Phenotyping an F2 population in cabbage (Brassica oleracea)

Man with cabbage Bush

' to look for genomic regions associated to a number of life history traits'

Background and context

Why are there so many phenotypic differences between woody and herbaceous species? To this day, scientists have failed to provide satisfying answers. We have crossed a tall, woody, late flowering cabbage accession (Jersey kale) with a small, rapid flowering cabbage accession (TO1000) and obtained 200 F2 accessions in tissue culture (Fig. 1), allowing multiple experiments of the same genotype over time. Our objective is to find genomic regions associated with the phenotypic differences observed in the F2 generation (Quantitative Trait Loci experiment). A number of phenotypic differences that interests us are woodiness, drought stress resistance, flowering time, developmental speed, stem elongation, ageing, and plant herbivory.

CabbageCabbage
Fig. 1. Left: in-tissue culture of three accessions: TO1000, one of the F1 accessions, and the Jersey kale parent. Right: the same three accessions in mature state.

Objectives and goals

The major objective of this BSc-MSc project is to find genomic regions (QTLs) that can be linked with differences in woodiness, flowering time and drought stress resistance using an existing F2 population of Brassica oleracea based on a combined phenotype-genotype approach. The project wants to investigate if particular QTLs are governing different traits and in addition pinpoint candidate genes.

Material, tasks and approach

The project will use an existing plant tissue culture of Brassica oleracea to generate clones (ca 3 individuals per genotype) from the F2 population in which various life form traits have segregated due to the huge phenotypic differences between the parental lines. To measure flowering time, plants will be grown in a climate room and the days until flowering is measured. A number of drought stress measurements will be performed as well (e.g. detection of ROS/H2O2 by DAB staining, measure relative chlorophyll content and PS II efficiency). Stem anatomical observations will be performed at Naturalis Biodiversity Center. The samples will be taken from 1-2 individuals per F2 genotype. For light microscopy, the woody stems will be cut in transverse sections of 20 μm thickness using a sliding microtome and the herbaceous stems will be first embedded in plastic according to standard protocols.

Requirements

Interest in phenotype-genotype interaction is desired. Background in QTL analysis is ideal.

Supervisor and contacts

Prof. Peter Klinkhamer (IBL, Leiden Univ.)
Dr. Klaas Vrieling (IBL, Leiden Univ.)
Dr. Frederic Lens (Naturalis Biodiversity Center)
Dr. Rutger Vos (Naturalis Biodiversity Center)

Period and duration

Ca. 6 months, project can start directly. 

Study and level

BSc or MSc