Fungal pathogen of asparagus stem blight was isolated. No significant genetic difference was detected among the three strains with 492 bp long ITS1-5.8S-ITS2 sequence. It was then identified through colony growth, con...Fungal pathogen of asparagus stem blight was isolated. No significant genetic difference was detected among the three strains with 492 bp long ITS1-5.8S-ITS2 sequence. It was then identified through colony growth, conidia morphology, and molecular characterization. The physiological response to oxidation and osmosis stress, and virulence to Asparagus officinalis L. were analyzed. The results showed that the pathogen causing asparagus stem blight for A. officinalis L. in Jiangxi Province is Phomopsis asparagri (Sacc.) Bubák. Under pure culture conditions, the conidia were oval-shaped (α-type), with colorless single spore and single nucleus, containing 0-2 oil balls. Its vegetative growth rate was higher when cultured on 0.2 × potato dextrose agar (0.2 × PDA) medium than that on oatmeal agar (OA) medium. However, the pycnidia appeared earlier on OA medium than on 0.2 earlier PDA medium. The vegetative growth rate was depressed under oxidation (H2O2) or osmosis (NaCl) stress conditions, and totally inhibited under 7 mmol/L H2O2 or 2.4 mol/L NaCl. All the strains caused typical pathogenic symptoms to Asparagus officinalis L. at 7 days-post-inoculation (dpi) with conidia.展开更多
L. albus is an annual grain-legume crop mainly grown for high-protein fodder worldwide but also to produce large seeds for human consumption as a snack-food. In order to make genetic gains in grain yield, assessment o...L. albus is an annual grain-legume crop mainly grown for high-protein fodder worldwide but also to produce large seeds for human consumption as a snack-food. In order to make genetic gains in grain yield, assessment of the genetic variation in the germplasm and identification of loci associated with agronomic traits are essential. Phomopsis blight (PB) and Pleiochaeta root rot (PRR), caused by the fungal pathogens Diaporthe toxica and, Pleiochaeta setosa respectively, are two major yield-limiting diseases of the L. albus crop. The extent of genetic diversity in 94 accessions of L. albus comprising: Australian and exotic cultivars, advanced breeding lines, and landraces originating from 26 different countries was determined utilizing PCR-based genic, and microarray-based Diversity Arrays Technology (DArT™), markers. All accessions were evaluated for resistance to PB in two plant tissues (leaves and stems) using either sprayed or injected spore inoculum. A subset of 58 accessions was further evaluated for resistance to PRR by growing seedlings in spore-infested potting mix. The combined data of 724 (50 genic- and 674 DArT) markers were used for cluster analysis. A subset of 324 markers with call rate ≥95% and predicted disease scores of different genotypes were used to identify marker loci accounting for phenotypic variation in PB and PRR resistance using linear regression analysis. Several markers showed significant association with PB or PRR resistance at P < 0.05. Our results showed that favourable alleles for PB and PRR resistance are present in the diverse accessions investigated and they will provide valuable materials for lupin breeding.展开更多
文摘Fungal pathogen of asparagus stem blight was isolated. No significant genetic difference was detected among the three strains with 492 bp long ITS1-5.8S-ITS2 sequence. It was then identified through colony growth, conidia morphology, and molecular characterization. The physiological response to oxidation and osmosis stress, and virulence to Asparagus officinalis L. were analyzed. The results showed that the pathogen causing asparagus stem blight for A. officinalis L. in Jiangxi Province is Phomopsis asparagri (Sacc.) Bubák. Under pure culture conditions, the conidia were oval-shaped (α-type), with colorless single spore and single nucleus, containing 0-2 oil balls. Its vegetative growth rate was higher when cultured on 0.2 × potato dextrose agar (0.2 × PDA) medium than that on oatmeal agar (OA) medium. However, the pycnidia appeared earlier on OA medium than on 0.2 earlier PDA medium. The vegetative growth rate was depressed under oxidation (H2O2) or osmosis (NaCl) stress conditions, and totally inhibited under 7 mmol/L H2O2 or 2.4 mol/L NaCl. All the strains caused typical pathogenic symptoms to Asparagus officinalis L. at 7 days-post-inoculation (dpi) with conidia.
文摘L. albus is an annual grain-legume crop mainly grown for high-protein fodder worldwide but also to produce large seeds for human consumption as a snack-food. In order to make genetic gains in grain yield, assessment of the genetic variation in the germplasm and identification of loci associated with agronomic traits are essential. Phomopsis blight (PB) and Pleiochaeta root rot (PRR), caused by the fungal pathogens Diaporthe toxica and, Pleiochaeta setosa respectively, are two major yield-limiting diseases of the L. albus crop. The extent of genetic diversity in 94 accessions of L. albus comprising: Australian and exotic cultivars, advanced breeding lines, and landraces originating from 26 different countries was determined utilizing PCR-based genic, and microarray-based Diversity Arrays Technology (DArT™), markers. All accessions were evaluated for resistance to PB in two plant tissues (leaves and stems) using either sprayed or injected spore inoculum. A subset of 58 accessions was further evaluated for resistance to PRR by growing seedlings in spore-infested potting mix. The combined data of 724 (50 genic- and 674 DArT) markers were used for cluster analysis. A subset of 324 markers with call rate ≥95% and predicted disease scores of different genotypes were used to identify marker loci accounting for phenotypic variation in PB and PRR resistance using linear regression analysis. Several markers showed significant association with PB or PRR resistance at P < 0.05. Our results showed that favourable alleles for PB and PRR resistance are present in the diverse accessions investigated and they will provide valuable materials for lupin breeding.
