Annotation of the Rhg4 Region of Cultivar Forrest Soybean

Soybean (Glycine max (L. Merr.)) resistance to certain  populations of  Heterodera glycines (I.), required a functional allele at Rhg4. H. glycines, the soybean cyst nematode (SCN) was an ancient, endemic, pest of soybean. The Rhg4 locus for resistance to SCN in  cultivar Forrest was derived from Peking a semi-domesticated soybean. Williams 82 and Asgrow 3244 are both susceptible cultivars. The BAC B100B10 was sequenced by Snager sequencing and compared to the susceptibles.  Many (750)  insertions and deletions were found in Forrest compared to both susceptible cultivars. The percentage of As and Ts in each deletion and the percentage of Gs and Cs in each deletion were more AT rich than GC rich. Longer insertions and deletions were found in  protein coding region (96749 – 101558 bp). There was a three base pair deletion in Forrest that altered two codons. Out of the 1603 amino acids in this protein, nineteen amino acids were deleted from Forrest and so associated with resistance  to SCN. Moreover, sixteen of the nineteen deleted amino acids were hydrophobic. This suggests that this protein lies somewhere in one of the membranes in the cells of the soybean plant. Therefore, Rhg4 was inferred to be multigenic at located within a hot-spot for indels.