Optimization of in vitro disinfection process and acclimatization of sugarcane (Saccharum spp. hybrid) var. MEX 69-290

Abstract

The phase of disinfection of sugar cane apices and the acclimatization phase are not always effective. The success of disinfection depends on the variety, the load of endophyte microorganisms, and the sensitivity to disinfectants, which cause tissue oxidation. While, in vitro rooted seedlings are using for acclimatization, where functional leaves and roots are poorly developed. Therefore, the aim of this work was to optimize the disinfection of sugar cane apices during their in vitro establishment and achieve acclimatization of rootless shoots directly from the multiplication phase. In the disinfection phase, shoot apices of variety MEX 69-290 were used, testing 12 treatments resulting from the combination of three disinfection methods (with NaClO, NPsAg, gentamicin), the presence or absence of coconut water, and two concentrations of plant growth regulators. In the acclimatization phase, rootless shoots generated directly from the multiplication phase were used, subjected to the interaction of applying or not applying indolebutyric acid at the base of shoots, presence or absence of mycorrhiza in the substrate, and application or non-application of 24-epibrassinolide. In the disinfection of sugar cane apices, adding gentamicin to the medium improved disinfection only for the first 14 days. However, the treatment with the highest levels of asepsis, survival, and morphogenic response at 14 and 63 days was NaClO at 3% for 15 min + NaClO at 0.06% for 5 min with BAP (1.68 mg L-1) + IAA (0.175 mg L-1) in the culture medium. It was possible to acclimatize 75% of the shoots directly from the multiplication stage by adding AIB auxin at the base of shoots, 1.5 g of mycorrhiza per planting hole, and two leaf applications of 1 mL of 0.0096 mg L-1 24-epibrassinolide.