Caracterização morfoagronômica e citogenética de bananeiras autotetraploides obtidas mediante duplicação de cromossomos

Abstract

In vitro duplication of the chromosome number is an important tool to complement conventional activities in banana genetic breeding by autotetraploid production which to be used in crosses with improved diploids for developing secondary triploids. The present work aim to characterize morphologically ‘Ouro’ and ‘Lidi’ plants bananas from chromosome doubling and investigate the meiotic behavior and fertility of pollen grains of autotetraploids of ‘Lidi’. The autotetraploids from ‘Lidi’ were affected by allelic dosage, with significant increase in interesting traits for breeding when compared to their original diploids, including resistance to yellow Sigatoka. For the cytogenetic characterization the abnormalities varied from 23,9% to 35,0% in the meiocytes of the original Lidi diploids and of 31,0% to 47,2% in their autotetraploids with greater concentration of abnormalities in metaphase I. The most common abnormalities in all genotypes analyzed with different ploidy levels were those related to early rise and irregular segregation of chromosomes leading to the formation of unbalanced gametes. Although the Lidi autotetraploids presented meiotic abnormalities, they showed good pollen fertility and therefore may be used as male parents. Female fertility was also detected since plants produced seeds which varied from one to three per plant, indicating that may be used as female parents.