Linkage mapping and QTL analysis of flowering time in faba bean

Abstract

Flowering time marks the transition from vegetative to reproductive growth and is key for optimal yield in any crop. The molecular mechanisms controlling this trait have been extensively studied in model plants such as Arabidopsis thaliana and rice. While knowledge on the molecular regulation of this trait is rapidly increasing in sequenced galegoid legume crops, understanding in faba bean remains limited. Here we exploited translational genomics from model legume crops to identify and fine map QTLs linked to flowering time in faba bean. Among the 31 candidate genes relevant for flowering control in A. thaliana and Cicer arietinum assayed, 25 could be mapped in a segregating faba bean RIL population. While most of the genes showed conserved synteny among related legume species, none of them co-localized with the 9 significant QTL regions identified. The FT gene, previously implicated in the control of flowering time in numerous members of the temperate legume clade, mapped close to the most relevant stable and conserved QTL in chromosome V. Interestingly, QTL analysis suggests an important role of epigenetic modifications in faba bean flowering control. The new QTLs and candidate genes assayed here provide a robust framework for further genetic studies and will contribute to the elucidation of the molecular mechanisms controlling this trait.

Figure 1

Schematic model of the genetic pathway of flowering time control by the photoperiod. The central circle represents the circadian clock. Modified from Mouradov et al. (2002).

Figure 2

Linkage map and QTLs for flowering time traits detected in the Vf6 × Vf27 RIL population. QTL locations are represented with bars (2-LOD interval) and boxes (1-LOD interval). Candidate gene markers included in the map are highlighted in red. DF1: days to first flower, DF50: days to 50% of flowering, FL: flowering length. No significant QTLs were identified with *.