Spore Germination and Protonemal Development of Dolichomitriopsis diversiformis

Dolichomitriopsis diversiformis is an endemic and threatened moss in eastern Asia. In vitro culture and light microscopic observation were employed to study its developmental process from spore germination to the formation of young gametophyte, as well as effects of light and temperature on its spore germination and protonemal development. Microscopic observations revealed that its spores were positively photoblastic with exosporous germination, and sporelings were classified as the bryum-type. Light and dark conditions were compared to understand their effects on spore germination. In 24 h continuous illumination, all spores germinated in both 20 °C and 25 °C. In contrast, in darkness at 20 °C from one to 30 days, spores did not germinate. However, when darkcultured spores transferred to continuous light, they started to geminate in 48 hours. In addition, effects of 20 °C and 25 °C on sporeling were compared. In a continuous light condition, sporelings grew longer and developed more protonema branches in the 20 °C treatment than in the 25 °C treatment. It was interesting that a phenomenon of slow and hysteretic spore germination and protonematal development was observed in natural light and room temperature (5-10°C). These observations suggest that spore germination and sporeling development is regulated by light and temperature.