Breeding and production of conifers – Clonal archives

Definition and Purpose

A clonal archive (or clone bank) is a collection of genetic individuals which are retained for:

• The commercial production of propagules
• Implementing a breeding strategy
• Genetic conservation.

The individuals within the clone bank may be raised from seeds but more commonly are grafts whereby scions from the genotype selected in a genetic test have been grafted onto a juvenile rootstock in the nursery prior to planting out in the clone bank. It is common for there to be multiple copies (ramets) of each clone and these are usually planted adjacent to each other within the clone bank.

Clone banks are constantly evolving. New selections are always being made in progeny and clonal tests for further breeding work prior to their being preserved in clone banks. As new and superior selections are made and placed in clone banks, the decision may be made to remove related but genetically inferior clones.

Management

The proposed management of all clonal archives is outlined in an internal Forest Research document: ‘Guide to conifer clone bank management’. This guide gives details of number of trees to be retained in each clonal archive, by species. Within each species, a genotype may be retained because it is a member of the production population, the breeding population, or the conservation population:

• Each population is represented on two sites (as an insurance measure)
• All genotypes is represented by two ramets on each site.

In future it is envisaged that clonal archives will be seen more as sources of scion material and that all controlled pollination work to meet breeding and production commitments, will be completed within the indoors in high-intensity polyhouses.