Molecular markers educational event by Aike Post at Deliflor Americas Headquarters

The chrysanthemum cultivation and breeding is facing many challenges.

I am therefore very proud of what we have achieved already. I am also very proud of the big steps we make here in Colombia with the new facilities which enable us to further improve the development of new varieties.?

In Breeding we work on 3 main topics: Attractive, Transportable and Growable.

In which attractive at home is the most important and automatically leads to the other 2 topics. We need to surprise with new products and therefore we have a broad assortment of 600 different varieties is al kind colours and shapes suitable for different circumstances.

In Holland we are facing challenges because of new growing techniques in climate, LED lighting and resilient soils. We also have total new growing concepts like Deep Flow Technique. All developments focusing on lower impact on the environment.?

More sustainable cultivation is not only triggered by legislation but also by costumer demand. Therefore more and more quality labels are used. We see this as very important and therefore Deliflor Latin America was the first carbon neutral flower company.?

For sustainable cultivation, plant health is very important. In our breeding program we work on many different disease resistances.?

In resistances we distinguish 2 main groups, full resistance and partial resistance.

Full resistance is a gene to gene interaction with 1 or few genes specific for a variety and specific for the race of the pathogen. Examples are Chrysanthemum White rust (Puccinia horiana)) and Fusarium wilt (Fusarium oxisporum ssp Chrysanthemii). For both we are testing different races to ensure the best resistance. Full resistance has good opportunities to work with molecular markers.

Partial resistance is more complex and very dependent on environmental circumstances. Examples are thrips and leaf miner. As testing is more complicated and mostly many genes are involved it is also more challenging to develop molecular markers.

At this moment we have routine testing for Fusarium, Verticillium, Pythium, Thrips, White rust and Leaf miner, and many disease bio-assays are on our wish-list.

To develop molecular markers in chrysanthemum is complex. Chrysanthemum has a large genome and there is hexasomic inheritance. We have a specialized and dedicated team of bio-informaticians who closely cooperate with Wageningen UR to develop tools. To improve this even further we have published those developments.

https://bmcgenomics.biomedcentral.com/articles/10.1186/s12864-017-4003-0

Nowadays we use molecular markers on different levels.?

For seedling selection. After germination of the seeds we take samples to the laboratory. Here we test for the different makers. Based upon the marker results we split the population in groups and we can eliminated susceptible plants. In the flowering stage we are aware of the resistances based upon the markers and select for the other characteristics.

In later stages we use the markers for decision support in flower trials and information about parents to improve our breeding program.

For the future we expect to make steps in image analysis. We already implemented for some traits but latest developments can help use to make better decisions in the field.?

We also invest in CRISPR/cas research. With this technique it is possible to make specific cuts in the genome. The plant restore this cuts by itself but the gene of interest will change like a natural mutation. This can help for better understanding and validation of gene functions, which lead to better markers. For commercial use there are many obstacles to take such as European legislation.?