Extreme QTL mapping of germination speed in Arabidopsis thaliana

Mol Ecol. 2016 Sep;25(17):4177-96. doi: 10.1111/mec.13768.


Seed germination is a key life history transition for annual plants and partly determines lifetime performance and fitness. Germination speed, the elapsed time for a nondormant seed to germinate, is a poorly understood trait important for plants' competitiveness and fitness in fluctuating environments. Germination speed varied by 30% among 18 Arabidopsis thaliana populations measured, and exhibited weak negative correlation with flowering time and seed weight, with significant genotype effect (P < 0.005). To dissect the genetic architecture of germination speed, we developed the extreme QTL (X-QTL) mapping method in A. thaliana. The method has been shown in yeast to increase QTL mapping power by integrating selective screening and bulk-segregant analysis in a very large mapping population. By pooled genotyping of top 5% of rapid germinants from ~100 000 F3 individuals, three X-QTL regions were identified on chromosomes 1, 3 and 4. All regions were confirmed as QTL regions by sequencing 192 rapid germinants from an independent F3 selection experiment. Positional overlaps were found between X-QTLs and previously identified seed, life history and fitness QTLs. Our method provides a rapid mapping platform in A. thaliana with potentially greater power. One can also relate identified X-QTLs to the A. thaliana physical map, facilitating candidate gene identification.

Keywords: bulk-segregant analysis; life history; quantitative genomics; seed ecology.

MeSH terms

  • Arabidopsis / genetics*
  • Arabidopsis / physiology
  • Chromosome Mapping / methods*
  • Genotype
  • Germination / genetics*
  • Phenotype
  • Quantitative Trait Loci*

Associated data

  • Dryad/10.5061/dryad.kt5nq