RESUMO
ABSTRACT 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 ℃ and 25 ℃. In contrast, in darkness at 20 ℃ from one to 30 days, spores did not germinate. However, when dark-cultured spores transferred to continuous light, they started to geminate in 48 hours. In addition, effects of 20 ℃ and 25 ℃ on sporeling were compared. In a continuous light condition, sporelings grew longer and developed more protonema branches in the 20 ℃ treatment than in the 25 ℃ 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℃). These observations suggest that spore germination and sporeling development is regulated by light and temperature.
RESUMO
The influence of light and nutrients on the different germination phases of Bryum argenteum spores was studied. The following treatments were used: distilled water and nutrient solution under light (12 h) and continuous darkness. The spores germinated when exposed to light, independent of both medium used. Under darkness, the spores swelled and became chlorophyllous. In the presence of nutrient solution, the germination occurred earlier (after two days) when compared to the distilled water (after more than three days). Nutrients were needed to complete the last germination phase in the majority of spores and to provide the protonemal growth.
Neste estudo procuramos avaliar a importância de fatores abióticos sobre a germinação de esporos e o desenvolvimento do protonema de musgos. Para isso, nós analisamos o efeito da disponibilidade de luz e nutrientes sobre diferentes fases da germinação de esporos de um musgo amplamente distribuído. Bryum argenteum geralmente apresenta muitos esporos por cápsula, e estes são amarelos devido à presença de muitos corpúsculos lipídicos. Foram usados os tratamentos: água destilada e solução nutritiva sob luz (12 h) e escuro contínuo. Os esporos mostraram-se fotoblásticos positivos, ou seja, apenas germinaram sob luz, independentemente do meio utilizado. Sob escuro os esporos apenas embeberam, tornando-se clorofilados provavelmente a partir da quebra de reservas. Em solução nutritiva a germinação ocorreu mais rapidamente (dois dias) em relação à água destilada (mais de três dias após cultivo). No entanto, os nutrientes foram necessários para completar a última fase da germinação da maioria dos esporos.