et al., 2006). This
alternative, higher transformation efficiency method should help in
rapid improvement of guayule for higher latex production following
metabolic engineering (Kumar et al., 2012). This method also
may enable improved transformation rates in other recalcitrant
plant species.