Cytogenetic study of onion (Allium cepa) by physical mapping of ESTs

D.V. Romanov, M.G. Divashuk, I.V. Kirov, L.I. Khrustaleva
Onion (Allium cepa L.) is an important part of human nutrition and also a rich source of healthy substances. The onion genome is still poorly studied due to its large size, high duplication level and heterozygosity. Physical mapping of genes is of great practical importance for onion breeding. To develop DNA probes for in situ hybridization we used expressed sequence tags (EST) from two onion EST libraries: from Native Plants, Inc., Salt Lake City, Utah, USA (prefix API) and from Plant Research International, Wageningen, The Netherlands (prefix PRI). The insert size of EST-clones was from 750 to 2600 bp. Tyramide-FISH technique was used to increase the detection sensitivity of the small target DNA sequences. Tyramide-FISH mapping of the EST clones revealed hybridization signals on different onion chromosomes at specific positions. It allows to distinguish individual chromosomes and to use these EST clones as cytogenetic markers. We demonstrated the efficacy of chromosomal in situ mapping of ESTs for the extremely large onion genome. We were able to visualize relatively small target DNA sequences on compacted onion metaphase chromosomes. The results of this work may assist sequence assembly of onion genome.
Romanov, D.V., Divashuk, M.G., Kirov, I.V. and Khrustaleva, L.I. (2021). Cytogenetic study of onion (Allium cepa) by physical mapping of ESTs. Acta Hortic. 1326, 173-180
DOI: 10.17660/ActaHortic.2021.1326.23
Allium cepa, Tyramide-FISH, chromosome, expressed sequence tag, cytogenetic marker

Acta Horticulturae