Epigenetic regulation of Rhg1, a Soybean Cyst Nematode resistance locus
R. ZAPOTOCNY (1) (1) University of Wisconsin-Madison, U.S.A.

Soybean cyst nematode (SCN; Heterodera glycines) is the cause of an estimated $1.5 billion in damages in the U.S. annually. The primary source of resistance against SCN is Rhg1 (Resistance to Heterodera glycines). This 31kb locus contains four ORFs, of which three have been shown to contribute to resistance. Rhg1 exhibits copy number variation and is tandemly repeated up to ten times in resistant varieties. We recently reported differential Rhg1 locus methylation between SCN-resistant and SCN-susceptible varieties.  One hypothesis of the present project is that the repetitive nature of the locus promotes transcriptional gene silencing, resulting in decreased expression. Another is that the variable efficacy of Rhg1 in different genetic backgrounds is due in part to differential methylation between soybean varieties. A third hypothesis is that methylation is changing during the course of an infection resulting in altered expression of Rhg1 genes. To test these and related hypotheses, we have used McrBC to gain a baseline understanding of locus methylation as well as bisulfite sequencing and sRNA data, both courtesy of Kyung Do Kim and Scott Jackson.  To date, we observe significant differences in methylation levels between varieties but not between infection time points. We also observe methylation coincidence with increased presence of small RNA’s mapping to Rhg1. By determining how this very important locus is regulated we hope to assist efforts to improve SCN resistance. 

Abstract Number: P17-645
Session Type: Poster