Breeding in the Economically Important Brown Alga Undaria pinnatifida: A Concise Review and Future Prospects
Tifeng Shan* and Shaojun Pang*
First Pubulished: 2021-12-03
Undaria pinnatifida is the commercially second most important brown alga in the world. Its global annual yield has been more than two million tonnes since 2012. It is extensively cultivated in East Asia, mainly consumed as food but also used as feed for aquacultural animals and raw materials for extraction of chemicals applicable in pharmaceutics and cosmetics. Cultivar breeding, which is conducted on the basis of characteristics of the life history, plays a pivotal role in seaweed farming industry. The common basic life history shared by kelps determines that their cultivar breeding strategies are similar. Cultivar breeding and cultivation methods of U. pinnatifida have usually been learned or directly transferred from those of Saccharina japonica. However, recent studies have revealed certain peculiarity in the life history of U. pinnatifida. In this article, we review the studies relevant to cultivar breeding in this alga, including the peculiar component of the life history, and the genetics, transcriptomics and genomics tools available, as well as the main cultivar breeding methods. Then we discuss the prospects of cultivar breeding based on our understanding of this kelp and what we can learn from the model brown alga and land crops.
Characterization of the novel hybrid cultivar E25 of Saccharina japonica in the northern farming region of China
Li Su, Ti Feng Shan, Jing Li, Su Qin Gao, Shao Jun Pang#, Xiao Fei Leng, Yan Zhang, Ming Fu Zhang & Hong Tao Gao
First Pubulished: 2021-09-14
Use of cultivars with certain agronomical traits has been throughout the development history of kelp Saccharina japonica farming in China. Pursuit of high yield had been on top of all the parameters. However, in recent years, demand for better blade quality has steadily become intensive, especially in the northern farming region of this country. In this article, we report a newly bred, intraspecific hybrid E25 (as designation code), of its biological features and its applicability as a potential cultivar in the related farming region. A fully grown sporophyte of E25 could reach 4–5 m in length, 0.6–0.8 m in width, and 3–5 kg in fresh biomass depending on the farming zones and growing density within ca. 7-month cultivation period from November to May–June of next year. Unlike most of the cultivars or naturally grown sporophytes, sporophyte of E25 lacks fascia in the middle of the strip and possesses smooth blades. It has thicker ruffled undulate margins on both longitudinal sides and relatively low water content in its blade. Due to its much higher chlorophyll a content, blanched product is greener than most of the other cultivars, much favored by the processing industry. Seedling production of E25 relays on a pair of vegetatively propagated unialgal male and female gametophytes. High polymorphic microsatellite markers could accurately identify its uniformed genotype and distinguish it from other conventional cultivars. The first filial sporophytic generation of E25 (E25-F1) maintains the same yield level as its parent, reaching 23–25 kg m−1 cultivation rope, but with larger deviations in individual sizes as reflected by its higher coefficient of variations (CV).
First Genome of the Brown Alga Undaria pinnatifida: Chromosome-Level Assembly Using PacBio and Hi-C Technologie
Shan T, Yuan J, Su L, Li J, Leng X, Zhang Y, Gao H and Pang S#
First Pubulished: 2020-12-28
The brown alga Undaria pinnatifida (Harvey) Suringar is an economically important kelp species native to the Northwest Pacific and has been extensively farmed as human food in East Asia for more than half a century (Yamanaka and Akiyama, 1993). It is also an important resource for extracting biologically active compounds such as fucoidans which have diverse applications in pharmaceutical and cosmetic industries (Zhao et al., 2018; Yoo et al., 2019). Its annual yield worldwide has been more than two million tons since 2012 ( Nowadays U. pinnatifida has become a cosmopolitan species due to its worldwide spread in recent decades, attracting increasing public attention (South et al., 2017). It has been listed as one of the world's 100 worst invasive species (Lowe et al., 2000), and in Europe has been regarded as one of the top 10 worst invasive species (Gallardo, 2014).
Aquaculture of the hybrid cultivars of Saccharina japonica: Removing the obstacle of sori production by photoperiodic control
Su L, Shan TF, Li J, Pang SJ, Leng XF, Zhang Y, Gao HT.
First Pubulished: 2020-11-12
In aquaculture of the kelp Saccharina japonica, hybrid cultivars could improve both the yield and quality of the farmed products. Hybrid cultivars refer to the diploid macroscopic offspring resulted from crossing a pair of haploid vegetative gametophyte cell lines. When these two cell lines are derived from individuals that are geographically isolated, the adult sporophytic offspring mostly remain immature in their second year of growth from June to September in the sea. The absence of sori in the adult sporophytes of the hybrid during this period prevents them from being used as parental ones for releasing spores to produce “summer seedlings” in hatchery. This is due to the seasonal restriction of hatchery operation which requires the availability of matured sori exclusively in August in the temperate zone in the northern hemisphere. The reasons for appearance of nonsporulating adult individuals has never been investigated although raising adult sporophyte in land-based tank filled with recirculated cold water at 10 °C has been a routine operation in hatchery enterprises in the subtropical zone in the south region of China for more than 20 years. While in the north region of China, parental sporophytes have been always raised in the sea until they are used for hatchery. From 2017 to 2019, we have conducted a series of culture experiments, both in beakers with isolated thallus in incubators and in large concrete tanks with intact individuals, trying to understand this phenomenon and look for a solution. The results showed that, (1) the hybrid cultivars demonstrated a feature of photoperiodic short-day plant and that it could form sorus within 25 days when exposed to SD at higher temperature (18 °C); (2) the hybrid cultivar maintains unique genetic structures different from the conventional ones as revealed by use of ten polymorphic microsatellite markers; (3) the sensitivity of the hybrids to the shortening of day-length differs in at least 10 days among individuals and could be inherited to its offspring; (4) sori induction in the intact adult sporophytes could be achieved within a month when supplied with SD, applicable to all current cultivars including the hybrids. The discovery and solution presented in this article has opened a gateway to utilization of hybrid cultivars in the giant kelp farming industry in China.
Construction of a high-density genetic map and mapping of a sex-linked locus for the brown alga Undaria pinnatifida (Phaeophyceae) based on large scale marker development by specific length amplified ...
Shan T, Pang S#, Li J, Li X, Su L.
First Pubulished: 2015-11-05
Undaria pinnatifida is an important economic brown alga in East Asian countries. However, its genetic and genomic information is very scarce, which hinders further research in this species. A high-density genetic map is a basic tool for fundamental and applied research such as discovery of functional genes and mapping of quantitative trait loci (QTL). In this study the recently developed specific length amplified fragment sequencing (SLAF-seq) technology was employed to construct a high-density genetic linkage map and locate a sex determining locus for U. pinnatifida.