AOBPreview published online on October 8, 2009
Annals of Botany, doi:10.1093/aob/mcp253
Genetic analysis of potassium use efficiency in Brassica oleracea
1 Scottish Crop Research Institute, Invergowrie, Dundee DD2 5DA, UK
2 Warwick HRI, University of Warwick, Wellesbourne, Warwick CV35 9EF, UK
3 Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ, UK
4 Plant and Crop Sciences Division, University of Nottingham, Sutton Bonington Campus, Loughborough, Leicestershire LE12 5RD, UK
* For correspondence. E-mail philip.white{at}scri.ac.uk
Received: 7 July 2009 Returned for revision: 18 August 2009 Accepted: 10 September 2009
Background and Aims: Potassium (K) fertilizers are used in intensive and extensive agricultural systems to maximize production. However, there are both financial and environmental costs to K-fertilization. It is therefore important to optimize the efficiency with which K-fertilizers are used. Cultivating crops that acquire and/or utilize K more effectively can reduce the use of K-fertilizers. The aim of the present study was to determine the genetic factors affecting K utilization efficiency (KUtE), defined as the reciprocal of shoot K concentration (1/[K]shoot), and K acquisition efficiency (KUpE), defined as shoot K content, in Brassica oleracea.
Methods: Genetic variation in [K]shoot was estimated using a structured diversity foundation set (DFS) of 376 accessions and in 74 commercial genotypes grown in glasshouse and field experiments that included phosphorus (P) supply as a treatment factor. Chromosomal quantitative trait loci (QTL) associated with [K]shoot and KUpE were identified using a genetic mapping population grown in the glasshouse and field. Putative QTL were tested using recurrent backcross substitution lines in the glasshouse.
Key Results: More than two-fold variation in [K]shoot was observed among DFS accessions grown in the glasshouse, a significant proportion of which could be attributed to genetic factors. Several QTL associated with [K]shoot were identified, which, despite a significant correlation in [K]shoot among genotypes grown in the glasshouse and field, differed between these two environments. A QTL associated with [K]shoot in glasshouse-grown plants (chromosome C7 at 62·2 cM) was confirmed using substitution lines. This QTL corresponds to a segment of arabidopsis chromosome 4 containing genes encoding the K+ transporters AtKUP9, AtAKT2, AtKAT2 and AtTPK3.
Conclusions: There is sufficient genetic variation in B. oleracea to breed for both KUtE and KUpE. However, as QTL associated with these traits differ between glasshouse and field environments, marker-assisted breeding programmes must consider carefully the conditions under which the crop will be grown.
Key words: Arabidopsis, Brassica oleracea, genetics, potassium (K), potassium use efficiency (KUE), quantitative trait loci (QTL), shoot