Bhupendra Acharya, Sungwoo Lee, M. A. Rouf Mian, Tae-Hwan Jun, Leah K. McHale, Andrew P. Michel, Anne E. Dorrance

Theoretical and Applied Genetics, May 2015, Volume 128, Issue 5, pp 827-838

http://link.springer.com/article/10.1007/s00122-015-2473-5

Abstract

Key message

A major novel QTL was identified in a recombinant inbred line population derived from a cross of ‘Wyandot’ × PI 567301B for Fusarium graminearum, a seed and seedling pathogen of soybean.

Abstract

Fusarium graminearum is now recognized as a primary pathogen of soybean, causing root, seed rot and seedling damping-off in North America. In a preliminary screen, ‘Wyandot’ and PI 567301B were identified with medium and high levels of partial resistance to F. graminearum, respectively. The objective of this study was to characterise resistance towards F. graminearum using 184 recombinant inbred lines (RILs) derived from a cross of ‘Wyandot’ × PI 567301B. The parents and the RILs of the mapping population were evaluated for resistance towards F. graminearum using the rolled towel assay in a randomized incomplete block design. A genetic map was constructed from 2545 SNP markers and 2 SSR markers by composite interval mapping. One major and one minor QTL were identified on chromosomes 8 and 6, respectively, which explained 38.5 and 8.1 % of the phenotypic variance. The major QTL on chromosome 8 was mapped to a 300 kb size genomic region of the Williams 82 sequence. Annotation of this region indicates that there are 39 genes including the Rhg4 locus for soybean cyst nematode (SCN) resistance. Based on previous screens, PI 567301B is susceptible to SCN. Fine mapping of this locus will assist in cloning these candidate genes as well as identifying DNA markers flanking the QTL that can be used in marker-assisted breeding to develop cultivars with high levels of resistance to F. graminearum.

Fig. 2  Graphical presentation of quantitative trait loci (QTL) for resistance to Fusarium graminea rumidentified on chromosome a8 and b6 in the ‘Wyandot’ ×PI 567301B population by genome-wide LOD threshold 3.4 (a hatched linein LOD plots). The 1- and 2-LOD intervals are presented by a black barand solid linesbetween the chromosome and the LOD plot for each QTL. The enlarged image was presented side by side to highlight approximate 20 cM region around LOD peak of each QTL