OBJECTIVE 1 - Characterize Cercospora sojina (FLS pathogen) and Cercospora flagellaris population diversity and race structure:
We expect to complete the genotype-by-sequencing analyses on larger populations of C. sojina and C. flagellaris, and to identify candidate genes/genomic regions underlying race structure in C. sojina. The completion of the proposed work will result in the generation of genomic tools to study C. sojina and C. flagellaris, and in the identification of genes or gene variants unique to specific races of C. sojina and C. flagellaris. The information generated will help develop more efficient variety screening programs for breeders that rely more on the use of molecular markers. This will alleviate the current need in breeding programs for extensive phenotyping using plant differentials, which is very time consuming and labor intensive.
OBJECTIVE 2 - Management of Cercospora Leaf Blight of soybean with foliar applications of minor elements and development of a disease resistance screening protocol.
This research will ultimately lead to the delivery of recommendations for optimum tissue levels of iron and other minor elements to manage CLB. By the conclusion of the proposed experiments, we will be able to accurately identify iron and other minor element tissue concentrations associated with disease suppression. We will also be able to identify those compounds in soybean associated with anti-oxidant activity and disease resistance. Moreover, leaf culture protocols will be finalized and recommendations will be handed off to plant breeders.
OBJECTIVE 3 - Conduct extensive monitoring for fungicide-resistant strains of C. sojina, and C. flagellaris, and Septoria glycines and develop and adapt fungicide application strategies accordingly:
By the end of the proposed research, an initial survey of strobilurin-fungicide-resistant strains of C. sojina, C. flagellaris, and S. glycines across the participating states will be completed. Furthermore, fungicide recommendations to manage C. sojina and C. flagellaris will be updated taking into consideration the distribution of fungicide- resistant strains.
OBJECTIVE 4 - Identify sources of resistance and develop resistant varieties and elite germplasm for C. sojina and C. flagellaris:
A collection of commercial varieties and public lines (plant introductions and advanced breeding lines) will be screened in the greenhouse and in the in the field for resistance to frogeye leaf spot and to Cercospora leaf blight. Mapping populations will be developed. Advanced breeding lines with resistance to FLS will be introduced to multi-location yield trials to select those lines that combine resistance with high crop potential. An expanded multi-state regional field trial will evaluate an increased number of lines and varieties to identify lines with stable CLB resistance across locations. Crosses will be made with CLB resistant lines to incorporate resistance into elite lines and varieties. Mapping populations will be phenotyped and genotyped with SSR and SNP markers to map novel FLS resistance genes.
OBJECTIVE 5 - Determine the effect of Soybean Vein Necrosis Virus (SVNV) on yield and evaluate soybean germplasm for resistance to thrips and SVNV:
The completion of this objective will benefit growers and crop advisors that are affected by SVNV, by being able to equate the level of severity of visual symptoms with potential yield loss and thus make more informed decisions about the need for control measures. In addition to providing an estimate of the effect of SVNV incidence on yield, we will be generating and publishing at last one report related to the evaluation of soybean germplasm for resistance to thrips and SVNV.