Inducing and identifying artificially-induced polyploidy in bananas

Abstract

In the present work, polyploidy was induced in the diploid banana varieties 'Malbut', 'Gold', 'Lidi', and 'Thong Dok Mak' through the use of colchicine and oryzalin, and that condition was identified through stomatal analysis, flow cytometry, and chromosome counts. Shoots produced in vitro were treated with colchicine at concentrations of 0, 2.5, 7.5 and 12.5 mM for 24 and 48 h, and with oryzalin at 0, 10, 30 and 50 mM for 4 and 7 days. Young leaves were scanned by electron microscopy to determine their stomatal areas (polar diameter × equatorial diameter) and numbers for polyploid identification by stomatal analysis. Polyploid identification by way of flow cytometry analysis used samples of young leaves that were crushed to release their nuclei, with subsequent staining with propidium iodide; ten thousand nuclei were analyzed for each sample. For cytogenetic analyses, root tips were pretreated with 0.002 M 8-HQ for 3 h, fixed in Carnoy solution for 24 h, subjected to conventional squashing techniques, and stained with 10% Giemsa. We identified four tetraploid plants and six mixoploids using these three identification techniques.