Registration of sugar beet genetic stocks FC308 and FC309.

Sugar beet (Beta vulgaris L.) genetic stock lines FC308 (Reg. no. GS‐14, PI 701378) and FC309 (Reg. no. GS‐13, PI 700990) are two highly homozygous and phenotypically homogenous sources of resistance to two separate sugar beet pests. FC308 is resistant to sugar beet cyst nematode (SBCN) but is susceptible to Fusarium yellows (FY), whereas FC309 is FY resistant but SBCN susceptible. These two populations were developed by the USDA‐ARS in Fort Collins, CO, derived from unreleased USDA‐ARS Salinas germplasm lines 7927‐4‐308 and 7927‐4‐309. Multiple field and greenhouse trials for FY and nematode resistance confirmed the homogeneous phenotypic responses of both lines for each disease. To enable molecular breeders to rapidly screen proprietary markers in silico on these lines, gene space assemblies for individual plants from each line were also developed and are being released alongside these genetic stocks. Genome sequencing of individual plants from each line, as well as pooled sequencing of sub‐populations of both lines, indicated fixation of a previously reported genetic variant linked to SBCN resistance in FC308. However, two previously reported variants linked to Fusarium resistance appear to be unlinked to the resistance found in FC309. Collectively, these two new sugar beet genetic stock lines should prove useful as sources of resistance to FY and SBCN, as model genetic backgrounds for studying plant–pathogen interactions, and for mapping the causal resistance genes present in these lines. Core Ideas: Resistance traits for sugar beet cyst nematode and Fusarium yellows are fixed in FC308 and FC309, respectively.USDA‐ARS sugar beet pre‐breeding is shifting to molecular genetic and genomics‐guided approaches.Genomic resources being developed for FC308 and FC309 will aid in trait mapping and targeted introgression. [ABSTRACT FROM AUTHOR]