Anatomical and histochemical characterization of seeds of Cattleya intermedia subjected to different storage conditions

Abstract Studies involving morphological and anatomical changes resulting from seed storage are rare, but relevant to ensure information related to the quality of seeds and seedlings originated from these seeds. The objectives of this work as to carry out the anatomical and histochemical characterization of seeds from the Cattleya intermedia orchid, verifying the occurrence of possible alterations coming from different temperatures and storage periods. The treatments consisted of temperatures of: 25 (± 2 °C) (room), -20 °C (freezer), -80 °C (ultra freezer) and - 196 °C (cryopreservation); and storage periods: two, four and six months. For the anatomical and histochemical analyses, scanning electron microscopy and light microscopy were performed. The following stains were employed: toluidine blue (TBO), Coomassie brilliant blue (CBB), Sudan IV and periodic acid-Schiff (PAS). The dehydration observed in the seeds was considered the main damage resulting from storage. Changes in the internal structures of the seeds were also noted, such as degeneration, mainly in seeds kept at room temperature 25 (± 2 °C), which caused a reduction in the main components of reserves. The -80 °C (ultra freezer) temperature during the two and four months period was efficient in the conservation seed of the tissues and cells, confirming the possibility of using this condition for better conservation of the seeds of this species.

摘要 针对种子贮藏所引发的形态与解剖学变化的相关研究较为少见，但此类研究对于明晰由该类种子培育的种子及幼苗的品质相关信息具有重要价值。本研究旨在对卡特兰（Cattleya intermedia）的种子进行解剖学与组织化学表征，探究不同温度与贮藏周期下可能出现的变化。本研究设置的处理条件包括：温度梯度为25（±2）℃（室温）、-20℃（冷冻柜（freezer））、-80℃（超低温冰箱（ultra freezer））以及-196℃（超低温保存（cryopreservation））；贮藏周期分别为2个月、4个月与6个月。解剖学与组织化学分析采用扫描电子显微镜（scanning electron microscopy）与光学显微镜（light microscopy）开展。所用染色剂包括甲苯胺蓝（toluidine blue, TBO）、考马斯亮蓝（Coomassie brilliant blue, CBB）、苏丹IV（Sudan IV）以及高碘酸-希夫试剂（periodic acid-Schiff, PAS）。研究观测到，种子中的脱水现象是贮藏过程中产生的主要损伤。此外还记录到种子内部结构出现退变等变化，其中以25（±2）℃室温条件下贮藏的种子最为明显，该条件会导致种子主要储备成分的含量降低。在-80℃（超低温冰箱）条件下贮藏2个月与4个月的种子，其组织与细胞保存效果良好，证实了该条件可用于该物种种子的高效保存。