Rapid cycling breeding of tree species

Authors: Callahan, Ann; Dardick, Christopher - Chris; SCORZA, RALPH - Retired ARS Employee

Submitted to: World Congress on In Vitro Biology
Publication Type: Abstract Only
Publication Acceptance Date: 6/6/2020
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: The genetic improvement of tree species has been a perennial challenge to the breeding community due in large part to the long generation cycles of most fruit, forest, and ornamental tree species. Breeding for disease and insect resistance, improved production characteristics, and more recently, adaptation to a climate change must be accelerated in order to foster the development of productive orchards and sustainable forest systems. To meet these challenges the development and release of new improved varieties is more vital than ever. Yet, tree breeding remains a slow and costly process often taking multiple breeders’ lifetimes to produce trees with significant genetic improvements. Much research has focused on marker assisted selection, sequencing for candidate gene identification, and genetic engineering as means to advance tree fruit breeding. However, these strategies remain limited by inherently slow generation cycles. Transgenic plants overexpressing Flowering Locus T (FT) and other flowering regulatory genes have been shown to express significantly shorter juvenility periods, typically one year or less. We have used these modified plants to develop rapid cycle breeding programs in apple and plum that enable trait introgression in a few years rather than a few decades. While this breeding system leverages genetically engineered plants to accelerate breeding, the output is conventional cultivars as the ectopically expressed flowering gene can be selected against to yield non-transgenic progeny that in the US do not require regulatory approval.