Thallus sectioning as an efficient monospore release method in Pyropia yezoensis (Bangiales, Rhodophyta)
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23RD INTERNATIONAL SEAWEED SYMPOSIUM, JEJU
Thallus sectioning as an efficient monospore release method in Pyropia yezoensis (Bangiales, Rhodophyta) Nianci Chen 1,2 & Lei Tang 1,2 & Xiaowei Guan 1,2 & Rui Chen 1,2 & Min Cao 1,2 & Yunxiang Mao 1,2,3 & Dongmei Wang 1,2 Received: 24 July 2019 / Revised and accepted: 7 November 2019 # The Author(s) 2019
Abstract The red seaweed Pyropia yezoensis is a marine crop of important economic value and is widely cultivated in the coastal areas of northern China. The current seedling-raising system relies on the germination of conchospores, a process not fast enough to meet the increasing demand from farmers. In this study, we developed a monospore-dependent seedling method based on the asexual reproduction of the Pyropia thallus. The Pyropia thallus was physically sectioned into small pieces (microthalli) that were cultivated at 15 °C. The algal cells in the microthalli became morphologically condensed, underwent cell division, and then developed into monospores on the 5th day. The monospores were able to attach to the seeding rope in 24 h and germinated into healthy thalli. To optimize the efficiency of monospore release, we tested the effect of temperature and the size and original positions of the microthalli as well as the age of the mother thallus. Microthalli with a size of 30–50 cells from the middle and apex of 21-day-old thalli cultivated at 15 °C yielded the optimum production of monospores. Theoretically, in this thallus-tothallus seeding strategy, 0.1 g of thallus could produce at least 107 monospores, with the same number of offspring thallus seedlings. Taking all of these advantages together, including the high efficiency, short time, low cost and easy operation, this physical sectioning method could serve as a promising seed source especially for new cultivars with superior traits in Pyropia farming and rapid replenishment of seedlings when thalli undergo disastrous diseases. Keywords Pyropia yezoensis . Monospores . Sectioning . Asexual reproduction
Introduction Pyropia yezoensis (previously Porphyra yezoensis) belongs to the red algal order Bangiales. It is one of the most economically important marine crops (Cao et al. 2016) in Far East countries including South Korea, Japan, and China. The annual production of Pyropia (both P. yezoensis and P. haitanensis) has Nianci Chen and Lei Tang contributed equally to this work. * Yunxiang Mao [email protected] * Dongmei Wang [email protected] 1
Key Laboratory of Marine Genetics and Breeding (OUC), Ministry of Education, Qingdao, People’s Republic of China
2
College of Marine Life Sciences, Ocean University of China, Qingdao, People’s Republic of China
3
Key Laboratory of Utilization and Conservation for Tropical Marine Bioresources (Hainan Tropical Ocean University), Ministry of Education, Sanya, People’s Republic of China
reached approximately 1.8 million tonnes, with an estimated value of approximately US$ 1.5 billion (http://www.fao.org/ fishery 2017). Pyropia yezoensis has been widely cultivated in densely
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