The Epicuticular Waxes on the Organs of Different Varieties of Banana (Musa Spp.) Differ in Form, Chemistry and Concentration

Abstract

The epicuticular waxes of leaves, bracts and fruits of 12 banana (Musa spp.) varieties were studied with respect to total wax concentration, chemical composition and ultrastructure.

Leaf wax production commenced at the time of leaf emergence and reached a maximum at leaf position 3 or 4, some 30-40 days after emergence. Field-grown leaves had 60% more wax (80-90 μg cm^-2) than glasshouse-grown leaves. Wax form varied with leaf maturity and large differences in form and concentration were observed between varieties with the acuminata genome (A) compared with those containing the balbisiana genome (B). The predominant chemical groups in leaf waxes were paraffins, primary alcohols and fatty acids, irrespective of genome.

Bracts were waxier (up to 238 μg cm^-2 and some differences in ultrastructure were associated with genomic make-up. Chemical groups were mostly esters and fatty acids.

Fruits were the most waxy of the organs studied (up to 942 μg cm^-2 ) , and differences in quantities of wax among genomic groups were observed. Fruit waxes were less distinctly structured than leaf or bract waxes and contained significant amounts of ketones and aldehydes, along with esters, fatty acids and primary alcohols.