Selection and breeding for insect and disease resistance
Results and analysis
The files below summarize what has been gathered to date. The activities or programmes recorded were classified into four categories that capture the current status of the work:
- Breeding programmes with deployed resistant material;
- Programmes breeding for resistance, no deployed material;
- Resistance detected in genetic/provenance trials;
- Evidence in genetic variation in resistance in seedling or clonal screens.
The information is still categorized under three broad approaches:
- traditional plant breeding methods;
- molecular biology approaches;
- genetic engineering.
While some research initiatives are still likely not documented here (e.g., overlooked or misclassified in terms of the three approach categories), it is hoped and expected that this information will be continuously updated as more people become aware of the resource and can provide feedback, updates or new information.
A total of 274 activities are now documented on breeding for insect and disease resistance in forest trees, which was 14 more than the first survey a few years ago. Again, note that these summary records were not intended to capture all publications of resistance on a particular species (e.g. the P. taeda fusiform resistance programme has hundreds of scientific publications in the literature), but to simply reflect on the activities relative to others around the world.
By forest tree species
Forty-three genera are now represented as opposed to 36 previously. Pines (Pinus spp.) and poplars (Populus spp.) are still the two most commonly investigated genera representing 30% and 23% respectively of all activities recorded. Eucalypts were the focus of 6% of the activities, which was a 1% increase over a few years ago; spruce (Picea spp.), birch (Betula spp.), larch (Larix spp.) and Douglas fir (Pseudotsuga spp.) almost 3% each; and chestnut (Castanea spp.), willows (Salix spp.) and elms (Ulmus spp.) at almost 2% each of all activities. Some new research in Acacia, Arbutus, Dalbergia, Eucalyptus hybrids, Juglans, Pinus (massoniana) and Lithocarpus are now present and documented.
The most studied tree species include Pinus radiata (16 records), P. taeda (9), and P. monticola and P. ponderosa var ponderosa (six records each). Picea abies, Pinus contorta, Betula pendula, Cryptomeria japonica, Eucalyptus globulus, Hevea braesilensis, Pinus lambertiana and Populus deltoides all still were each the focus of four of the activities/programmes.
By pest type and species
As was reported in the 2005 survey, over 55% of all activities reported in this review investigated tree resistance to disease species, over 36% targeted forest insect pests and over 6% investigated both pest types. Resistance to mammals was the focus of six of the activities (over 2%) and still one activity dealt with nematodes. Not surprisingly, little has changed over the past few years in the relative efforts in genetic studies among pest types.
The majority of research activities are published in developed countries, such as the United States (over 38% of all activities), China now 9%, and Canada, Japan, New Zealand, France and Australia all between 4-6%. A dozen or so other countries each add between 1-2% of the activities/programmes.
The majority of activities (70% over 68% previously) focus on traditional plant breeding methods (Approach 1). Genetic engineering (Approach 3) was the focus of 37 (13%) of the activities while molecular biology approaches (Approach 2) were investigated in 32 of the activities (almost 12%). Thirteen of the activities used a combination of the three approaches.
The majority of research activities, 164 representing almost 60% of all activities, have provided evidence of genetic variation in resistance in seedling or clonal screens (Status 4). This is down by 3% which is probably due to some programmes moving ‘up in status’ to more operational deployment. In 67 of the activities, resistance has been detected in genetic/provenance trials (Status 3), which is up by 10 activities/programmes. Twenty-three updated activities (same as before) represent breeding programmes with deployed resistant material (Status 1) while 21 of the activities represent breeding for resistance programmes but with no deployed material (Status 2) (an increase of five).