Yongju Huang - Academia.edu (original) (raw)

Papers by Yongju Huang

Research paper thumbnail of アブラナ(Brassica napus)におけるLeptosphaeria maculansに対する耐性の環境で安定なQTLの同定

Theoretical and Applied Genetics, 2016

Research paper thumbnail of Maturation of Leptosphaeria maculans pseudothecia in relation to forecasting phoma leaf spots (stem canker) on oilseed rape

At Rothamsted in 2000/2001 and 2001/2002, pseudothecia on oilseed rape stem bases matured earlier... more At Rothamsted in 2000/2001 and 2001/2002, pseudothecia on oilseed rape stem bases matured earlier than those on upper stems. The first release of ascospores in 2001 was 6 days earlier than in 2000, but the majority of ascospores were released between October and late December in both seasons. Phoma leaf spotting appeared 8-15 days after first release of ascospores. Phoma leaf spotting and stem canker were 13 days earlier in 2001 than in 2000. Seasonal differences in maturation of pseudothecia were related to differences in summer rainfall; with more rainfall in summer maturation of pseudothecia, release of ascospores, and subsequently leaf infection and appearance of stem canker were earlier.

Research paper thumbnail of Correction to: Incorporating pleiotropic quantitative trait loci in dissection of complex traits: seed yield in rapeseed as an example

Theoretical and Applied Genetics, Nov 30, 2017

Research paper thumbnail of Leptosphaeria maculans isolates with variations in AvrLm1 and AvrLm4 effector genes induce differences in defence responses but not in resistance phenotypes in cultivars carrying the Rlm7 gene

Research paper thumbnail of Leptosphaeria biglobosa inhibits the production of sirodesmin PL by L. maculans

Pest Management Science

BACKGROUNDPhoma stem canker is caused by two coexisting pathogens, Leptosphaeria maculans and L. ... more BACKGROUNDPhoma stem canker is caused by two coexisting pathogens, Leptosphaeria maculans and L. biglobosa. They coexist because of their temporal and spatial separations, which are associated with the differences in timing of their ascospore release. L. maculans produces sirodesmin PL, while L. biglobosa does not. However, their interaction/coexistence in terms of secondary metabolite production is not understood.RESULTSSecondary metabolites were extracted from liquid cultures, L. maculans only (Lm only), L. biglobosa only (Lb only), L. maculans and L. biglobosa simultaneously (Lm&Lb) or sequentially 7 days later (Lm+Lb). Sirodesmin PL or its precursors were identified in extracts from ‘Lm only’ and ‘Lm+Lb’, but not from ‘Lm&Lb’. Metabolites from ‘Lb only’, ‘Lm&Lb’ or ‘Lm+Lb’ caused significant reductions in L. maculans colony area. However, only the metabolites containing sirodesmin PL caused a significant reduction to L. biglobosa colony area. When oilseed rape cotyledons were in...

Research paper thumbnail of Effective control of Leptosphaeria maculans increases importance of L. biglobosa as a cause of phoma stem canker epidemics on oilseed rape

Pest Management Science

BACKGROUNDPhoma stem canker is a damaging disease of oilseed rape caused by two related fungal sp... more BACKGROUNDPhoma stem canker is a damaging disease of oilseed rape caused by two related fungal species, Leptosphaeria maculans and L. biglobosa. However, previous work has mainly focused on L. maculans and there has been little work on L. biglobosa. This work provides evidence of the importance of L. biglobosa to stem canker epidemics in the UK.RESULTSQuantification of L. maculans and L. biglobosa DNA using species‐specific quantitative PCR showed that L. biglobosa caused both upper stem lesions and stem base cankers on nine oilseed rape cultivars in the UK. Upper stem lesions were mainly caused by L. biglobosa. For stem base cankers, there was more L. maculans DNA than L. biglobosa DNA in the susceptible cultivar Drakkar, while there was more L. biglobosa DNA than L. maculans DNA in cultivars with the resistance gene Rlm7 against L. maculans. The frequency of L. biglobosa detected in stem base cankers increased from 14% in 2000 to 95% in 2013. Ascospores of L. biglobosa and L. macu...

Research paper thumbnail of Azole fungicide sensitivity and molecular mechanisms of reduced sensitivity in Irish Pyrenopeziza brassicae populations

Pest Management Science

BACKGROUNDLight leaf spot, caused by Pyrenopeziza brassicae, is amongst the most damaging disease... more BACKGROUNDLight leaf spot, caused by Pyrenopeziza brassicae, is amongst the most damaging diseases of winter oilseed rape (Brassica napus), and currently the sterol 14α‐demethylase (CYP51) inhibitors (azoles) represent the main class of fungicides used to control light leaf spot development. However, a shift in sensitivity to azole fungicides in P. brassicae populations has been observed in different European countries, including Ireland.RESULTSTo assess the sensitivity status of Irish P. brassicae populations to azole fungicides, three collections of P. brassicae from 2018–2020 were tested in vitro against tebuconazole and prothioconazole‐desthio, and the PbCYP51 gene targeted by this class of fungicides was genotyped in different isolates. A change in sensitivity to azole fungicides was observed and differences in sensitivity to tebuconazole between Irish populations were present. There were two substitutions within PbCYP51 (G460S and S508T) and inserts of different sizes in its p...

Research paper thumbnail of Stem Canker of oilseed rape : Molecular methods and mathematical modelling to deploy durable resistance

Research paper thumbnail of Prediction of ascospore release of Leptosphaeria spp. to improve timing of fungicide applications

Research paper thumbnail of Research on ultra-dry storage of soybean seeds

Zhongguo you Liao zuo wu xue bao = Chinese Journal of oil Crop Sciences, 2000

In order to further explore the effects of ultra dry storage protein riched seeds, soybean seeds ... more In order to further explore the effects of ultra dry storage protein riched seeds, soybean seeds of Zhongdou No.24 and Taixing Heidou were dried to ten different moisture contents using CaCl 2, then sealed and stored at 25℃ and 5℃ for one year respectively. Changes of viability and vigour of the stored seeds had been monitored. The results showed that Zhongdou No.24 and Taixing Heidou were suitable for ultra dry storage and the optimum moisture contents obtained at 50℃, 25℃ and 5℃ were different. The optimum moisture content of seeds of Zhongdou No.24 at 25℃ and 5℃ was 6.0%. The optimum moisture content of seeds of Taixing Heidou at 25℃ was 5.4%; at 5℃ was 6.0%.

Research paper thumbnail of Pathogenicity of Leptosphaeria biglobosa to oilseed rape (Brassica napus) cultivars differing in resistance against Leptosphaeria maculans

Research paper thumbnail of Cloning of plant defensin and oxalic acid oxidase genes and expressions of these genes induced by pathogens and chemicals in Brassica napus

PDF1.2(plant defensin 1.2)and oxalic acid oxidase (OXO) genes were cloned using PCR-based methods... more PDF1.2(plant defensin 1.2)and oxalic acid oxidase (OXO) genes were cloned using PCR-based methods. Primers for PCR were designed based on sequences of PDF genes of Arabidopsis thaliana and Brassica oleracea, an antifungal protein of B. napus for PDF1.2 amplification, and OXO gene of B. napus for OXO amplification. Sequences of 470bp for PDF1.2 and 629bp for OXO were obtained by the amplification based on genomic DNA of B.napus cv. Maddrigal, and cloned separately into a vector. There were 42%～71% identity between the cloned PDF1.2 and any of relevant sequences in the GenBank and above 70% identity between the cloned OXO and any of relevant sequences in the GenBank. Expressions of the two genes were investigated in B.napus using real-time quantitative PCR. B. napus seedlings were induced by inoculation with Leptosphaeria biglobosa or spraying with acibenzolar-s-methyl (ASM) in the first true leaves, and 24h later were challenge inoculated with L. maculans in the first and second true...

Research paper thumbnail of Investigating the risk of severe phoma stem canker caused by Leptosphaeria biglobosa on winter oilseed rape in UK

Aspects of applied biology, 2017

Research paper thumbnail of Research on ultra-dry storage for soyabean seeds. I. Effects of simulated aging at 50°C on the viability and physiological characters of the seeds

Chinese journal of oil crop sciences, 2000

Research paper thumbnail of Combining R gene and quantitative resistance increases effectiveness of cultivar resistance against Leptosphaeria maculans in Brassica napus in different environments

PloS one, 2018

Using cultivar resistance against pathogens is one of the most economical and environmentally fri... more Using cultivar resistance against pathogens is one of the most economical and environmentally friendly methods for control of crop diseases. However, cultivar resistance can be easily rendered ineffective due to changes in pathogen populations or environments. To test the hypothesis that combining R gene-mediated resistance and quantitative resistance (QR) in one cultivar can provide more effective resistance than use of either type of resistance on its own, effectiveness of resistance in eight oilseed rape (Brassica napus) cultivars with different R genes and/or QR against Leptosphaeria maculans (phoma stem canker) was investigated in 13 different environments/sites over three growing seasons (2010/2011, 2011/2012 and 2012/2013). Cultivar Drakkar with no R genes and no QR was used as susceptible control and for sampling L. maculans populations. Isolates of L. maculans were obtained from the 13 sites in 2010/2011 to assess frequencies of avirulent alleles of different effector genes...

Research paper thumbnail of The SECURE project – Stem canker of oilseed rape: : molecular methods and mathematical modelling to deploy durable resistance

N Evans et al, "The SECURE Project - Stem Canker of oilseed rape: Molecular methods and math... more N Evans et al, "The SECURE Project - Stem Canker of oilseed rape: Molecular methods and mathematical modeling to deploy durable resistance", in Vol 4 of the Proceedings of the 12th International Rapeseed Congress : Sustainable Development in Cruciferous Oilseed Crops Production, Wuhan, China, March 26 - 30, 2007. The proceedings are available online at: http://gcirc.org/intranet/irc-proceedings/12th-irc-wuhan-china-2007-vol-4.html

Research paper thumbnail of Effects of different fungicides on the severity of phoma stem canker

Poster abstractPhoma stem canker, a disease of oilseed rape (Brassica napus) caused by sibling pa... more Poster abstractPhoma stem canker, a disease of oilseed rape (Brassica napus) caused by sibling pathogens Leptosphaeria maculans and L. biglobosa. Both pathogens follow a monocylic disease cycle that causes leaf spotting in autumn/winter and stem cankers in spring/summer. Most severe cankers decrease transportation of water and nutrients. Fungicides are important for phoma stem canker control. Triazole fungicides currently dominate the market, although reduced sensitivity in some plant pathogen species is a concern. Moreover, L. maculans and L. biglobosa have shown differing level of sensitivity to triazole fungicides. Therefore, increased knowledge on controlling phoma stem canker using non-triazole based fungicides is essential. Field trials were established for 2013/2014 cropping season. Four fungicides were applied: penthiopyrad, picoxystrobin, prothioconazole and a novel fungicide. Spray timings were divided into three sprays T1 (phoma leaf spotting incidence ≥10%), T2 (3/4 weeks post T1) and T3 (Sclerotinia). Phoma leaf spotting incidence and stem canker severity were recorded. In vitro sensitivity testing was done on one L. maculans (ME24) and one L. biglobosa (68) isolate. Prothioconazole showed no noteworthy advantage over the novel fungicide in canker severity scoring. No significant difference in growth inhibition was observed between L. biglobosa and L. maculans (P ≤ 0.05) when treated with novel fungicide. Canker severity indicates that the novel fungicide has a similar efficacy to triazole fungicides. Fungicide sensitivity testing shows that L. biglobosa does not have an increased sensitivity to non-triazole fungicides. This interaction suggests that the novel fungicide could be used to control both L. maculans and L. biglobosaNon peer reviewe

Research paper thumbnail of Oilseed rape (Brassica napus) resistance to growth of Leptosphaeria maculans in leaves of young plants contributes to quantitative resistance in stems of adult plants

PLOS ONE, 2019

Key message: One QTL for resistance against Leptosphaeria maculans growth in leaves of young plan... more Key message: One QTL for resistance against Leptosphaeria maculans growth in leaves of young plants in controlled environments overlapped with one QTL detected in adult plants in field experiments. The fungal pathogen Leptosphaeria maculans initially infects leaves of oilseed rape (Brassica napus) in autumn in Europe and then grows systemically from leaf lesions along the leaf petiole to the stem, where it causes damaging phoma stem canker (blackleg) in summer before harvest. Due to the difficulties of investigating resistance to L. maculans growth in leaves and petioles under field conditions, identification of quantitative resistance typically relies on end of season stem canker assessment on adult plants. To investigate whether quantitative resistance can be detected in young plants, we first selected nine representative DH (doubled haploid) lines from an oilseed rape DY ('Darmor-bzh' × 'Yudal') mapping population segregating for quantitative resistance against L. maculans for controlled environment experiment (CE). We observed a significant correlation between distance grown by L. maculans along the leaf petiole towards the stem (r = 0.91) in CE experiments and the severity of phoma stem canker in field experiments. To further investigate quantitative trait loci (QTL) related to resistance against growth of L. maculans in leaves of young plants in CE experiments, we selected 190 DH lines and compared the QTL detected in CE experiments with QTL related to stem canker severity in stems of adult plants in field experiments. Five QTL for resistance to L. maculans growth along the leaf petiole were detected; collectively they explained 35% of the variance. Two of these were also detected in leaf lesion area assessments and each explained 10-12% of the variance. One QTL on A02 co-localized with a QTL detected in stems of adult plants in field experiments. This suggests that resistance to the growth of L. maculans from leaves along the petioles towards the stems contributes to the quantitative resistance assessed in stems of adult plants in field experiments at the end of the growing season.

Research paper thumbnail of Effects of cultivar resistance and fungicide application on stem canker of oilseed rape ( Brassica napus ) and potential interseasonal transmission of Leptosphaeria spp. inoculum

Plant Pathology, 2021

Phoma stem canker (also known as blackleg) is caused by two closely related coexisting ascomycete... more Phoma stem canker (also known as blackleg) is caused by two closely related coexisting ascomycete fungal pathogens, Leptosphaeria maculans and L. biglobosa (Fitt et al., 2006a; Shoemaker & Brun, 2001). This disease causes damage to oilseed rape worldwide (Fitt et al., 2006b) and accounts for annual yield losses to UK oilseed rape growers worth approximately £100 million, despite the use of fungicides and resistant cultivars (www.cropm onitor.co.uk) (Zhang et al., 2014). In the UK, phoma stem canker is a monocyclic disease that is initiated by ascospores as primary inoculum in autumn or winter. These ascospores are released from pseudothecia (sexual fruiting bodies) that mature after harvest on infected stem debris, such as stubble left in fields from the previous cropping season. Once mature, ascospores

Research paper thumbnail of Quantitative Trait Locus Mapping for Resistance Against Pyrenopeziza brassicae Derived From a Brassica napus Secondary Gene Pool

Frontiers in Plant Science, 2022

Use of host resistance is the most economical and environmentally safe way to control light leaf ... more Use of host resistance is the most economical and environmentally safe way to control light leaf spot disease of oilseed rape (Brassica napus). The causal organism of light leaf spot, Pyrenopeziza brassicae, is one of the most economically damaging pathogens of oilseed rape in the United Kingdom and it is considered to have a high potential to evolve due to its mixed reproduction system and airborne ascospores. This necessitates diverse sources of host resistance, which are inadequate at present to minimize yield losses caused by this disease. To address this, we screened a doubled haploid (DH) population of oilseed rape, derived from a secondary gene pool (ancestral genomes) of B. napus for the introgression of resistance against P. brassicae. DH lines were phenotyped using controlled-environment and glasshouse experiments with P. brassicae populations obtained from three different geographic locations in the United Kingdom. Selected DH lines with different levels of resistance wer...

Research paper thumbnail of アブラナ(Brassica napus)におけるLeptosphaeria maculansに対する耐性の環境で安定なQTLの同定

Theoretical and Applied Genetics, 2016

Research paper thumbnail of Maturation of Leptosphaeria maculans pseudothecia in relation to forecasting phoma leaf spots (stem canker) on oilseed rape

At Rothamsted in 2000/2001 and 2001/2002, pseudothecia on oilseed rape stem bases matured earlier... more At Rothamsted in 2000/2001 and 2001/2002, pseudothecia on oilseed rape stem bases matured earlier than those on upper stems. The first release of ascospores in 2001 was 6 days earlier than in 2000, but the majority of ascospores were released between October and late December in both seasons. Phoma leaf spotting appeared 8-15 days after first release of ascospores. Phoma leaf spotting and stem canker were 13 days earlier in 2001 than in 2000. Seasonal differences in maturation of pseudothecia were related to differences in summer rainfall; with more rainfall in summer maturation of pseudothecia, release of ascospores, and subsequently leaf infection and appearance of stem canker were earlier.

Research paper thumbnail of Correction to: Incorporating pleiotropic quantitative trait loci in dissection of complex traits: seed yield in rapeseed as an example

Theoretical and Applied Genetics, Nov 30, 2017

Research paper thumbnail of Leptosphaeria maculans isolates with variations in AvrLm1 and AvrLm4 effector genes induce differences in defence responses but not in resistance phenotypes in cultivars carrying the Rlm7 gene

Research paper thumbnail of Leptosphaeria biglobosa inhibits the production of sirodesmin PL by L. maculans

Pest Management Science

BACKGROUNDPhoma stem canker is caused by two coexisting pathogens, Leptosphaeria maculans and L. ... more BACKGROUNDPhoma stem canker is caused by two coexisting pathogens, Leptosphaeria maculans and L. biglobosa. They coexist because of their temporal and spatial separations, which are associated with the differences in timing of their ascospore release. L. maculans produces sirodesmin PL, while L. biglobosa does not. However, their interaction/coexistence in terms of secondary metabolite production is not understood.RESULTSSecondary metabolites were extracted from liquid cultures, L. maculans only (Lm only), L. biglobosa only (Lb only), L. maculans and L. biglobosa simultaneously (Lm&Lb) or sequentially 7 days later (Lm+Lb). Sirodesmin PL or its precursors were identified in extracts from ‘Lm only’ and ‘Lm+Lb’, but not from ‘Lm&Lb’. Metabolites from ‘Lb only’, ‘Lm&Lb’ or ‘Lm+Lb’ caused significant reductions in L. maculans colony area. However, only the metabolites containing sirodesmin PL caused a significant reduction to L. biglobosa colony area. When oilseed rape cotyledons were in...

Research paper thumbnail of Effective control of Leptosphaeria maculans increases importance of L. biglobosa as a cause of phoma stem canker epidemics on oilseed rape

Pest Management Science

BACKGROUNDPhoma stem canker is a damaging disease of oilseed rape caused by two related fungal sp... more BACKGROUNDPhoma stem canker is a damaging disease of oilseed rape caused by two related fungal species, Leptosphaeria maculans and L. biglobosa. However, previous work has mainly focused on L. maculans and there has been little work on L. biglobosa. This work provides evidence of the importance of L. biglobosa to stem canker epidemics in the UK.RESULTSQuantification of L. maculans and L. biglobosa DNA using species‐specific quantitative PCR showed that L. biglobosa caused both upper stem lesions and stem base cankers on nine oilseed rape cultivars in the UK. Upper stem lesions were mainly caused by L. biglobosa. For stem base cankers, there was more L. maculans DNA than L. biglobosa DNA in the susceptible cultivar Drakkar, while there was more L. biglobosa DNA than L. maculans DNA in cultivars with the resistance gene Rlm7 against L. maculans. The frequency of L. biglobosa detected in stem base cankers increased from 14% in 2000 to 95% in 2013. Ascospores of L. biglobosa and L. macu...

Research paper thumbnail of Azole fungicide sensitivity and molecular mechanisms of reduced sensitivity in Irish Pyrenopeziza brassicae populations

Pest Management Science

BACKGROUNDLight leaf spot, caused by Pyrenopeziza brassicae, is amongst the most damaging disease... more BACKGROUNDLight leaf spot, caused by Pyrenopeziza brassicae, is amongst the most damaging diseases of winter oilseed rape (Brassica napus), and currently the sterol 14α‐demethylase (CYP51) inhibitors (azoles) represent the main class of fungicides used to control light leaf spot development. However, a shift in sensitivity to azole fungicides in P. brassicae populations has been observed in different European countries, including Ireland.RESULTSTo assess the sensitivity status of Irish P. brassicae populations to azole fungicides, three collections of P. brassicae from 2018–2020 were tested in vitro against tebuconazole and prothioconazole‐desthio, and the PbCYP51 gene targeted by this class of fungicides was genotyped in different isolates. A change in sensitivity to azole fungicides was observed and differences in sensitivity to tebuconazole between Irish populations were present. There were two substitutions within PbCYP51 (G460S and S508T) and inserts of different sizes in its p...

Research paper thumbnail of Stem Canker of oilseed rape : Molecular methods and mathematical modelling to deploy durable resistance

Research paper thumbnail of Prediction of ascospore release of Leptosphaeria spp. to improve timing of fungicide applications

Research paper thumbnail of Research on ultra-dry storage of soybean seeds

Zhongguo you Liao zuo wu xue bao = Chinese Journal of oil Crop Sciences, 2000

In order to further explore the effects of ultra dry storage protein riched seeds, soybean seeds ... more In order to further explore the effects of ultra dry storage protein riched seeds, soybean seeds of Zhongdou No.24 and Taixing Heidou were dried to ten different moisture contents using CaCl 2, then sealed and stored at 25℃ and 5℃ for one year respectively. Changes of viability and vigour of the stored seeds had been monitored. The results showed that Zhongdou No.24 and Taixing Heidou were suitable for ultra dry storage and the optimum moisture contents obtained at 50℃, 25℃ and 5℃ were different. The optimum moisture content of seeds of Zhongdou No.24 at 25℃ and 5℃ was 6.0%. The optimum moisture content of seeds of Taixing Heidou at 25℃ was 5.4%; at 5℃ was 6.0%.

Research paper thumbnail of Pathogenicity of Leptosphaeria biglobosa to oilseed rape (Brassica napus) cultivars differing in resistance against Leptosphaeria maculans

Research paper thumbnail of Cloning of plant defensin and oxalic acid oxidase genes and expressions of these genes induced by pathogens and chemicals in Brassica napus

PDF1.2(plant defensin 1.2)and oxalic acid oxidase (OXO) genes were cloned using PCR-based methods... more PDF1.2(plant defensin 1.2)and oxalic acid oxidase (OXO) genes were cloned using PCR-based methods. Primers for PCR were designed based on sequences of PDF genes of Arabidopsis thaliana and Brassica oleracea, an antifungal protein of B. napus for PDF1.2 amplification, and OXO gene of B. napus for OXO amplification. Sequences of 470bp for PDF1.2 and 629bp for OXO were obtained by the amplification based on genomic DNA of B.napus cv. Maddrigal, and cloned separately into a vector. There were 42%～71% identity between the cloned PDF1.2 and any of relevant sequences in the GenBank and above 70% identity between the cloned OXO and any of relevant sequences in the GenBank. Expressions of the two genes were investigated in B.napus using real-time quantitative PCR. B. napus seedlings were induced by inoculation with Leptosphaeria biglobosa or spraying with acibenzolar-s-methyl (ASM) in the first true leaves, and 24h later were challenge inoculated with L. maculans in the first and second true...

Research paper thumbnail of Investigating the risk of severe phoma stem canker caused by Leptosphaeria biglobosa on winter oilseed rape in UK

Aspects of applied biology, 2017

Research paper thumbnail of Research on ultra-dry storage for soyabean seeds. I. Effects of simulated aging at 50°C on the viability and physiological characters of the seeds

Chinese journal of oil crop sciences, 2000

Research paper thumbnail of Combining R gene and quantitative resistance increases effectiveness of cultivar resistance against Leptosphaeria maculans in Brassica napus in different environments

PloS one, 2018

Using cultivar resistance against pathogens is one of the most economical and environmentally fri... more Using cultivar resistance against pathogens is one of the most economical and environmentally friendly methods for control of crop diseases. However, cultivar resistance can be easily rendered ineffective due to changes in pathogen populations or environments. To test the hypothesis that combining R gene-mediated resistance and quantitative resistance (QR) in one cultivar can provide more effective resistance than use of either type of resistance on its own, effectiveness of resistance in eight oilseed rape (Brassica napus) cultivars with different R genes and/or QR against Leptosphaeria maculans (phoma stem canker) was investigated in 13 different environments/sites over three growing seasons (2010/2011, 2011/2012 and 2012/2013). Cultivar Drakkar with no R genes and no QR was used as susceptible control and for sampling L. maculans populations. Isolates of L. maculans were obtained from the 13 sites in 2010/2011 to assess frequencies of avirulent alleles of different effector genes...

Research paper thumbnail of The SECURE project – Stem canker of oilseed rape: : molecular methods and mathematical modelling to deploy durable resistance

N Evans et al, "The SECURE Project - Stem Canker of oilseed rape: Molecular methods and math... more N Evans et al, "The SECURE Project - Stem Canker of oilseed rape: Molecular methods and mathematical modeling to deploy durable resistance", in Vol 4 of the Proceedings of the 12th International Rapeseed Congress : Sustainable Development in Cruciferous Oilseed Crops Production, Wuhan, China, March 26 - 30, 2007. The proceedings are available online at: http://gcirc.org/intranet/irc-proceedings/12th-irc-wuhan-china-2007-vol-4.html

Research paper thumbnail of Effects of different fungicides on the severity of phoma stem canker

Poster abstractPhoma stem canker, a disease of oilseed rape (Brassica napus) caused by sibling pa... more Poster abstractPhoma stem canker, a disease of oilseed rape (Brassica napus) caused by sibling pathogens Leptosphaeria maculans and L. biglobosa. Both pathogens follow a monocylic disease cycle that causes leaf spotting in autumn/winter and stem cankers in spring/summer. Most severe cankers decrease transportation of water and nutrients. Fungicides are important for phoma stem canker control. Triazole fungicides currently dominate the market, although reduced sensitivity in some plant pathogen species is a concern. Moreover, L. maculans and L. biglobosa have shown differing level of sensitivity to triazole fungicides. Therefore, increased knowledge on controlling phoma stem canker using non-triazole based fungicides is essential. Field trials were established for 2013/2014 cropping season. Four fungicides were applied: penthiopyrad, picoxystrobin, prothioconazole and a novel fungicide. Spray timings were divided into three sprays T1 (phoma leaf spotting incidence ≥10%), T2 (3/4 weeks post T1) and T3 (Sclerotinia). Phoma leaf spotting incidence and stem canker severity were recorded. In vitro sensitivity testing was done on one L. maculans (ME24) and one L. biglobosa (68) isolate. Prothioconazole showed no noteworthy advantage over the novel fungicide in canker severity scoring. No significant difference in growth inhibition was observed between L. biglobosa and L. maculans (P ≤ 0.05) when treated with novel fungicide. Canker severity indicates that the novel fungicide has a similar efficacy to triazole fungicides. Fungicide sensitivity testing shows that L. biglobosa does not have an increased sensitivity to non-triazole fungicides. This interaction suggests that the novel fungicide could be used to control both L. maculans and L. biglobosaNon peer reviewe

Research paper thumbnail of Oilseed rape (Brassica napus) resistance to growth of Leptosphaeria maculans in leaves of young plants contributes to quantitative resistance in stems of adult plants

PLOS ONE, 2019

Key message: One QTL for resistance against Leptosphaeria maculans growth in leaves of young plan... more Key message: One QTL for resistance against Leptosphaeria maculans growth in leaves of young plants in controlled environments overlapped with one QTL detected in adult plants in field experiments. The fungal pathogen Leptosphaeria maculans initially infects leaves of oilseed rape (Brassica napus) in autumn in Europe and then grows systemically from leaf lesions along the leaf petiole to the stem, where it causes damaging phoma stem canker (blackleg) in summer before harvest. Due to the difficulties of investigating resistance to L. maculans growth in leaves and petioles under field conditions, identification of quantitative resistance typically relies on end of season stem canker assessment on adult plants. To investigate whether quantitative resistance can be detected in young plants, we first selected nine representative DH (doubled haploid) lines from an oilseed rape DY ('Darmor-bzh' × 'Yudal') mapping population segregating for quantitative resistance against L. maculans for controlled environment experiment (CE). We observed a significant correlation between distance grown by L. maculans along the leaf petiole towards the stem (r = 0.91) in CE experiments and the severity of phoma stem canker in field experiments. To further investigate quantitative trait loci (QTL) related to resistance against growth of L. maculans in leaves of young plants in CE experiments, we selected 190 DH lines and compared the QTL detected in CE experiments with QTL related to stem canker severity in stems of adult plants in field experiments. Five QTL for resistance to L. maculans growth along the leaf petiole were detected; collectively they explained 35% of the variance. Two of these were also detected in leaf lesion area assessments and each explained 10-12% of the variance. One QTL on A02 co-localized with a QTL detected in stems of adult plants in field experiments. This suggests that resistance to the growth of L. maculans from leaves along the petioles towards the stems contributes to the quantitative resistance assessed in stems of adult plants in field experiments at the end of the growing season.

Research paper thumbnail of Effects of cultivar resistance and fungicide application on stem canker of oilseed rape ( Brassica napus ) and potential interseasonal transmission of Leptosphaeria spp. inoculum

Plant Pathology, 2021

Phoma stem canker (also known as blackleg) is caused by two closely related coexisting ascomycete... more Phoma stem canker (also known as blackleg) is caused by two closely related coexisting ascomycete fungal pathogens, Leptosphaeria maculans and L. biglobosa (Fitt et al., 2006a; Shoemaker & Brun, 2001). This disease causes damage to oilseed rape worldwide (Fitt et al., 2006b) and accounts for annual yield losses to UK oilseed rape growers worth approximately £100 million, despite the use of fungicides and resistant cultivars (www.cropm onitor.co.uk) (Zhang et al., 2014). In the UK, phoma stem canker is a monocyclic disease that is initiated by ascospores as primary inoculum in autumn or winter. These ascospores are released from pseudothecia (sexual fruiting bodies) that mature after harvest on infected stem debris, such as stubble left in fields from the previous cropping season. Once mature, ascospores

Research paper thumbnail of Quantitative Trait Locus Mapping for Resistance Against Pyrenopeziza brassicae Derived From a Brassica napus Secondary Gene Pool

Frontiers in Plant Science, 2022

Use of host resistance is the most economical and environmentally safe way to control light leaf ... more Use of host resistance is the most economical and environmentally safe way to control light leaf spot disease of oilseed rape (Brassica napus). The causal organism of light leaf spot, Pyrenopeziza brassicae, is one of the most economically damaging pathogens of oilseed rape in the United Kingdom and it is considered to have a high potential to evolve due to its mixed reproduction system and airborne ascospores. This necessitates diverse sources of host resistance, which are inadequate at present to minimize yield losses caused by this disease. To address this, we screened a doubled haploid (DH) population of oilseed rape, derived from a secondary gene pool (ancestral genomes) of B. napus for the introgression of resistance against P. brassicae. DH lines were phenotyped using controlled-environment and glasshouse experiments with P. brassicae populations obtained from three different geographic locations in the United Kingdom. Selected DH lines with different levels of resistance wer...