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Intrinsic and extrinsic control of reproduction in the green tide-forming alga, Ulva rigida

Lookup NU author(s): Guang Gao, Professor Tony Clare, Dr Craig Rose, Dr Gary Caldwell



This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND).


The green seaweed Ulva is the causative genus behind nuisance green tides, but also has uses in the food and feed industries. Growing interest in Ulva cultivation has highlighted knowledge gaps in the mechanisms that regulate maturation and reproduction, particularly interacting intrinsic and extrinsic factors. In this study, the effects of temperature shock, dehydration, culture temperature, nitrate concentration, and thallus fragmentation were investigated on blade and basal tissue from U. rigida thalli of varying ages. A 20-minute temperature shock induced a mean reproductive response of 94.7% in blade tissue by day five. The reproductive rate of blade tissues increased with the degree of fragmentation and with growth media renewal. Combining temperature shock with fragmentation triggered 97.3% of blade tissues to reproduce by day three. In contrast, dehydration reduced reproduction. A temperature of 18°C in combination with a nitrate concentration of 100 µmol L-1 halved the maturation period (28.4 days) compared to cultivation under lower temperature and nitrate conditions (62.1 days). Reproduction in blade tissues increased with plant age but basal tissues remained in the vegetative state even after temperature shock and fragmentation. Furthermore, the presence of basal tissues suppressed reproduction of blade tissues. These findings indicate that extrinsic factors such as temperature shock and fragmentation induce reproduction in blade but not basal tissues, which appears to be under the control of intrinsic factors such as sporulation inhibitors. The differentiation of Ulva cells could support the rapid growth of Ulva when environmental conditions are favourable and also facilitate survival under unfavourable conditions.

Publication metadata

Author(s): Gao G, Clare AS, Rose C, Caldwell GS

Publication type: Article

Publication status: Published

Journal: Environmental and Experimental Botany

Year: 2017

Volume: 139

Pages: 14–22

Print publication date: 01/07/2017

Online publication date: 28/03/2017

Acceptance date: 26/03/2017

Date deposited: 27/03/2017

ISSN (print): 0098-8472

ISSN (electronic): 1873-7307

Publisher: Elsevier


DOI: 10.1016/j.envexpbot.2017.03.016


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