Submitted to: Acta Horticulturae
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/1/2014
Publication Date: 12/11/2014
Citation: Fazio, G. 2014. Breeding apple rootstocks in the 21st century – what can we expect them to do to increase productivity in the orchard?. Acta Horticulturae. 1058:421-428.
Interpretive Summary: Rootstocks are the foundation of a healthy and productive orchard. As such, the choice of a rootstock can influence the productivity and profitability of an orchard in a very significant way. This overview describes how future apple rootstocks may be developed to increase productivity, disease resistance and sustainability of apple orchards. In this overview we identify certain rootstock component traits (nutrient uptake, gene expression modification in the scion and introduction of open scion canopies) and emerging technologies (high throughput genotyping and phenotyping) that show promise in the application of marker assisted breeding.
Technical Abstract: Rootstocks are the foundation of a healthy and productive orchard. As such, the choice of a rootstock can influence the productivity and profitability of an orchard in a very significant way. Rootstock performance is highly correlated with the genetic potential of such rootstock to provide anchorage, explore the soil profile, absorb and transfer nutrients to the scion, adapt to pedo-climatic conditions, tolerate extreme weather events, resist or cope with pathogens, propagate efficiently, and impart positive architectural properties to the scion – like vigor control and precocity. The inheritance and control of all these desirable characters is quite complex, making breeding quite challenging. Recent advances in genomic technologies are allowing more efficient, and informed ways of selecting new rootstocks during the breeding process. Furthermore, breaking down complex traits like tree vigor into component traits (hormonal transport, nutrient uptake and transport, root architecture, water use efficiency) and further characterization of the inheritance of these component traits can simplify the understanding of complex traits and improve the efficacy of the breeding process and its overall outcome. In the Geneva® breeding program, we have been studying root architecture, nutrient uptake and translocation, and inheritance of gene expression to better characterize breeding populations and select parents and seedlings for the next generation of apple rootstocks. We present an overview relating to these traits and how they are associated with good performance of released and elite stage apple rootstocks.