Breeding for clubroot resistant spring canola (Brassica napusL.) for the Canadian prairies: Can the European winter canola cv. Mendel be used as a source of resistance?

Abstract

2011. Breeding for clubroot resistant spring canola (Brassica napus L.) for the Canadian prairies: Can the European winter canola cv. Mendel be used as a source of resistance? Can. J. Plant Sci. 91: 447Á458. Canola (Brassica napus L.) cultivars resistant to clubroot disease, caused by Plasmodiophora brassicae, are desired by the Canadian canola growers. Different genotypes of its two parental species B. rapa and B. olaeacea carry resistance to this disease. Furthermore, the European winter canola cultivar Mendel, which was bred through introgression of resistance from its parental species, also carries resistance to P. brassicae pathotypes prevelent in Europe. The objective of this study was to investigate the usefulness of resistance of Mendel for the development of clubroot-resistant canola cultivars for the Canadian prairies. For this, crosses between Mendel and two Canadian spring canola lines were made and pedigree breeding was followed. Plants with spring growth habit and resistant to P. brassicae pathotype 3 were recovered in the F 2 generation, apparently due to the involvement of major genes in the control of clubroot resistance and vernalization requirement. However, repeated selection over several generations was needed for the improvement of earliness. Most of these resistant lines also showed resistance to P. brassicae pathotypes 5 and 6, and had oil, protein, glucosinolate and saturated fatty acids acceptable to meet the Canadian canola standard. The test hybrids produced using the resistant F 6 lines and a male sterile line of the Male Sterility Lembke (MSL) system showed resistance to all three pathotypes in most cases. Furthermore, conversion of these clubroot resistant lines into cytoplasmic male sterile (CMS) line of the INRA-Ogura system and evaluation of the BC 2 CMS families for resistance revealed the possibilities of using clubroot resistant CMS lines for the development of clubroot resistant F 1 hybrid cultivars. However, despite rigorous selection for resistance performed in different generations, a small number of plants with visible disease symptoms appeared in some of the advanced generation pedigree lines and test hybrids, which is possibly due to the involvement of additional gene(s) in the control of clubroot resistance in these lines. Thus, data presented in this paper demonstrate the possibility of using the clubroot resistance of Mendel for the development of open-pollinated as well as hybrid canola cultivars for the Canadian prairies.

Mapping of the clubroot disease resistance in spring Brassica napus canola introgressed from European winter canola cv. ‘Mendel’

“…'Mendel' cross (Rahman et al 2011), were crossed to a clubroot susceptible spring canola line A07-26NR. The microspore culture technique, as described by Kebede et al (2010), was applied on a single plant basis to the F 1 's of A07-26NR 9 1CA0591.323 and A07-26NR 9 1CA0591.263 crosses for the development of 200 DH lines.…”

“…Hi-Q were included in the experiments as controls. The inoculated seedlings were kept in a greenhouse at 20-22/15°C day/ night and 16-h photoperiod as described by Rahman et al (2011). The plants, at the age of 6 weeks after inoculation, were scored for the disease symptom using the scale of 0-3 devised by Kuginuki et al (1999), where 0 = no galls, 1 = a few small galls, 2 = moderate galling, and 3 = severe galling.…”

“…To date five major loci, viz., CRk , Crr3 (Hirai et al 2004;Saito et al 2006), CRb (Piao et al 2004;Zhang et al 2014), CRa (Matsumoto et al 1998Hayashida et al 2008;Ueno et al 2012) and CRb Kato (Kato et al 2012(Kato et al , 2013 conferring resistance to clubroot disease have been mapped onto the A3 chromosome of B. rapa. Additional four clubroot resistance loci were mapped to four other chromosomes, such as, CRc to the chromosome A2 Matsumoto et al 2012), Crr1 to A8, Crr2 to A1, and Crr4 to A6 (Suwabe et al 2003 (Rahman et al 2011). However, use of this resistance in a commercial breeding program would require the knowledge of the genetic basis of the resistance as well as identification of molecular markers linked to the CR gene for use in markerassisted selection (MAS).…”

Potential loss of clubroot resistance genes from donor parent Brassica rapa subsp. rapifera (ECD 04) during doubled haploid production

“…Previous work by Rahman et al . () reported statistically significant distorted segregation ratios for resistance to susceptiblility in F 2 and F 3 families. This suggested that clubroot resistance derived from Mendel followed a complex mode of inheritance.…”

Identification of Plasmodiophora brassicae effectors — A challenging goal

“…Although there are some commercial clubroot-resistant (CR) canola and cabbage cultivars available, this resistance is associated with single dominant CR genes [11], as reported in Chinese cabbage [12] and oilseed rape [13], and leads to rapid breakdown. Two resistance genes have been isolated from Chinese cabbage ( Brassica rapa), CRa and Crr1 [14,15], while genetic mapping and identification of clubroot resistance has been also achieved in Brassica oleracea [16–19].…”