Registration of 40 Converted Germplasm Sources from the Reinstated Sorghum Conversion Program

Abstract

Forty sources of late‐maturing sorghum [ Sorghum bicolor (L.) Moench] germplasm registered with the National Plant Germplasm System as genetic stocks (Reg. No. GS‐744, PI 674473 to Reg. No. GS‐783, PI 674512) were converted to early‐maturing, dwarf‐height BC 1 F 3 families and released by the National Sorghum Foundation, the United Sorghum Checkoff Program, the USDA‐ARS, and NuSeed/MMR Genetics in 2014. The sorghum working groups represented include zerazera, caudatum, conspicuum, durra, nandyal, nigricans, guineense, caudatum‐kafir, caudatum‐guineense, caudatum‐nigricans, caudatum‐durra, durra‐kafir, durra‐bicolor, caffrorum‐bicolor, and durra‐dochna. Conversion was accomplished by crossing late‐maturing tropical accessions to inbred BTx406 in a short‐day nursery with selection of early‐maturing, short genotypes within F 2 segregating populations in a long‐day nursery. Early‐flowering short F 2 selections were genotyped, and one F 2 plant with the greatest proportion of the exotic genome from each accession was backcrossed to the plant introduction. The resulting BC 1 F 1 was self‐pollinated, and selections of early‐maturing, short genotypes within BC 1 F 2 segregating populations were made. Early‐flowering, short BC 1 F 2 selections were genotyped, and one BC 1 F 2 plant with the greatest proportion of the exotic genome was self‐pollinated. The BC 1 F 2:3 families, RSC02‐BC 1 ‐10‐F 3 bk to RSC149‐BC 1 ‐12‐F 3 bk, represent new sources of germplasm from the USDA‐ARS sorghum collection readily usable in temperate zones worldwide.