Resistance mechanisms against thrips in Chrysanthemum and its relatives
Chrysanthemums are among the most important ornamental plants and are produced as cut flowers and as potted or garden plant. It is a high value crop, with a low tolerance for damage affecting the visual appearance. Especially for export there is a zero tolerance with respect to insects being present. Unfortunately, chrysanthemum cultivation suffers from insect pests, of which thrips are causing the biggest problem.
Thrips cause extensive damage, both directly by feeding, and indirectly by the viruses they transmit. Management of thrips is difficult due to their short life cycle, high reproduction rate, and cryptic behaviour. Although biological control is used, the main management tools are insecticides of various chemical classes due to zero tolerance. Environmental concerns have been raised with respect to insecticides as they not only increase mortality of the pest insect but also of its natural enemies. Furthermore, thrips develop resistance to these insecticides rapidly. Therefore, alternative strategies are urgently needed and host plant resistance is a very promising one. For implementation in chrysanthemum significant scientific breakthroughs in understanding the inheritance and mechanism of host plant resistance are extremely important.
The goals of this project are to characterize the thrips resistance present in cultivated and wild chrysanthemum materials, to identify novel sources of possibly different resistance mechanisms using a genetic approach with segregating populations, elucidating the resistance mechanism and providing the companies with easy to use breeding tools.
Breeding companies involved in the project are very much committed to increasing sustainability, including breeding, growing and wholesale, and will introduce/accumulate the resistance genes into cultivated materials, which will lead to new varieties that can be cultivated with significantly less or even without insecticides. Such varieties are expected to allow them to comply with the demands for export and result in a better income for the growers, and will lead when successful to a more sustainable production of Chrysanthemum.
The project will deliver knowledge on thrips resistance present in Chrysanthemum and related germplasm, as well as knowledge on the genetics and mechanism of the strongest thrips resistance identified in the project. It will also deliver the tools to introduce (or stack) the identified resistance components into novel varieties. When elucidated, the resistance mechanism may provide leads for obtaining insect resistance in other crops as well.
The intended results are:
1. An optimized evaluation method for determining thrips resistance in Chrysanthemum
2. Knowledge on thrips resistance levels in materials made available by the companies involved, identification of highly resistant and susceptible materials
3. Knowledge on the genetics of resistance, segregating population, segregation and QTL data
4. Knowledge on the resistance mechanism and possibly compounds involved
5. Knowledge on the effect of resistance on biological control agents
6. Plant material with improved resistance characteristics
7. A PhD thesis and papers in scientific journals