Cultivo in vitro de anteras de três variedades botânicas de meloeiro

Abstract

In melon (Cucumis melo L.), a vegetable of great economic importance, the dihaploidization technique is an effective tool to obtain 100% homozygous line in only one generation. Therefore, the objective of this work was to obtain melon haploid plants by in vitro anthers culture of the varieties: cantalupensis, reticulatus and inodorus. The explants were anthers excised of pre-anthesis male flowers. The assay was divided into two experiments. In experiment 1, step of calogenesis: four culture media were used: (1) MS without growth regulators; (2) MS + 1.0 μM BAP + 2.0 μM 2,4-D; (3) MS + 0.88 μM BAP + 3.22 μM NAA; and (4) MS + 4.44 μM BAP + 2.26 μM 2,4-D + 4.64 μM KIN. The experimental design was completely randomized, in a 3x4 factorial scheme, with three botanical varieties and four culture media, with 25 replicates (anther)/ treatment / variety. Step of shoot regeneration: callus was transferred to MS medium + 0.5 μM NAA + 13.32 μM BAP. The experimental design was completely randomized, in a 3x4 factorial scheme, with three botanical varieties and calli from four culture media, with 25 replicates (anther)/treatment /variety. The data were submitted to analysis of variance and means, compared by the Tukey test at 5% probability. For data that did not meet normality, Kruskal-Wallis test was used. In experiment 2, step of calogenesis: MS + 1.0 μM BAP + 2.0 μM 2,4-D medium was used with two sucrose concentrations (30 and 120 g.L-1). The cultures remained at 4 ° C in the dark for two days. The experimental design was completely randomized, in a 3x2x2 factorial scheme, with three botanical varieties, two sucrose concentrations and two residence times in the culture medium (14 and 28 days), with 50 replicates (anthers)/treatment /variety. Step of shoot regeneration: callus was transferred to MS medium + 2.22μM BAP with 30 and 120 g.L-1 sucrose. The data were submitted to univariate analysis by Scott-Knott and the means compared at the 5% level of significance. The cultures remained at 25 ± 1 oC, 16 hours light, during the two experiments. In experiment 1, there was no difference for callus formation between the varieties and explant contamination of only 2%. Media 2 and 4 were more effective, producing calli in 100 and 97.73% of the anthers, respectively. There was no shoot regeneration in any of the varieties using MS + 0.5 μM NAA + 13.32 μM BAP. In experiment 2, calli formation occurred in all anthers inoculated in the induction culture medium. Cantalupensis was more efficient in most of the evaluated factors. There was no shoot regeneration in MS medium + 2.22 μM of BAP. The protocol used was not efficient for obtaining haploid plants of the three varieties of melon studied.