A simplified protocol for micropropagation of guayule (Parthenium argentatum gray)

A simple, efficient protocol for in vitro micropropagation of guayule is reported. Shoot cultures were maintained on MS (Murashige and Skoog, 1962) medium supplemented with 1.0 mg l−1 (4.4 μM) 6-benzylaminopurine and 0.025 mg l−1 (0.3 μM) α-naphthaleneacetic acid. Excised shoots were treated for 14–18 h with 100 mg l−1 (492.1 μM) indole-3-butyric acid in 0.5 x MS salts to induce rooting. The shoots were subsequently inserted into cellulose plugs which were packed in sterile, ventilated plastic culture vessels and moistened with 0.5 x MS medium without growth regulators. Use of cellulose plugs, liquid medium and ventilated culture vessels facilitated acclimation. Rooted shoots were transplanted into potting medium and acclimated to greenhouse conditions by covering with a cloche for 2 d, followed by daily watering for the first week.