Journal of the American Society for Horticultural Science 131:
667-673
Inflorescence Identity Gene Alleles Are Poor Predictors of
Inflorescence Type in Broccoli and Cauliflower
Joanne A. Labate, Larry D. Robertson, Angela M. Baldo, and
Thomas Björkman
USDA-ARS Plant Genetic Resources Unit, Geneva, NY 14456
Department of Horticultural Sciences, New York State Agricultural
Experiment
Station, Cornell University, Geneva, NY 14456
ABSTRACT Broccoli (Brassica
oleracea L. var. italica Plenck) and
cauliflower (B. oleracea var. botrytis
DC) are closely related botanical varieties. The underlying genetic
bases of their phenotypic differences from each other are not well
understood. A molecular genetic marker enabling B. oleracea
germplasm curators and breeders to predict phenotype from seeds or
seedlings would be a valuable tool. Mutant alleles at flower
developmental pathway loci BoAP1-a, BoCAL-a,
and glucosinolate biosynthetic pathway locus BoGSL-ELONG
have been reported to be associated with a cauliflower phenotype. We
surveyed mutant alleles at these three loci in a genetically diverse
sample of broccoli and cauliflower accessions from the U.S. Department
of Agriculture, Agricultural Research Service (USDA-ARS) Plant Genetic
Resources Unit (PGRU) and the University of Warwick, Genetic Resources
Unit of Warwick HRI (HRI). Phenotypic and genotypic data were collected
for multiple plants per accession during two field seasons. Simple
genetic models assuming dominance or codominance of alleles were
analyzed. Goodness-of-fit tests rejected the null model that the mutant
genotype was associated with a cauliflower phenotype. A correlation
analysis showed that BoAP1-a and BoCAL-a
alleles or loci
were significantly correlated with phenotype but the fraction of
variation explained was low, 4.4% to 6.3%. Adding BoGSL-ELONG
to the analysis improved predictive power using the linear regression
procedure, Maximum R-square Improvement (max R2).
In the best three-variable model, only 24.8% of observed phenotypic
variation was explained. Because tested genetic models did not hold
robustly for the surveyed accessions, it is likely that there are
multiple genetic mechanisms that influence whether the phenotype is
broccoli or cauliflower. Our results in commercial cultivars indicate
that other genetic mechanisms are more important in determining the
horticultural type than are BoAP1-a and BoCAL-a.
JASHS
website
PDF
Version of whole article (7MB)
Back
to publication list