Dedifferentiating initiation and embryogenesis from freshly-isolated microspores of barley

By using DNA-specific fluorescent dye and a confocal laser scanning microscope, the present study was designed to investigate the cytological characteristics of dedifferentiating initiation during pretreatment and embryogenesis during culture in freshly-isolated microspores of barley, and the difference in main developmental pathway between freshly-isolated and cold-treated microspores. The results revealed that (i) freshly-isolated microspores started the initiation within 12 h of mannitol pretreatment, whose main cytological characteristics were that: cell volume was obviously extended; the volume of nuclei and nucleoli were also greatly increased; nucleoli were extremely clear and highly condensed; N/C ratio was very high; (ii) all the pretreatment methods led to the initiation of the microspores, thus triggering the embryogenic process; (iii) pretreatment methods influenced the main developmental pathway of microspores by changing the pattern of the first mitosis. The cold-treated microspores formed main developmental pathway via A patterns, but freshly-isolated microspores via B pattern.