Varieties with closed flowers - a useful strategy for restricting pollen dispersal in oilseed rape?

(2008 - 2011) Julius-Kühn-Institut (JKI), Federal Research Centre for Cultivated Plants (JKI), Institute for Biosafety of Genetically Modified Plants, Quedlingburg

Topic

Plants that pollinate and fertilize themselves inside closed flowers are called cleistogamic. As part of a breeding programme French scientists have been able to produce cleistogamy in oilseed rape by means of mutations.

Recently, research has been carried out into cleistogamy to examine whether it could be used for biological confinement in transgenic oilseed rape. This could restrict pollen-mediated gene transfer to neighbouring plants.

However, the trait is also of interest for conventional varieties when it comes to traceability and separating production of crops of different origins and qualities (identity preservation).

This project will examine the following questions:

What outcrossing behaviour is demonstrated by cleistogamic oilseed rape lines in realistic growing conditions?
Do cleistogamic lines differ from conventional high-yield varieties in terms of persistence (secondary dormancy )?
To what extent is it possible for breeders to implement a combination of the two confinement approaches - cleistogamy and low secondary dormancy?

Experiment description

Conventional oilseed rape - open flowers

Cleistogamic oilseed rape

Plot trial with cleistogamic and conventional oilseed rape

Photos: Dr. Alexandra Hüsken, JKI

Developing a method for quantifying outcrossing in cleistogamic varieties

The project aims to develop a suitable PCR method for quantifying outcrossing from cleistogamic varieties to conventional non-cleistogamic varieties. Since only a few genetic details are available about the cleistogamy gene in the oilseed rape line under investigation, molecular markers will have to be identified that can be used to detect and quantify incrossing from a cleistogamic oilseed rape plot to a recipient plot.

Outcrossing of cleistogamic varieties in the field

Ring tests at several locations will be conducted to determine the extent of incrossing of cleistogamic varieties into recipient oilseed rape varieties. Research will focus on the separation distance that needs to be observed between a cleistogamic and a non-cleistogamic oilseed rape plot in order to avoid exceeding a particular outcrossing threshold. To this end, a 0.5 hectare field will be planted with cleistogamic oilseed rape as a pollen source (donor). A 0.5 hectare plot will be planted downwind with non-cleistogamic oilseed rape as a pollen recipient. Oilseed rape plants at varying distances from the donor plot will be scored during the flowering period and samples will be collected at harvest time.

Secondary dormancy in seeds of cleistogamic varieties

Laboratory and field experiments will investigate whether there are differences between the conventional high-yield varieties and the cleistogamic line with regards to the expression of the secondary dormancy trait. The research (laboratory and field experiments) will be conducted on freshly harvested rape seeds.

The project is part of the joint project on "Developing and testing confinement strategies for oilseed rape". The network partners - the University of Hohenheim, the University of Göttingen and the Julius-Kühn-Institut (JKI) - are collaborating on laboratory analyses, the use of trial fields and data exchange for modelling.