title: Fine mapping and candidate gene analysis of two loci conferring resistance to Phytophthora sojae in soybean.
abstract: RpsUN1 and RpsUN2 were fine mapped to two genomic regions harboring disease resistance-like genes. The haplotypes and instability of the regions and candidate genes for the two resistance loci were characterized. Phytophthora root and stem rot caused by Phytophthora sojae, is one of the most destructive diseases of soybean. Deploying soybean cultivars carrying race-specific resistance conferred by Rps genes is the most practical approach to managing this disease. Previously, two Rps genes, RpsUN1 and RpsUN2 were identified in a landrace PI 567139B and mapped to a 6.5 cM region on chromosome 3 and a 3.0 cM region on chromosome 16, corresponding to 1387 and 423 kb of the soybean reference genome sequences. By analyzing recombinants defined by genotypic and phenotypic screening of the 826 F2:3families derived from two reciprocal crosses between the two parental lines, RpsUN1 and RpsUN2, were further narrowed to a 151 kb region that harbors five genes including three disease resistance (R)-like genes, and a 36 kb region that contains four genes including five R-like genes, respectively, according to the reference genome. Expressional changes of these nine genes before and after inoculation with the pathogen, as revealed by RNA-seq, suggest that Glyma.03g034600 in the RpsUN1 region and Glyma.16g215200 and Glyma.16g214900 in the RpsUN2 region of PI 567139B may be associated with the resistance to P. sojae. It is also suggested that unequal recombination between/among R-like genes may have occurred, resulting in the formation of two recombinants with inconsistent genotypic and phenotypic observations. The haplotype variation of genomic regions where RpsUN1 and RpsUN2 reside in the entire soybean germplasm deposited in the US soybean germplasm collection suggests that RpsUN1 and RpsUN2 are most likely novel genes.
authors: College of Life Sciences, Qingdao Agricultural University, Qingdao, 266109, China.|Department of Agronomy, Purdue University, West Lafayette, IN, 47907, USA.
authors: Linghong
authors: L
authors: Li
authors: Department of Agronomy, Purdue University, West Lafayette, IN, 47907, USA.|Department of Plant, Soil and Microbial Sciences, Michigan State University, East Lansing, MI, 48824, USA.
authors: Feng
authors: F
authors: Lin
authors: Department of Agronomy, Purdue University, West Lafayette, IN, 47907, USA.
authors: Weidong
authors: W
authors: Wang
authors: Department of Agronomy, Purdue University, West Lafayette, IN, 47907, USA.|Bayer CropScience LP, Research Triangle Park, Durham, NC, 27709, USA.
authors: Jieqing
authors: J
authors: Ping
authors: Department of Agronomy, Purdue University, West Lafayette, IN, 47907, USA.
authors: Joshua C
authors: JC
authors: Fitzgerald
authors: Department of Agronomy, Purdue University, West Lafayette, IN, 47907, USA.|Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN, 47907, USA.
authors: Meixia
authors: M
authors: Zhao
authors: College of Life Sciences, Qingdao Agricultural University, Qingdao, 266109, China.
authors: Shuai
authors: S
authors: Li
authors: Department of Agronomy, Purdue University, West Lafayette, IN, 47907, USA.
authors: Lianjun
authors: L
authors: Sun
authors: College of Life Sciences, Qingdao Agricultural University, Qingdao, 266109, China. ccm@hotmail.com.
authors: Chunmei
authors: C
authors: Cai
authors: Department of Agronomy, Purdue University, West Lafayette, IN, 47907, USA. maj@purdue.edu.
authors: Jianxin
authors: http://orcid.org/0000-0002-1474-812X
authors: J
authors: Ma
mesh_terms: D002874:Chromosome Mapping; D060467:Disease Resistance / Q000235:genetics*; D017343:Genes, Plant; D056726:Genetic Association Studies; D005838:Genotype; D006239:Haplotypes; D010838:Phytophthora; D010935:Plant Diseases / Q000235:genetics / Q000382:microbiology; D017423:Sequence Analysis, RNA; D013025:Glycine max / Q000235:genetics* / Q000382:microbiology