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.

Project goals

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 novel and are also expected to allow them to maintain or even increase their market share.

Expected results

From a scientific point of view the project will result in knowledge on resistance mechanisms that evolved in Chrysanthemum affecting thrips and perhaps other insects. It will also elucidate the genetics of thrips resistance in Chrysanthemum. From a social point of view this project will lead to a more sustainable production of Chrysanthemum. When elucidated, the resistance mechanism may provide leads for obtaining insect resistance in other crops as well.