Abstract
The effects of cold pretreatment of inflorescences (1, 2, or 3 weeks at 4°C), different carbon sources (sucrose, glucose, maltose, galactose and mannitol) and two gelling agents (agar at 0.7% and Gelrite at 0.25%) were investigated for their effects on callus formation and somatic embryogenesis in anther tissues of Vitis vinifera L., cvs. Regina and Reichensteiner. In cv. Regina, cold pretreatment for 2 weeks promoted development of more embryogenic explants, improved embryogenic efficiency and increased the number of germinated somatic embryos compared with 1, or 3 weeks cold pretreatment. Sucrose produced the highest callus formation followed by sucrose + mannitol, glucose and maltose. Mannitol did not support callus formation. Somatic embryogenesis occurred on the sucrose-and glucose-supplemented media. In cv. Reichensteiner, carbon source also significantly affected callus formation and somatic embryogenesis, which again occurred on sucrose- and glucose-supplemented media, However, embryogenic efficiency and embryo germination were higher among embryos cultured on glucose medium than on sucrose medium. The type of gelling agent did not have a significant impact on callus formation in cv. Reichensteiner during 4 weeks of culture in the dark. Anthers cultured on agar, or Gelrite produced somatic embryos with a similar embryogenic efficiency. In all of these experiments, normal and abnormal somatic embryos were obtained.