SOMATIC EMBRYOGENESIS AND PLANT-REGENERATION FROM IMMATURE INFLORESCENCES OF SEVERAL ELITE INBREDS OF MAIZE

Somatic embryogenesis and plant regeneration was obtained from immature inflorescence segments of maize (Zea mays L.). Immature tassels and ears (0.5-3.0 cm) were excised, cut into segments (1 - 2 mm), and place onto media supplemented with varying concentrations of 2,4-dichlorophenoxyacetic acid (2,4-D), sucrose and l-proline. After 2-3 weeks, the segments produced compact, nodular, white, embryogenic callus as well as soft, granular, friable, non-embryogenic callus. Embryogenic callus further developed somatic embryos with distinct scutellar- and coleoptile-like structures, which produced normal, fertile plants with no apparent morphological abnormalities. Maximum embryogenic callus formation was observed when segments, cut from 0.6-1.0 cm inflorescences, were cultured on Murashige and Skoog (MS) medium with 2 mg/l 2,4-D, 3% sucrose, and 24 mM l-proline. Although embryogenic callus production was observed in all inbreds tested, significant genotype effects were apparent. The inbreds A619, H99, LH39, LH39, MBS501, MS71, Oh43, U94 and U98 all displayed high frequencies of embryogenic callus production (45-80% of cultured segments) and plant regeneration (up to 50% of callus pieces transferred). Thus, immature inflorescences can be used as explants for high frequency somatic embryogenesis and plant regeneration from several commercially-important maize inbreds. © 1990.