A trait-led approach which exploits natural variation in
seed vigour to enhance crop establishment.
K. Morris, K.C. Dent, J. Lynn. G.C. Barker, H.A. Clay, E.C. Howell† and W.E. Finch-Savage
Warwick HRI, University of Warwick, Wellesbourne, Warwick, CV35 9EF, UK
† School of Biosciences. University of Birmingham
Contact: karl.morris@warwick.ac.uk; bill.finch-savage@warwick.ac.uk
1.
1. Previous work has focussed on rate of germination (ROG) QTL on linkage groups BO1
(ROG1) and BO3 (ROG2) (Bettey et al. 2000). Informative lines from a backcross
substitution library (Rae et al. 1999) having GDDH33 (fast germinating parent) introgressed
chromosomal tracts in the A12DHd (slow germinating parent) background were employed to
fine map ROG1 and ROG2. A substitution line (SL101) was identified that had a small
introgressed region (c. 1 cM) within ROG1 that accounted for much of the difference in
germination rate between the parent lines.
Germination (%)
The ability of seeds to establish seedlings in a predictable manner under a range of conditions
(vigour) has a direct contribution to the economic success of commercial crops, and should therefore
be considered in crop improvement. Crop establishment studies show that rapid germination,
rapid pre-emergence root growth and upward shoot growth in strong soil are essential to effective
seedling establishment.
100
75
Low vigour
25
0
0
2
BO3
BO1
cM
cM
93.2
pN121E2
95.8
pO12E2
99.3
pW216J1
104.3
AC-CACJ01
ROG1
107.1
107.7
108.6
pO70E1
pN13E1
pR85E1
4
6
Time (d)
8
High Vigour
10
Low Vigour
GD33
Parent
2.
SL101
SL122
SL167
A12
GD33
High vigour
50
SL101
SL167
SL122
Substitution lines
A12
Parent
A. thaliana Chr 3
2. Co-linearity between ROG1, ROG2 and the top of Arabidopsis chromosome 3 was
demonstrated with a limited number of RFLP probes. This co-linearity has now been confirmed
using a range of Arabidopsis probes. A QTL for germination rate has been identified on the top
of Arabidopsis chromosome 3 by another group (Clerkx et al. 2004). These germination rate
QTL on both B. oleracea and A. thaliana co-locate with a number of stress specific germination
traits suggesting them to be important general QTL influencing germination.
ROG2
69.3
pR85E2
72.1
pW172E2
76.1
78.9
78.9
80.3
pO12E1
AC-CACE01
pR116E2N
AA-CATJ04
AIM: To identify candidate genes for ROG1
3. A BAC tiling path that spans the ROG1 locus is nearing completion. Key BACs
have been confirmed in this region by fluorescent in situ hybridisation and polymorphic
markers have been developed to resolve the QTL.
3.
4. 33 recombinant inbred lines were generated by back crossing SL101 to the recurrent
A12DHd parent. The molecular markers were used to assign parental genotype scores
which were used with the screen for rate of germination assay. Statistical analysis of the
germination data set has placed the ROG1 QTL between two adjacent molecular
markers. The linkage of these markers to the ROG1 QTL was observed in two different
seed production runs, under different environmental conditions.
5. Sequence analysis of a BAC that spans the significant markers that delineate the ROG1 QTL has identified 13 putativeBrassica
oleracea gene models. This subset of genes are now the focus of our current work.
CURRENT WORK
• Screen Arabidopsis KO lines of candidate genes for
germination phenotypes.
• QRT-PCR for candidate genes from a seed developmental
series.
• Transform candidate genes (including native promoters) from
A12DHd and GDDH33 parents into Arabidopsis for functional
germination testing.
Bettey, M. et al. 2000. New Phytologist 148, 277-286
Clerkx, EJM. et al. 2004. Plant Physiology 135, 432-443
Rae, AM. et al. 1999. Heredity 83, 586-596
• QRT-PCR for ABA and giberellic acid metabolic genes
from same developmental series.
• Screen a GDDH33 cosmid library in order to carry out
comparative genome analysis
Acknowledgments: We thank M. Bettey, J. Stephen and G. King, earlier work on this
project was funded by DEFRA. Work in progress is funded by a BBSRC Crop Science
Initiative Industrial Partnership Award (Syngenta Seeds B.V.)