We examined the genetic determinants of vigour control and precocity conferred on a pear scion by Pyrus rootstocks, for the purpose of enabling breeders to develop new pear rootstocks with improved vigour and floral precocity. A segregating population of 450 F1 rootstocks from a P. communis cross between ‘Old Home’ and ‘Louise Bonne de Jersey’ (OHxLBJ), grafted with ‘Doyenne du Comice’ scions, was comprehensively phenotyped for traits related to tree architecture and flowering, and the data modelled in order to describe the growth of the scions. Genotyping was performed using the apple and pear Infinium® II 9K SNP array. A high density SNP-based genetic map was constructed using 546 polymorphic pear and 99 apple markers. QTLs relating to vigour control and precocity were detected on LG5 and LG6 of ‘Old Home’. The LG5 QTL is orthologous to the Dw1 locus from ‘Malling 9’ apple rootstock (Rusholme Pilcher et al. 2008). Analysing the syntenic region linked to this QTL in the P. communis (‘Bartlett’), Malus x domestica (‘Golden Delicious’) and Prunus persica reference genomes should lead to the identification of candidate genes for vigour control in both pear and apple.
