Effects of Temperature and Irradiance on Growth and Infection of Three Endophytic Green Algae

The three endophytes, Blastophysa rhizopus, Bolbocoleon piliferum, Ulvella leptochaete, were isolated in a laboratory culture from a Grateloupia lanceolata thallus collected in Jeju. Effects of temperature and irradiance on growth and infection of the three species, were examined. Based on the unialgal cultures, their growth was examined under six temperatures (9, 13, 17, 21, 25, $29^{\circ}C$) and two irradiance levels (60, $100{\mu}mol\;m^{-2}s^{-1}$). Also, infection experiments to the five hosts (Ulva intestinalis, Scytosiphon lomentaria, Gracilaria verimiculophylla, Chondrus ocellatus, and Grateloupia elliptica) with three endophytes were carried out under four temperatures (10, 15, 20, $25^{\circ}C$) and two irradiance levels (60, $100{\mu}mol\;m^{-2}s^{-1}$). In culture of the endophytes, optimum growth was found in $100{\mu}mol\;m^{-2}s^{-1}$ in combination with $21^{\circ}C$. At the end of infection experiment, endophytes were observed at all the hosts. Among three endophytes, U. leptochaete was the most common at the five hosts. However, we did not observe any endophytes at all hosts tested under $10^{\circ}C$ condition. Based on this result, it appears that temperature acts as a limiting factor to infection of the three species.

내생녹조 3종의 생장과 감염에 미치는 온도 및 광의 영향