This project was initiated preceding the incorporation and standardization of KPIs. The progress of objectives are as follows:
Achieving the objectives:
• Many new lines and progenies were advanced in the summer of 2014 and will continue in 2015. The have included combining charcoal rot and frogeye leaf spot resistance with nematode resistance.
• Other lines with potentially novel SCN resistance sources were planted for further evaluation. Five advanced lines were entered into Uniform regional tests and 25 lines were selected for further testing in Iowa.
• New germplasm lines released: IAR2601 SCN. High-yielding conventional cultivar of MG II, resistance to SCN derived from PI 88788 and Peking. AR11SDS was registered (it is a germplasm line resistant to SDS, SCN and iron deficiency chlorosis.
• A manuscript for publication was accepted in Crop Science (2015) on new soybean PI lines identified for their resistance to SCN.
• Approximately 400 lines have been screened for resistance to SCN Race 2 and 3.
• SNP markers for B1 and O loci were developed. Fine mapping of the B1 locus (from PI 437654) is ongoing.
• RILS of Magellan x PI404198B were tested for reniform resistance.
• Populations were advanced to develop diagnostic markers and fine mapping for resistance to M. javanica and M. arenaria. F5 derived RILs from PI 200538 X CNS and PI 594427C X CNS in 2014 to fine map the QTL for resistance to M. javanica and M. arenaria were harvested. 100 F5:6 RILs from the cross of PI 200538 x CNS (susceptible to both Ma and Mj) each with 6 replicates were planted and genotyped with two SNP markers flanking 680kb region to identify the recombination events. Nine out of 100 RILs possessed recombination break points. 23 polymorphic SNP markers were designed based on SoySNP50K haplotypes and will be used for further genotyping to identify recombinant events. Similarly, to fine map the major QTL conditioning Mj resistance, 100 F5:6 RILs from the cross of PI 594427C x CNS were planted and the identification of recombinant events is underway. The phenotyping for both populations are in progress.
• Work to develop markers for SCN haplotypes (PI 88788, Peking and susceptible) at Rhg1 and Rhg4 is completed. A strong correlation between SNP haplotypes and reactions to SCN race 3 was observed based on a panel of 153 soybean lines from previous three years USDA Uniform Soybean Tests for Southern States. A few lines did not show a correlation between the expected phenotypes and the resistance SNP alleles. We have designed a study to understand why these lines with the resistance SNP genotypes did not have a resistance reaction to SCN race 3. A publication detailing the assays is under revision.
• Crosses using G. tomentella as the female parent were derived. All previous lines had it as the male parent. Retesting of F2 lines that were resistant in the first tests have shown that 2 of the lines are not resistant. One line may have some useable resistance and additional testing is underway with a new nematode population. None the less the researchers still have a significant number of lines that appear to show more resistance than the resistant soybean parent, Dwight.
Not achieving objectives:
• None at this time.