Genomic breeding for accelerated improvement of growth, wood properties and plant defence in Eucalyptus grandis

Abstract

A significant benefit of genomic selection (GS) in forest trees is to reduce breeding cycle times and increase gains per unit time. Flowering time (seed-to-seed) of many forest tree species is a crucial factor contributing to the length of breeding cycles. In this study, we investigated the benefits of combining GS with transgenic Flowering locus T (FT)-scion for early floral induction (GS-FT) transgrafting approach in the precocious Eucalyptus grandis and non-precocious E. dunnii, two economically important plantation species. We simulated traditional breeding (TB), GS and GS-FT in the species and compared their transitional cost ratio and their benefit-cost ratio in terms of genetic gain. Implementation of GS and GS-FT compared to TB strategy was 10 to 13.8 fold more expensive for both species. Whereas the transition from GS to GS-FT strategy in both species is 1.2 fold more expensive. This resulted in a punitive benefit-cost ratio implementing GS and GS-FT strategies compared to the TB strategies. The implementation of the GS-FT, compared to the GS strategy, had a profitable benefit-cost ratio. With the adoption of the GS-FT strategy, which effectively removes flowering time as a barrier, similar breeding cycle times are achieved in both species, but E. dunnii benefits more due to the significant reduction in breeding cycle time. Our simulation provides a first indication of the potential benefits of implementing FT floral induction in conjunction with GS breeding strategies in plantation forest species.