Pollen viabilities and gene expression profiles across genomes.

Banana ( spp.) is a major global economic fruit crop. However, cross-pollination from other cultivars grown in nearby plantations results in seeded fruit that exceeds market demand. This study investigated pollen viability and germination and examined the expression profiles of pollen development-related genes across seven genomes (AA, BB, AAA, BBB, AAB, ABB and ABBB). Twenty-three cultivars were assessed for pollen viability using lacto-aceto-orcein and triphenyltetrazolium chloride staining methods. Results revealed that pollen viability obtained from both methods was significantly different among all the studied cultivars. Cultivars carrying BB (diploid) genomes had higher viability percentages than AA (diploid), AAA, BBB, AAB and ABB (triploid) and ABBB (tetraploid) genomes. Germination of the studied cultivars was also investigated on pollen culture medium, with results showing significant differences between the pollen of each cultivar. The best germinating cultivar was TKM (11.0 %), carrying BB genome. Expression profiles of pollen development-related genes by RT-qPCR indicated that both and genes were highly expressed in triploid genomes but the gene showed down-regulated expression, resulting in non-viable pollen. Pollen viability, pollen germination and pollen development-related genes differed across cultivars. This knowledge will be useful for the selection of male parents for cross-breeding programs. Pollen viability should also be considered when planning production to avoid seeded fruit.