ON THE COVER: Onion (Allium cepa) exhibits wide variation in bulb fructan content, and the Frc locus on chromosome 8 conditions much of this variation. In this issue, biochemical analysis of A. fistulosum-shallot (A. cepa Aggregatum group) alien monosomic addition lines (AALs) (Yaguchi et al. pp. 730–739) demonstrates that the sucrose and fructan levels and sucrose phosphate synthase (SPS) activity in the alien monosomic addition of chromosome 8 in A. fistulosum are significantly changed. Genetic analysis shows that SPS loci are assigned to chromosome 8 using AALs and onion linkage mapping populations. The concordance between chromosome 8 localization of SPS and elevated leaf sucrose levels conditioned by high fructan alleles at the Frc locus in bulb onion or AALs suggest that the Frc locus may condition variation in SPS activity.
The cover photo shows plants of onion and a complete set of AALs and somatic metaphase chromosomes of a certain AAL.
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