A reasonable strategy for Caulerpa lentillifera J. Agardh (Bryopsidales, Chlorophyta) transportation based on the biochemical and photophysiological responses to dehydration stress

Abstract

Caulerpa lentillifera is an economically important macroalgae. Many parental algae are needed in the commercial cultivation of C. lentillifera, and these algae are normally transported under dehydration. This study aimed to clarify the biochemical and photophysiological responses to dehydration stress to provide a theoretical basis for C. lentillifera transportation. The various biochemical and photophysiological changes to C. lentillifera were characterized during various lengths of dehydration stress. The relative water loss varied between 1.4% and 4.9% during dehydration periods of 2–120 h. Compared to the control, the contents of malondialdehyde, superoxide anion, and hydrogen peroxide during dehydration for 6–120 h increased significantly. Moreover, the chlorophyll fluorescence parameters (maximal photochemical efficiency of photosystem II, saturated photosynthetically active radiation, relative electron transport rate, and initial slope of rapid light curve) and the contents of chlorophyll a and soluble protein all decreased with increasing dehydration duration. These results suggest that dehydration could lead to oxidative stress in C. lentillifera. Compared to the control, the content of soluble polysaccharide and the activities of antioxidant enzymes (peroxidase, superoxide dismutase, and catalase) were both substantially enhanced at a certain stage of dehydration, and the proline content was relatively higher during all dehydration periods, indicating that these compounds probably play a crucial role in defensive reactions against dehydration-induced oxidative stress in C. lentillifera. After recovery for 72 h, the vegetative reproductive capability of C. lentillifera with a dehydration duration of 2–24 h was not significantly different from that of the control. Based on the above results, a reasonable strategy of maintaining dehydration within 24 h was proposed for C. lentillifera transportation. Moreover, photoinhibition easily occurs in C. lentillifera following rehydration after prolonged transportation, indicating that strong light stimulation should be avoided during the early recovery stage.