Development and dissection of diagnostic SNP markers for the downy mildew resistance genes PlArgand Pl8and maker-assisted gene pyramiding in sunflower (Helianthus annuus L.).
Diagnostic DNA markers are an invaluable resource in breeding programs for successful introgression and pyramiding of disease resistance genes. Resistance to downy mildew (DM) disease in sunflower is mediated by Pl genes which are known to be effective against the causal fungus, Plasmopara halstedii. Two DM resistance genes, PlArgand Pl8, are highly effective against P. halstedii races in the USA, and have been previously mapped to the sunflower linkage groups (LGs) 1 and 13, respectively, using simple sequence repeat (SSR) markers. In this study, we developed high-density single nucleotide polymorphism (SNP) maps encompassing the Plargand Pl8genes and identified diagnostic SNP markers closely linked to these genes. The specificity of the diagnostic markers was validated in a highly diverse panel of 548 sunflower lines. Dissection of a large marker cluster co-segregated with PlArgrevealed that the closest SNP markers NSA_007595 and NSA_001835 delimited PlArgto an interval of 2.83 Mb on the LG1 physical map. The SNP markers SFW01497 and SFW06597 delimited Pl8to an interval of 2.85 Mb on the LG13 physical map. We also developed sunflower lines with homozygous, three gene pyramids carrying PlArg, Pl8, and the sunflower rust resistance gene R12using the linked SNP markers from a segregating F2population of RHA 340 (carrying Pl8)/RHA 464 (carrying PlArgand R12). The high-throughput diagnostic SNP markers developed in this study will facilitate marker-assisted selection breeding, and the pyramided sunflower lines will provide durable resistance to downy mildew and rust diseases.
Northern Crop Science Laboratory, USDA-Agricultural Research Service, 1605 Albrecht Blvd N, Fargo, ND, 58102-2765, USA. lili.qi@ars.usda.gov.
L L
http://orcid.org/0000-0002-9787-8156
LL
Qi
Department of Plant Sciences, North Dakota State University, Fargo, ND, 58108, USA.
Z I
ZI
Talukder
Northern Crop Science Laboratory, USDA-Agricultural Research Service, 1605 Albrecht Blvd N, Fargo, ND, 58102-2765, USA.
B S
BS
Hulke
Northern Crop Science Laboratory, USDA-Agricultural Research Service, 1605 Albrecht Blvd N, Fargo, ND, 58102-2765, USA.
M E
ME
Foley
D002874:Chromosome Mapping; D060467:Disease Resistance / Q000235:genetics*; D017343:Genes, Plant / Q000235:genetics; D005819:Genetic Markers / Q000235:genetics; D005838:Genotype; D006368:Helianthus / Q000235:genetics*; D009868:Oomycetes / Q000472:pathogenicity*; D010935:Plant Diseases / Q000382:microbiology*; D020641:Polymorphism, Single Nucleotide / Q000235:genetics*
D005819:Genetic Markers
Clustered marker dissection; Diagnostic SNP marker; Downy mildew disease; Resistance gene pyramiding; Sunflower