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Genome Wide Selection - a new technology to accelerate genetic improvement in Radiata pine tree breeding

Traditional tree breeding relies on scoring trees based on their observed physical characteristics, or phenotypes, along with their pedigree information to determine the breeding values for these trees. This process is often time-consuming. Many traits, such as wood quality traits, are best assessed at age 10, or even older, for Radiata pine.

Genome wide selection is a new technology that uses genetic markers on a genome (the whole genetic composition of an organism) to improve traits of economic importance. A genetic marker is a piece of DNA (a gene fragment) that is located on the chromosome close to genes with known biological functions, such as growth or disease resistance. Genome wide selection uses a specific type of genetic marker called single nucleotide polymorphism (SNP) that can be easily detected in large numbers in a genome. It is used as a molecular tool to quickly analyse multiple traits of a large number of individuals and generate genomic breeding values in one go. Genome wide selection of multiple traits can be performed on trees as young as seedlings in the nursery. The technology is also superior to traditional tree breeding on traits with: low heritability (e.g. tree growth); that are expensive to measure (e.g. disease resistance); or that are expressed late in life (e.g. wood quality of mature wood). Genomic selection is especially effective for species such as forest trees that take a long time to grow.

The Radiata Pine Breeding Company and Scion are starting a genomic selection programme with the aim of accelerating genetic improvement in Radiata pine. The importance of genomic selection to Radiata pine breeding is in eliminating the need for progeny testing, together with related improvements in bulking up technologies, in shortening the breeding and deployment cycle, and in increasing genetic gain per unit time. A scenario analysis of genomic selection in a Radiata pine breeding programme was conducted recently. The generation interval of a Radiata pine breeding population can be reduced from 17 years (forward selection) to about 7-9 years.

Deployment of genetic improvement to forest owners per unit time may be double or more. This will not only greatly hasten the deployment of genetic improvements to forest growers but also significantly lower the cost of the improvement programmes.

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