Narrative
A beet plant can have thousands of flowers making traits highly heterogenous. For mapping population development and genetic studies, resistance must be confirmed prior to crossing, or progeny could have unexpected segregation. All parental lines were grown in SBCN-infested soil (20 Heterodera schachtii cysts/g soil) in the greenhouse to identify resistant (low cyst count) and susceptible (high cyst count) individuals. Crosses were made with selected individuals of known SBCN reaction. One SBCN-resistant donor parent for population CN240 was 7927-4-308D (USDA-ARS unreleased) and the other was CN12-446 (USDA-ARS PI 657939). 7927-4-308D is an S1 progeny selected from C927-4 (PI 628756) with resistance to H. schachtii. It is a multigerm (MM), self-fertile (Sf) diploid that segregates for genetic male sterility (A_:aa), hypocotyl color (R_:rr), and resistance to rhizomania (caused by Beet necrotic yellow vein virus) conferred by Rz1. 7927-4-308D is resistant to SBCN and susceptible to Fusarium stalk blight (Fusarium oxysporum Schltdl.). According to its pedigree, SBCN resistance in 7927-4-308D is derived from C51 (PI 593694), a composite cross between sugar beet and over 40 Bvm accessions, which currently makes it impossible to determine the exact accession that provided the SBCN resistance. CN12-446 confers SBCN resistance from PI 546413 (Bvm accession WB 242, HsBvm-1) and was derived from CN12 (PI 636338) (Richardson, 2012). CN12-446 is a multigerm (MM), green hypocotyl (rr), and self-fertile (Sf) line that segregates for genetic male sterility (A-: aa) with resistance to powdery mildew (Erysiphae polygoni DC.). The allelism between 7927-4-308D and CN12-446 is undetermined, but PI 546413 is one of the 40 Bvm accessions in C51 (Richardson, 2018). The SBCN-resistant donor parent for population CN239 was 7927-4-308D (USDA-ARS unreleased) and the susceptible parent was 0747 (USDA-ARS PI 590762). 7927-4-308D is an S1 progeny selected from C927-4 (PI 628756) with resistance to H. schachtii. It is a multigerm (MM), self-fertile (Sf) diploid that segregates for genetic male sterility (A_:aa), hypocotyl color (R_:rr), and resistance to rhizomania (caused by Beet necrotic yellow vein virus) conferred by Rz1. 7927-4-308D is resistant to SBCN and susceptible to Fusarium stalk blight (Fusarium oxysporum Schltdl.). According to its pedigree, SBCN resistance in 7927-4-308D is derived from C51 (PI 593694), a composite cross between sugar beet and over 40 Bvm accessions, which currently makes it impossible to determine the exact accession that provided the SBCN resistance. 0747 is a self-fertile (Sf) parental line segregating for genetic male sterility (A-: aa). 0747 is susceptible to SBCN and resistant to beet curly top (Beet curly top virus), bolting, virus yellows (Beet yellows virus and Beet western yellows virus), and bacterial vascular necrosis and rot (Pectobacterium betavasculorum (Thomson et al., 1981) Gardan et al., 2003 (syn. Erwinia carotovora subsp. betavasculorum). 0747 is a self-fertile version of C37 (PI 590715) (Lewellen et al., 1985).The SBCN-resistant donor parent for population CN241 was 7927-4-308D (USDA-ARS unreleased) and the susceptible parent was 7927-4-309E (USDA-ARS unreleased). 7927-4-308D is an S1 progeny selected from C927-4 (PI 628756) with resistance to H. schachtii. It is a multigerm (MM), self-fertile (Sf) diploid that segregates for genetic male sterility (A_:aa), hypocotyl color (R_:rr), and resistance to rhizomania (caused by Beet necrotic yellow vein virus) conferred by Rz1. 7927-4-308D is resistant to SBCN and susceptible to Fusarium stalk blight (Fusarium oxysporum Schltdl.). According to its pedigree, SBCN resistance in 7927-4-308D is derived from C51 (PI 593694), a composite cross between sugar beet and over 40 Bvm accessions, which currently makes it impossible to determine the exact accession that provided the SBCN resistance. 7927-4-309E is an S1 progeny selected from C927-4 (PI 628756) that is susceptible to H. schachtii. It is a multigerm (MM), self-fertile (Sf) diploid that segregates for genetic male sterility (A_:aa), hypocotyl color (R_:rr), and resistance to rhizomania (caused by Beet necrotic yellow vein virus) conferred by Rz1. 7927-4-309E is susceptible to SBCN and resistant to Fusarium stalk blight.