Full Length Research Paper

Laboratory studies on vegetative regeneration of the gametophyte of Bryopsis hypnoides Lamouroux (Chlorophyta, Bryopsidales)

Naihao Ye¹*, Hongxia Wang², Zhengquan Gao³ and Guangce Wang²

¹Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao 266071, China.

²Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China.

³School of Life Sciences, Shandong University of Technology, Zibo 255049, China.

*Corresponding author. E-mail: yenh@ysfri.ac.cn. Tel: 0086 0532 85830360.

Abbreviations: LD, Light/dark; FFB, free floating branch; MA, macrothallus.

Accepted 14 January, 2010

   Abstract

Vegetative propagation from thallus segments and protoplasts of the gametophyte of Bryopsis hypnoides Lamouroux (Chlorophyta, Bryopsidales) was studied in laboratory cultures. Thallus segments were cultured at 20°C, 20 μmol photons m^-2 s^-1, 12:12 h LD); protoplasts were cultured under various conditions, viz. 15°C, 15 μmol photons m^-2 s^-1, 10:14 h LD; 20°C, 20 μmol photons m^-2 s^-1, 12:12 h LD; and 25°C, 25 μmol photons m^-2 s^-1, 14:10 h LD. Microscope observation revealed that the protoplast used for regeneration was only part of the protoplasm and the regeneration process was complete in 12 h. The survival rate of the segments was 100% and the survival rate of protoplasts was around 15%, regardless of culture conditions. Protoplasts were very stable in culture and were tolerant of unfavorable conditions. Cysts developed at the distal end or middle portion of gametophytic filaments under low illumination (2 - 5 μmol photons m^-2 s^-1), the key induction factor. Cysts formed several protoplast aggregations inside or the cyst as a whole detached directly from the matrix and all the units were able to develop directly into new gametophytes. Regeneration directly from protoplasts and thallus segments were also discovered in the field. A relatively completed life history of B. hypnoides is established with newly discovered propagation methods, namely protoplast regeneration.

Key words: Bryopsis hypnoides, protoplast, thallus segment, propagation method, life history.