Induction of tetraploidity with antimicrotubule agents in oriental melon (Cucumis melo var. Makuwa)

Abstract

Polyploidy induction is an important method for the innovation of germplasm resources because polyploid plants have superior characteristics to diploid ones. In this paper, oriental melon (Cucumis melovar. makuwa) tetraploids were induced by treating the apical meristem of seedlings with oryzalin, amiprophos-methyl (APM) and colchicine. The results showed that each of these three antimicrotubule agents could induce the formation of tetraploid oriental melon, but oryzalin and APM showed higher efficiencies of tetraploid induction. The efficiencies of tetraploid induction were highest (14.44%) when treated with 80 µmol·L−1APM for 6 days. Stomata characteristics were used to screen the treated plants for changes in ploid levels preliminarily. Subsequently, the changes in ploid levels were further confirmed by flow-cytometric analysis and chromosome counts of root tip cells. The comparison between diploids and tetraploids in fruit characteristics, reproductive characteristics, and postharvest storage qualities showed that the fruit of tetraploids had thicker flesh, higher total soluble solid (TSS) content and lower fruit shape index than diploids. The pollen grains of tetraploids were larger but showed lower vitality. In addition, a higher percentage of embryo-deficient seeds contributed to lower fertility. During postharvest storage, the fruit of tetraploids softened faster, had higher TSS content and lower respiration rate.