ISHS Acta Horticulturae 1110: XXIX International Horticultural Congress on Horticulture: Sustaining Lives, Livelihoods and Landscapes (IHC2014): International Symposium on Molecular Biology in Horticulture
Molecular genetics analysis of onion (Allium cepa L.) adaptive physiology of bulb |
| Authors: | J. McCallum, S. Baldwin, S. Thomson, M. Pither-Joyce, F. Kenel, R. Lee, J.S. Khosa, R. Macknight |
| Keywords: | genomics, mapping, photoperiod, vernalisation, flowering |
| DOI: | 10.17660/ActaHortic.2016.1110.11 |
| Abstract:
Bulb onion and shallot (Allium cepa L.) have been adapted for production from equatorial to high latitudes regions through selection over about 5000 years since domestication. Because adaptation is a major determinant of productivity and a barrier to plant breeding, we are using molecular and physiological approaches to identify and map genes and genome regions associated with bulb and flower formation. Mining of transcriptome resources permitted the identification and functional characterisation of many conserved candidates genes of regulatory pathways, most notably the FT-like family. Gene expression studies and over-expression in experimental transgenic plants confirmed that transition to bulbing in long-day onions is associated with reduction in expression of AcFT4 which represses, and increase in AcFT1 which promotes bulbing. Another family member, AcFT2 is expressed in basal shoot meristems of bulb following cold treatment. Resequencing candidate genes in a sample of LD and SD germplasm enabled preliminary population genetic analyses and location on the onion genetic map. QTL analysis located a major gene conditioning bolting on chromosome 1 which we denote AcBlt1. We describe ongoing efforts to resolve key adaptive genes by genomic and physiological analysis of diverse germplasm. | |
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