Carpospore early development and callus-like tissue induction of Chrysymenia wrightii (Rhodymeniaceae, Rhodophyta) under laboratory conditions

Abstract

Morphological and culture studies of germlings derived from carpospores of Chrysymenia wrightii (Harvey) Yamada were carried out under various treatments combining temperature and irradiance. Basal, main, and tip branches were applied for inducing callus-like tissue. Focus was on how carpospores develop into germlings, how callus-like tissues are induced from explants, and how temperature and irradiance affect carpospore germination and discoid crust growth. Results show that carpospore development can be divided into three stages: division stage, discoid crust stage, and erect juvenile germling stage. Discoid crusts, even more than ten, might coalesce into a big discoid crust, and then developed into germlings. Filamentous fronds, formed on the rims of discoid crusts, exhibited in self-existence or co-existence form with germlings, could form spherical tufts if cultured separately. Filamentous callus-like tissues appeared on the tip branches after 13 days. PES is suitable for filament induction and culture, and filaments have potential use in germplasm preservation and vegetative propagation. Temperature (10, 15, 20, 25°C) and irradiance (8 and 36 µmol photons m−2 s−1) significantly influenced carpospore germination rate and discoid crust diameter. Carpospores germinated normally under 36 µmol photons m−2 s−1, 15~25°C, and maximum growth of discoid crusts was at 25°C, 36 µmol photons m−2 s−1; 10°C and 8 µmol photons m−2 s−1 did not favor carpospore germination or discoid crust growth.