ARS | Publication request: Breeding broccoli adapted to high temperature environments

Submitted to: Plant Physiology
Publication Type: Abstract Only
Publication Acceptance Date: July 1, 2011
Publication Date: August 6, 2012
Citation: Farnham, M.W., Bjorkman, T. 2012. Breeding broccoli adapted to high temperature environments. Plant Physiology. P09015.

Technical Abstract: A breeding program to select broccoli (Brassica oleracea L. Italica Group) for adaptation to summer environments has been conducted at the U.S. Vegetable Laboratory (USVL) in Charleston, South Carolina, for almost two decades. This effort provides a case study of a concerted effort to breed polygenic tolerance to an abiotic stress. This program was initiated using a population with phenotypes that initiate and develop large inflorescences under summer conditions. It employs a conventional pedigree breeding approach in which different inbreds are crossed to one another to form hybrids that are subsequently selfed to create segregating populations. Several rounds of selection and recombination have resulted in inbred lines increasingly adapted to hot and humid summer conditions of the Southeast. These USVL summer broccoli lines appear to be distinct from other available broccoli germplasm, most of which exhibit developmental dysfunction for head formation or do not form heads at all in the hot evaluation and selection environment. Field studies conducted at different locations and times of the year indicate that USVL hybrids, made by crossing select inbreds from the program, are adapted to summer conditions of the East, performing very consistently regardless of the temperature conditions they are grown in. Recently, a doubled haploid population derived from a heat tolerant by heat susceptible cross was developed to study inheritance of the tolerance trait. Genetic mapping and detailed phenotyping of this population will identify QTLs associated with the tolerance.