Breeding oilseed rape (Brassica napus L.) for durable disease resistance and improved seed cake nutritional quality

Oilseed rape (OSR) is the most important oilseed crop in Sweden.

Glucosinolates (GSLs) play important roles in defense against the most devastating soil-borne fungal pathogens like Verticillium longisporum and Sclerotinia sclerotiorum, causing Verticillium stem stripe (VSS) and Sclerotinia stem rot (SSR), respectively.

The earlier extensive breeding efforts to develop low seed GSL cultivars created intense selection pressure on the GSL biosynthesis, resulting in reduced GSL levels in leaves/roots, causing OSR to be susceptible to biotic stresses. Currently, no resistance genetic sources and effective fungicides are available.

Breeding OSR varieties with high GSLs in leaves/roots would thus be a desirable way to control VSS and SSR.

Moreover, some GSLs in seeds are anti-nutritional, making the protein-rich seed cake low-value feed and unsuitable for food use. GSLs are mainly synthesized in leaves and roots and relocated to seeds by GSLs transporter (GTR) genes.

This project aims to develop OSR mutants with high GSL levels in leaves/roots and low/no GSL in seeds by knocking out GTR genes using DNA-free CRISPR editing to achieve durable disease resistance and enhanced nutritional quality of seed cake.

We will also evaluate the functions of individual GTR genes in regulating tissue-specific GSL accumulation, which would form a molecular base for future breeding of OSR or related species by effectively regulating GTR gene expression to improve disease resistance.