Effects of plant growth regulators on callugenesis, browning and plantlet regeneration in leaf culture of sugarcane and in vitro production of sugarcane mutant resistant to glyphosate herbicide

Weeds are a limiting factor in sugarcane cultivation and able to reduce its yield during the growing season. In this study, first, the effect of 2,4-D plant growth regulators at 6 levels, kinetin (Kin) at two levels and 6-benzyl aminopurine (BAP) at two levels on callus induction, organogenesis and browning of leaf explants of sugarcane (Saccharum officinarum L.) cultivar 'CP69-1062' was investigated. The results showed that the highest callus induction was observed in MS medium (Murashige and Skoog) containing 2 mg.  2, 4-D with 2 mg.  BAP.  Explant browning was the highest on MS medium without plant growth regulators and MS medium containing 1 mg.  2,4-D and 2 mg.  BAP. Also in medium with 2 mg.  BAP, direct organogenesis was achieved. In the second experiment, calli produced in MS culture medium containing 16 mg.  2,4-D, 1 mg.  Kin and 2 mg.  BAP were transferred to regeneration medium containing different concentrations of glyphosate herbicide. The results showed that in regeneration medium without glyphosate, plantlets were induced, but calli affected by the glyphosate herbicide were not able to produce plantlets. In another experiment, calli produced in the optimal culture medium were immersed in the liquid culture medium containing 4 different levels of ethyl methane sulfonate (EMS) for 0, 3, 6, 12, 24, and 48 hours to cause mutations. In an EMS-free control medium, calli were able to produce plantlets at all times, but with increasing concentration and duration of treatment with EMS, plant regeneration was decreased. Then, to select resistant plantlets, glyphosate herbicide was sprayed on them with a concentration of 4%. Of the 20 plants treated with glyphosate, only 1 showed resistance to herbicide.