Mapping Phytophthora Resistance Loci in Soybean with Restriction Fragment Length Polymorphism Markers

Abstract

Phytophthora root rot, caused by Phytophthora megasperma Drechs. f. sp. glycinea T. Kuan & D.C. Erwin, is one of the most serious diseases of soybean [Glycine max (L.) Merr.]. Six loci with alleles giving race‐specific resistance of soybean to phytophthora have been reported. The first objective of this study was to map the phytophthora resistance (Rps) loci using restriction fragment length polymorphism (RFLP) markers. The second objective was to map the Rj2 locus for ineffective nodulation with RFLP markers, because of the linkage of Rj2 to Rps2. The mapping was conducted using a series of ‘Williams’ near‐isogenic lines (NILs) with each having one or two phytophthora resistance alleles. The NILs were screened with 141 mapped RFLP markers. At least one polymorphism was found between each NIL and the recurrent parent. Linkage tests among the polymorphic RFLP markers, Rps loci, and the RJ2 locus were conducted using F2 populations. Linkage was found between RFLP markers and Rpsl, Kps2, Rps3, Rps4, Rps5, and RJ2. Linkage was also found between Rps2 and Rj2.

Deletion of a Disease Resistance Nucleotide-Binding-Site Leucine-Rich- Repeat-like Sequence Is Associated With the Loss of the Phytophthora Resistance Gene Rps4 in Soybean

“…were mapped into the slits (Schmitthenner et al 1994). Resistant and sus-to the Rps3 locus (Diers et al 1992 Pathogen used: P. sojae races 1 and 4 and isolates I-CC5A, I-CC5C, I-CC8, I-CC9A, I-CC10D, I-CE5, I-CE10, I-CE20, I-CW1, has not been consistent in previous studies (Athow and races (Buzzell et al 1987). …”

Genetic Linkage Between Isozyme, Morphological, and DNA Markers in Tepary Bean

“…(Keim et al 1990), cowpea (Vigna unguiculata), and mung bean (Vigna radiatd) (Fatokun et al 1992). Although most of these maps have been generated only recently, they already have proven useful for identifying molecular markers for commercially important monogenic traits (Diers et al 1992) and for analyzing the genetic basis of more complex characters (Fatokun et al 1992;Keim et al 1990).…”

Resistance gene analogs are conserved and clustered in soybean

“…The RGA loci mapped both singly and in clusters and were located on several of the linkage groups to which known disease resistance genes have been mapped. A class 6 RGA mapped to linkage group Ni near Rps1 (35). A large cluster of RGAs representing five of the different classes mapped to linkage group J and encompassed a resistance gene cluster including Rmd, Rps2, and Rj2 (32) composite map shown in Fig.…”

“…Primer sequences were as follows: LM638, 5'-GGIGGIGTIG-GIAAIACIAC-3', and LM637, 5' -A(A/G)IGCTA(A/ G)IGGIA(A/G)ICC-3'. PCR was performed in a total volume of 100 ,ul, with a 3-min initial denaturation step at 94°C followed by 35 *To whom reprint requests should be addressed.…”