Xanthophyll cycle and Low temperature adaptation in Antarctic alge, C. neogracile

Abstract

Antarctic microalga, Chaetoceros neogracile was investigated to dissect the mechanism of survival in the low temperature condition. The growth of C. neogracile was compared in different culture conditions. C. neogracile was actively growing in 4oC culture condition and the growth rate of C. neogracile under continuous light was significantly higher than the growth rate under light- dark culture condition. The pool size of the xanthophyll cycle pigment diadinoxanthin (DD) and diatoxanthin (DT) in C. neogracile relyed on illumination conditions during culture. On exposure to high-light intensity, extensive de-epoxidation of DD to DT was observed in low temperature condition, which suggested that xanthophyll cycle plays a role in the prevention of photoinhibitory damage to the photosynthetic apparatus. C. neogracile which are normally grown in 4 oC were put under stress in 10 oC to observe the growth rate and the change in each pigments. The results were normalized using chlorophyll a and cell number. Further study will be carried out using segmented temperature ranges and high-light conditions.