Epistatic interaction between Rhg1-a and Rhg2 in PI 90763 confers resistance to virulent soybean cyst nematode populations

Pawan Basnet, Clinton G. Meinhardt, Mariola Usovsky, Jason D. Gillman, Trupti Joshi, Qijian Song, Brian Diers, Melissa G. Mitchum, Andrew M. Scaboo

Research output: Contribution to journalArticlepeer-review

Abstract

Key message: An epistatic interaction between SCN resistance loci rhg1-a and rhg2 in PI 90,763 imparts resistance against virulent SCN populations which can be employed to diversify SCN resistance in soybean cultivars. Abstract: With more than 95% of the $46.1B soybean market dominated by a single type of genetic resistance, breeding for soybean cyst nematode (SCN)-resistant soybean that can effectively combat the widespread increase in virulent SCN populations presents a significant challenge. Rhg genes (for Resistance to Heterodera glycines) play a key role in resistance to SCN; however, their deployment beyond the use of the rhg1-b allele has been limited. In this study, quantitative trait loci (QTL) were mapped using PI 90,763 through two biparental F3:4 recombinant inbred line (RIL) populations segregating for rhg1-a and rhg1-b alleles against a SCN HG type 1.2.5.7 (Race 2) population. QTL located on chromosome 18 (rhg1-a) and chromosome 11 (rhg2) were determined to confer SCN resistance in PI 90,763. The rhg2 gene was fine-mapped to a 169-Kbp region pinpointing GmSNAP11 as the strongest candidate gene. We demonstrated a unique epistatic interaction between rhg1-a and rhg2 loci that not only confers resistance to multiple virulent SCN populations. Further, we showed that pyramiding rhg2 with the conventional mode of resistance, rhg1-b, is ineffective against these virulent SCN populations. This highlights the importance of pyramiding rhg1-a and rhg2 to maximize the impact of gene pyramiding strategies toward management of SCN populations virulent on rhg1-b sources of resistance. Our results lay the foundation for the next generation of soybean resistance breeding to combat the number one pathogen of soybean.

Original languageEnglish (US)
JournalTheoretical and Applied Genetics
DOIs
StateAccepted/In press - 2022

ASJC Scopus subject areas

  • Biotechnology
  • Agronomy and Crop Science
  • Genetics

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