General introduction 1. Oilseed rape (Brassica napus)Oilseed rape (B. napus) is an economically important crop worldwide (Friedt et al. 2018).The origin of this species goes back to 7,500 years ago. B. napus allotetraploid genome (2n= 38= AACC) derives from a natural hybridization between B. rapa (2n= AA) and B. oleracea (2n= CC), followed by a chromosome doubling (Figure 1) . B. napus comes originally from the Mediterranean area and is the youngest species of the family Brassicaceae which includes 338 genera and 3,709 species. As a crop, B. napus was cultivated first in India as early as 4,000 BC (Bailey et al. 2006;Snowdon et al. 2007; Frieß et al. 2020). In Europe, domestication of B. napus occurred in the early middle ages (OECD, 1997).The importance of B. napus is attributed to its wide range of uses (Friedt et al. 2018). It is used as cooking oil, protein source, animal feed, biofuel and has various industrial uses such as producing inks, plastic cosmetics and bio-lubricants (Canola council of Canada, 2022). In Germany, oilseed rape is mainly used for biodiesel production (rapeseed oil methyl ester). In 2019, the production of 520,000 out of 900,000 ha of German oilseed rape growing areas was used for biodiesel (FNR, 2022). Moreover, oilseed rape is an important plant for honey bees, which can produce 60-90 kg of honey from each hectare cultivated with oilseed rape (Raboanatahiry et al. 2021).B. napus has many common names, such as rapeseed, colza, swede rape and canola (Orlovius, 2003). Canola is the name used to describe the double-low oil produced from cultivars developed in Canada. The oil of the double-low cultivars are healthier for human consumption due to the low erucic acid content (less than 2%), and their meal is suitable for feeding animals with low glucosinolate (< 30 mol/g) (Raboanatahiry et al. 2021). There are winter and spring types of oilseed rape and they differ mainly in their growing conditions and vernalisation requirements, where winter oilseed rape needs a prolonged cold period to be able to flower (Edwards et al. 2012;Raboanatahiry et al. 2021).Canada was the top producer of oilseed rape in 2020/2021 making more than a quarter of the global production (27%) alone, followed by the EU (22%), China (19%) and India (12%).Total worldwide production reached 29.2 million metric tons in 2020/2021 (Figure 2) (Statista, 2022). Oilseed rape cultivation was significantly intensified throughout the last decades.Jørgensen and Heick (2021) stated that the global cultivation area of oilseed rape increased by about 48% between 1995 and 2019. The productivity per hectare improved by 21% and
B. nigra BB
B. oleracea CC
B. rapa AA
B. carinata BBCC
B. juncea AABB
B. napus AACC
Phoma stem canker (blackleg disease)Phoma stem canker, also known as blackleg disease, is a cruciferous disease caused by two hemibiotrophic species: L. maculans and L. biglobosa (Mendes-Pereira et al. 2003). Both fungi belong to the phylum Ascomycota, the class Dothideomycetes, the order Pleosporales, the family Leptosphaeri...