Factors affecting tissue culture initiation from maize tassels

Abstract

Totipotent tissue cultures of maize ( Zea mays L.) previously have been initiated from various explant tissues, including immature tassels. To obtain high frequencies of culture initiation from immature tassels, we recommend the use of tassels between 1 and 3 cm long, cut into 1-mm sections, and incubation under low light on Murashige and Skoog (MS) medium containing 1.0 mg/1 2,4-dichlorophenoxyacetic acid (2,4-D). Callus with opaque white structures resembling embryonic scutella was classified as totipotent (capable of plant regeneration). Frequencies of tassels which produced one or more of these totipotent cultures ranged from 0 to 100% among 13 genotypes. Ten of these 13 genotypes produced cultures from at least 20% of their explanted tassels. Not all cultures classified as totipotent were capable of producing plants which would grow to maturity. The responses of reciprocal F 1 genotypes and their parental lines suggested that partially dominant nuclear genes control culture initiation. No evidence of cytoplasmic or maternal effects was found. Within genotypes, responses of immature embryos and tassels in vitro were similar qualitatively and quantitatively, and thus appeared to be under similar genetic control. The use of immature tassels as explants permits selection of specific genotypes via genetic markers or particular plant phenotypes prior to culture initiation.