Exploring natural resistance in vegetable crops never stops

The most sustainable way to prevent diseases and pests in vegetable cultivation is to develop varieties that are resistant. Developing a new variety used to take more than twenty years, but thanks to new technologies, such as tissue culture, marker technology and bioinformatics, we can reduce that period to just four to eight years.

All around the world, vegetable growers provide healthy and tasty products that meet the requirements of the consumer. These professionals are used to working with the possibilities and challenges that nature offers them.

An important part of their work is to prevent diseases and pests. Sometimes a pesticide is necessary to keep a crop healthy, but growers prefer to use chemicals as little as possible. Treatment often demands energy from the plant and involves costs. Moreover, there are diseases and pests for which no pesticides are available at all, like clubroot (Plasmodiophora brassicae), a soil-borne pathogen that can cause serious damage to brassicas, such as cabbage crops.

Natural resistance

Nature often provides the solution. Some plants have a natural resistance to fungal or bacterial infections and some can even defend themselves against pests. From these useful, inherited characteristics, breeders can make a selection and develop varieties that have acquired these resistance characteristics.

Bejo has already developed varieties using these techniques, such as red cabbage, pak choi, Chinese cabbage, white cabbage and cauliflower, that are resistant to certain strains (physios) of clubroot.

Traditional breeding is a process of selecting plants with the desired characteristics and cross-breeding them over many generations. It generally takes approximately twenty years before a new variety is ready to be introduced to the market using this classic method. Modern breeding companies can do this much faster thanks to 'life sciences', such as tissue culture, the use of DNA markers and bioinformatics, resulting in a reduced time frame of just four to eight years – depending on the variety.

Start in the field

How does this work in practice? Bejo begins in the field where our representatives visit vegetable growers on a daily basis. They are the first to notice an outbreak of a specific plant disease, e.g. a fungus, in a region. If a structural cultivation problem arises, this could be an opportunity for Bejo to start a disease resistance breeding programme.

Isolating pathogens

It is important when breeding for resistance to know the pathogen and the variant (physio) concerned. For example, of the previously mentioned clubroot there are at least nine known physios. These variants are often specific to certain regions or climates.

Breeding for resistance starts by identifying the cause, and our researchers do that in the Phytopathology & Content Analysis department. They isolate the pathogen which is then cultured to reproduce it. This results in a so-called isolate which is then used to carry out a ‘disease test’. In other words: they infect a population of plants. Any plants that remain healthy are selected by our breeders as the basis for a resistant variety.