In the Brassica family, kale, cabbage, cauliflower and turnip are major vegetables, while oilseed rape (Brassica napus L.) is a major oil crop in the world. Brassica crops are often attacked by three major types of diseases, Sclerotinia stem rot, blackleg, and Clubroot. Sclerotinia stem rot, caused by fugal pathogen Sclerotinia sclerotiorum results in heavy yield losses, ranging from 10-30% and may be up to 80% in outbreak years for oilseed rape production in China alone. Blackleg, caused by Leptosphaeria maculans, is one of the most serious diseases affecting canola/oilseed rape production in Australia, Europe and North America, with estimated annual crop losses at >US$900 million in these regions alone. Clubroot is caused by the obligate protist pathogen Plasmodiophora brassicae, and is a serious soil-borne disease of Brassica crops mainly in China and Canada, with regular yield losses of 10-15% and sometimes over 40%, or even total crop failure in heavily infested fields. Currently, breeding and cultivation of resistant varieties is considered as the most economical and effective approach for Sclerotinia stem rot, blackleg and clubroot management.
Due to the lack of highly resistant resources and currently known resistance sources are typically quantitative traits, breeding of Sclerotinia-resistant oilseed rape has been becoming difficult. A total of 18 specific R genes have been identified for blackleg resistance so far, while the genetic background for quantitative resistance is less understood. So far, a total of 26 loci have been mapped or cloned from different resistant materials worldwide for clubroot, using different marker systems. However, these loci have not been critically compared, and except for Crr1a and CRs, the functions of most CR genes have not been characterized. Additionally, as a given R gene often has a specific resistance/responsive to certain pathotypes, an oilseed rape/canola variety containing a single R locus will likely lose its resistance quickly, when used continuously in a heavily infested field. Therefore, there is a need to discover new resistance genes, clarify the relationship among all resistance loci identified, and study the underlying mechanisms, which is critical for developing novel strategies in resistance breeding by using the newest genomics technologies.
This Research Topic welcomes submissions around the following aspects of these Brassica diseases:
• Reviews: recent progress and challenges on resistance genetics and breeding, and provide perspectives/strategies for developing durable/highly resistant oilseed rape/canola varieties.
• Resistance germplasm innovation: research describing screening of natural resources of Brassica species and their relatives, and mutants generated through novel approaches to create resistance elite germplasm that could be used efficiently in the breeding process.
• Resistance-gene mapping and candidate gene identification: studies on novel resistance gene mapping, and candidate gene identification based on comparative genomics and map-based cloning/ other cloning strategy in order to provide solid platforms for utilizing these diverse resistance resources successfully.
• Resistance-gene interactions and resistance mechanisms: Functional validation of candidate genes, revealing the gene interactions or resistance mechanism under the regulation of different resistance genes based on multiple omics or other molecular technologies.
• Molecular breeding: research shedding the light on developing durable/highly resistance varieties that can overcome the pathotype specificity associated with a single R gene or week resistance performance. For example, pyramiding typical R/quantitative resistance genes into a variety based on the knowledge of resistance mechanism of each kind of resistance gene, or even novel resistance modes of action from non-hosts.
In the Brassica family, kale, cabbage, cauliflower and turnip are major vegetables, while oilseed rape (Brassica napus L.) is a major oil crop in the world. Brassica crops are often attacked by three major types of diseases, Sclerotinia stem rot, blackleg, and Clubroot. Sclerotinia stem rot, caused by fugal pathogen Sclerotinia sclerotiorum results in heavy yield losses, ranging from 10-30% and may be up to 80% in outbreak years for oilseed rape production in China alone. Blackleg, caused by Leptosphaeria maculans, is one of the most serious diseases affecting canola/oilseed rape production in Australia, Europe and North America, with estimated annual crop losses at >US$900 million in these regions alone. Clubroot is caused by the obligate protist pathogen Plasmodiophora brassicae, and is a serious soil-borne disease of Brassica crops mainly in China and Canada, with regular yield losses of 10-15% and sometimes over 40%, or even total crop failure in heavily infested fields. Currently, breeding and cultivation of resistant varieties is considered as the most economical and effective approach for Sclerotinia stem rot, blackleg and clubroot management.
Due to the lack of highly resistant resources and currently known resistance sources are typically quantitative traits, breeding of Sclerotinia-resistant oilseed rape has been becoming difficult. A total of 18 specific R genes have been identified for blackleg resistance so far, while the genetic background for quantitative resistance is less understood. So far, a total of 26 loci have been mapped or cloned from different resistant materials worldwide for clubroot, using different marker systems. However, these loci have not been critically compared, and except for Crr1a and CRs, the functions of most CR genes have not been characterized. Additionally, as a given R gene often has a specific resistance/responsive to certain pathotypes, an oilseed rape/canola variety containing a single R locus will likely lose its resistance quickly, when used continuously in a heavily infested field. Therefore, there is a need to discover new resistance genes, clarify the relationship among all resistance loci identified, and study the underlying mechanisms, which is critical for developing novel strategies in resistance breeding by using the newest genomics technologies.
This Research Topic welcomes submissions around the following aspects of these Brassica diseases:
• Reviews: recent progress and challenges on resistance genetics and breeding, and provide perspectives/strategies for developing durable/highly resistant oilseed rape/canola varieties.
• Resistance germplasm innovation: research describing screening of natural resources of Brassica species and their relatives, and mutants generated through novel approaches to create resistance elite germplasm that could be used efficiently in the breeding process.
• Resistance-gene mapping and candidate gene identification: studies on novel resistance gene mapping, and candidate gene identification based on comparative genomics and map-based cloning/ other cloning strategy in order to provide solid platforms for utilizing these diverse resistance resources successfully.
• Resistance-gene interactions and resistance mechanisms: Functional validation of candidate genes, revealing the gene interactions or resistance mechanism under the regulation of different resistance genes based on multiple omics or other molecular technologies.
• Molecular breeding: research shedding the light on developing durable/highly resistance varieties that can overcome the pathotype specificity associated with a single R gene or week resistance performance. For example, pyramiding typical R/quantitative resistance genes into a variety based on the knowledge of resistance mechanism of each kind of resistance gene, or even novel resistance modes of action from non-hosts.
