Pollen viabilities and gene expression profiles across Musa genomes

Banana (Musa spp.) is a major global economic fruit crop. However, cross-pollination from other Musa 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 Musa genomes (AA, BB, AAA, BBB, AAB, ABB and ABBB). Twenty-three Musa 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 TPD1A and MYB80 genes were highly expressed in triploid Musa genomes but the PTC1 gene showed down-regulated expression, resulting in non-viable pollen. Pollen viability, pollen germination and pollen development-related genes differed across Musa cultivars. This knowledge will be useful for the selection of male parents for Musa cross-breeding programs. Pollen viability should also be considered when planning Musa production to avoid seeded fruit.

Assessment of the processing conditions which make the Ambrosia seeds non-viable

The European Commission requested EFSA to provide an assessment of the processing conditions which make Ambrosia seeds non-viable in feed materials and compound feed. This assessment also includes information on a reliable procedure to verify the non-viability of the seeds. Ambrosia seeds are known contaminants in feed with maximum levels set in the Directive 2002/32/EC. The manufacturing processes and processing conditions applied to the feed may affect the viability of the Ambrosia seeds. Therefore, the CONTAM Panel compared these conditions with conditions that have been shown to be sufficient to render Ambrosia seeds non-viable. The Panel concluded with a certainty of 99-100% that solvent extraction and toasting of oilseed meals at temperatures of 120°C with steam injection for 10 min or more will make Ambrosia seeds non-viable. Since milling/grinding feed materials for compound feed of piglets, aquatic species and non-food producing animals would not allow particles of sizes ≥1 mm (the minimum size of viable Ambrosia seeds) passing the grinding process it was considered very likely (with ≥ 90% certainty) that these feeds will not contain viable Ambrosia seeds. In poultry, pig, and possibly cattle feed, particle sizes are ≥ 1 mm and therefore Ambrosia seeds could likely (66-90% certainty) survive the grinding process. Starch and gluten either from corn or wheat wet milling would not contain Ambrosia seeds with 99-100% certainty. Finally, ensiling fresh forages contaminated with A. artemisiifolia seeds for more than 3 months is very likely to render all seeds non-viable. The Panel concluded that a combination of the germination test and a subsequent triphenyl-tetrazolium-chloride (TTC) test will very likely (with ≥ 90% certainty) verify the non-viability of Ambrosia seeds. The Panel recommends that data on the presence of viable Ambrosia seeds before and after the different feed production processes should be generated.