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Abstract
Lachrymatory factor synthase (LFS) catalyzes the formation of lachrymatory factor, one of the most distinctive traits of bulb onion (Allium cepa L.). Therefore, we used LFS as a model for a functional gene in a huge genome, and we examined the chromosomal organization of LFS in A. cepa by multiple approaches. The first-level analysis completed the chromosomal assignment of LFS gene to chromosome 5 of A. cepa via the use of a complete set of A. fistulosum–shallot (A. cepa L. Aggregatum group) monosomic addition lines. Subsequent use of an F2 mapping population from the interspecific cross A. cepa × A. roylei confirmed the assignment of an LFS locus to this chromosome. Sequence comparison of two BAC clones bearing LFS genes, LFS amplicons from diverse germplasm, and expressed sequences from a doubled haploid line revealed variation consistent with duplicated LFS genes. Furthermore, the BAC-FISH study using the two BAC clones as a probe showed that LFS genes are localized in the proximal region of the long arm of the chromosome. These results suggested that LFS in A. cepa is transcribed from at least two loci and that they are localized on chromosome 5.
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1 United Graduate School of Agricultural Science, Tottori University, Tottori 680-8553, Japan; Somatech Center, House Foods Corporation, Yotsukaido, Chiba 284-0033, Japan
2 New Zealand Institute for Plant and Food Research Limited, Christchurch 8140, New Zealand
3 Russian State Agrarian University, Moscow Timiryazev Agricultural Academy, Moscow 127550, Russia
4 Somatech Center, House Foods Corporation, Yotsukaido, Chiba 284-0033, Japan
5 Division of Natural Science, Osaka Kyoiku University, Kashiwara 582-8582, Japan
6 United Graduate School of Agricultural Science, Tottori University, Tottori 680-8553, Japan; Faculty of Agriculture, Yamaguchi University, Yamaguchi 753-8515, Japan
7 United Graduate School of Agricultural Science, Tottori University, Tottori 680-8553, Japan; United Graduate School of Agricultural Science, Tottori University, Tottori 680-8553, Japan; Faculty of Agriculture, Yamaguchi University, Yamaguchi 753-8515, Japan