Cloning of the ω-secalin gene family in a wheat 1BL/1RS translocation line using BAC clone sequencing|
Li, Meng Jun; Li, Ya Qing; Zhang, Nan & Shi, Zhan Liang
Background: Wheat 1BL/1RS translocation lines are planted around the world for their disease resistance and
high yield. Most of them are poor in bread making, which is partially caused by ω-secalins that are encoded by
the ω-secalin gene family, which is located on the short arm of rye chromosome 1R (1RS). However,
information on the structure and evolution of the ω-secalin gene family is still limited.
Results: We first generated a physicalmap of the ω-secalin gene family covering 195 kb of the Sec-1 locus based
on sequencing three bacterial artificial chromosome (BAC) clones of the 1BL/1RS translocation wheat cultivar
Shimai 15. A BAC contig was constructed spanning 168 kb of the Sec-1 locus on 1RS. Twelve ω-secalin genes
were arranged in a head-to-tail fashion, separated by 8.2–21.6 kb spacers on the contig, whereas six other
ω-secalin genes were arranged head-to-tail, separated by 8.2–8.4 kb of spacers on clone BAC125. The 18
ω-secalin genes can be classified into six types among which eight ω-secalin genes were expressed during
seed development. The ω-secalin genes with the 1074-bp open reading frame (ORF) represented the main
population. Except for two pseudogenes, the N-terminal of the ω-secalin gene was conserved, whereas
variations in the C-terminal led to a change in ORF length. The spacers can be sorted into two classes. Class-1
spacers contained conserved and non-conservative sequences.
Conclusion: The ω-secalin gene family consisted of at least 18 members in the 1BL/1RS translocation line cv.
Shimai 15. Eight ω-secalin genes were expressed during seed development. Eighteen members may originate
from a progenitor with a 1,074-bp ORF. The spacers differed in length and sequence conservation.
Bacterial artificial chromosome (BAC); Wheat; ω-Secalin; 1BL/1RS translocation line