Ploidy estimation and pre-selection of banana autotetraploids after in vitro polyploidy induction

ABSTRACT This study aimed to evaluate the efficiency of the parameters fresh leaf mass and stomatal density in the estimation of ploidy and pre-selection of putative banana autotetraploids. Young plants of the diploid cultivar Ouro (AA), previously subjected to in vitro polyploidization with the antimitotic amiprofos-methyl - APM (0, 10, 20, 30, 40, and 60 µM L-1) and colchicine (2.5 mM L-1) were evaluated for survival, height, number of leaves, pseudostem diameter, leaf disc fresh mass, and stomatal density. Ploidy was determined by flow cytometry in a random sample of 200 plants to find the relationship between the genomic content and the analyzed variables. Spearman’s correlation analysis showed a strong correlation (0.84**) between leaf disc fresh mass and tetraploid plants, as well as an absence of significant correlation between stomatal density and ploidy levels. Thus, the pre-selection of plants was carried out using a reference value of leaf disc fresh mass and resulted in 688 plants pre-selected as putative tetraploids. Among them, 318 were confirmed as tetraploids, 291 as diploids, and 79 as mixoploids after flow cytometry analysis. The pre-selection efficiency was 46.2% of tetraploid plants from the total pre-selected. The results indicate that the use of leaf disc fresh mass is a simple, practical, and promising method to estimate ploidy when a high number of plants is obtained in in vitro banana polyploidization studies, reducing the total number of plants to have confirmed ploidy.