Lehrstuhl für Pflanzenzüchtung

New genetic variation for silique shatter resistance in rapeseed

Schotenmessung

 

Background

A major issue in rapeseed cultivation is the pre-harvest seed loss. The fruits, so called siliques, dry out at maturity and become very fragile. Bad weather conditions as strong winds or hail can cause the siliques to break and shed the seeds. This does not only result in yield loss but the shattered seeds can also survive in the soil and germinate during the next growing seasons. During crop-rotation those volunteer plants are regarded as weeds. If the farmer decides to grow another rapeseed variety in the same field, volunteer plants of an inferior variety can reduce the quality of the harvest.

A network of transcription factors is involved in the development of the predetermined breaking point of the silique, the dehiscence zone. Knock-out mutations of INDEHISCENT (IND) and ALCATRAZ (ALC) produced shatter resistant fruits in Arabidopsis (Rajani and Sundaresan 2001; Liljegren et al. 2004).

Objectives

We are aiming at the production of shatter resistant rapeseed by the use of mutations in paralogs of IND and ALC. The objectives of this work are to obtain mutants both from an EMS (ethylmethanesulfonate) mutant population by conventional TILLING and from a targeted mutagenesis approach with a CRISPR/Cas9 system. Selected mutations will be combined by crossing and the resulting double mutant lines will be analyzed for shatter resistance. Three bench top phenotyping methods will be compared

Results

Prior to this work, a winter rapeseed TILLING resource was established by chemical mutagenesis with EMS (Harloff et al. 2012). TILLING fragments were designed to cover BnaA.IND.a, BnaC.IND.a, BnaA.ALC.a and BnaC.ALC.a. Among 3488 M2 plants we identified mutations of various kinds.

Shatter resistance measurements of M4-5 BnIND single mutants did not show an improvement of silique robustness. This was expected as B. napus houses two IND paralogs with supposedly redundant functions. However, combining different mutations by crossing to create double mutants resulted in significantly increased shatter resistance. For siliques obtained from the greenhouse, this tendency was consistent for three different phenotyping methods. Production of BnALC double mutants from the EMS material is currently in progress.

In parallel, we are working on targeted mutagenesis of shatter resistance genes. CRISPR/Cas9-induced mutations of two BnALC homoeologs were simultaneously produced by the use of a single target sequence. Thereby, this highly efficient way of genome editing directly yielded double mutants without any need for laborious crossings. Silique measurements of the T2 generation suggest an improved shatter resistance.

Project team

M.Sc. Janina Braatz
Dr. Hans-Joachim Harloff
Prof. Dr. Christian Jung

Scientific Partners

Prof. Dr. Stanislav Gorb, Dr. Lars Heepe, Zoological Institute, Functional Morphology and Biomechanics, Kiel University

Dr. Nils Stein, Dr. Axel Himmelbach, Dr. Martin Mascher, Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Stadt Seeland, Gatersleben
Institute of Clinical Molecular Biology (IKMB), Kiel University

Commercial Partners

Norddeutsche Pflanzenzucht Hans-Georg Lembke KG
NPZ Innovation GmbH
SAATEN-UNION BIOTEC GmbH

Publications

Braatz, J., Harloff, H.-J., Mascher, M., Stein, N., Himmelbach, A., Jung, C. (April 18, 2017).  CRISPR-Cas9 targeted mutagenesis leads to simultaneous modification of different homoeologous gene copies in polyploid oilseed rape (Brassica napus). Plant Physiology Preview. http://dx.doi.org/10.1104/pp.17.00426

Posters and Oral Presentations

Braatz, J., Emrani, N., Harloff, H.-J., Jung, C. (2017) Towards the production of shatter resistant rapeseed by use of mutations in dehiscence zone identity genes, International Plant & Animal Genome XXV, San Diego, 14.-18.01.2017. Oral presentation + poster.

Braatz, J., Emrani, N., Harloff, H.-J., Jung, C. (2016) Increasing seed shatter resistance in oilseed rape (B. napus L.) by TILLING and CRISPR/Cas9 mutagenesis, 2nd Sino-German Rapeseed Symposium, Kiel, 23.-26.05.2016. Oral Presentation.

Braatz, J., Emrani, N., Harloff, H.-J., Jung, C. (2016) Comparing seed shatter resistance in mutants of oilseed rape (B. napus L.), German Plant Breeding Conference, Bonn, 08.-10.03.2016. Poster.

Braatz, J., Emrani, N., Harloff, H.-J., Jung, C. (2016) Erzeugung von Ölraps mit erhöhter Schotenplatzfestigkeit, 66. Öffentliche Hochschultagung der Agrar- und Ernährungswissenschaftlichen Fakultät, Kiel, 04.02.2016. Poster.

Harloff, H.-J. (2015) Verbesserung der Schotenplatzfestigkeit in Raps, GFP Jahrestagung Öl- und Eiweißpflanzen, Bonn, 04.11.2015. Oral Presentation.

Braatz, J., Emrani, N., Harloff, H.-J., Jung, C. (2015) Seed shattering resistance in mutants of oilseed rape (B. napus L.), 18th Genome Research GPZ-Conference, Düsseldorf, 22-24.09. 2015. Oral Presentation

Financial Support

Funding has been provided by the Stiftung Schleswig-Holsteinische Landschaft under grant No. 2013/69

 

Updated: 303.05.2017           Responsible for this webpage: J. Braatz