Relationship between initiation of embryogenic suspensor mass (ESM) and zygotic embryo development in Pinus densiflora

摘要

To initiate embryogenic suspensor mass (ESM) in Pinus densiflora , immature seeds were collected on dates from 31 May to 20 July in 2004, 2005 and 2006, and their embryo developmental stages were checked. In materials from 2004, the highest frequency (0.88%) of ESM initiation was obtained with explants collected on 28 June, and the seeds contained zygotic embryos in the proembryo stage (100%). The highest ESM initiation frequencies were 0.88% (28 June 2004, Suwon), 1.4% (1 July 2005, Suwon), 2.31% (1 July 2005, Anmyeondo) and 0.91% (1 July 2006, Suwon) and all embryos were at the proembryo stage, regardless of seed collection year (2004, 2005 or 2006) or collection location (Suwon or Anmyeondo). Histological analysis from zygotic embryos (proembryos) of seeds, which were harvested at various times or locations, revealed no significant morphological differences at various developmental stages. These results show that seed collection time could be critical for obtaining the higher rate of ESM initiation.