Ethidium Bromide-induced Mutations from Inflorescence Cultures of Indiangrass

Abstract

Immature inflorescences of a Sorghastrum nutans (L.) Nash selection were cultured on CCm medium with 5 mg·L−1 2,4-dichlorophenoxyacetic acid and 1 mg·L−1 N6-benzyladenine (BA) for 5 weeks. Callused inflorescence cultures were placed on CCm medium with 1 mg·L−1 BA (CCmB1) and 0 or 250 mg·L−1 ethidium bromide (EtBr) for 24 h. Cultures were transferred to CCmB1 without EtBr for shoot regeneration and then to CCm without plant growth regulators for rooting. Rooted shoots were transferred to soil under greenhouse conditions and then to the field. Fifteen putative M1 mutants with atypical phenotypes were detected among 71 EtBr-treated regenerants. Two self-incompatible putative M1 mutants were progeny-tested by using a wild-type Indiangrass seedling as the pollen parent. M1 selection ISU06-35 was a dwarf mutant whose M2 testcross progeny segregated 1:1 tall:dwarf seedlings. M1 selection ISU06-56 was a red-flowered mutant whose M2 testcross progeny segregated 1:1 green-flowered:red-flowered seedlings. These results are consistent with both M1 mutants being dominant nuclear mutations.