Figure - available from: Botanica Marina
This content is subject to copyright. Terms and conditions apply.
Schematic representation of algal life cycles. Diploid and haploid stages are marked by white and black arrows, respectively. (A) Brown algal life cycle. Fucales are characterized by a diplontic life cycle. Meiosis in the reproductive tissue is immediately followed by gametogenesis and syngamy producing a diploid zygote. Most algae such as Dictyota, Scytosiphon and Laminaria exhibit a diplohaplontic life cycle where a haploid gametophyte alternates with a diploid sporophyte. Here following meiosis the resulting spore develops into a multicellular organism. Both haploid and diploid phases may be of identical morphology (isomorphic) (Dictyota), or the two phases may develop differently (heteromorphic) with either the gametophyte (Laminaria) or the sporophyte (Scytosiphon) being microscopic. Many unicellular algae (Chlamydomonas) are characterized by a haplontic life cycle where the formation of a zygote is immediately followed by a meiotic division. (B) Simplified diplohaplontic life cycle of Ectocarpus siliculosus. Meiosis (a) takes place in the sporophyte (diploid) to produce haploid spores. First cell division in germinating spores is asymmetric (b) and they grow into multicellular gametophytes. Gametophytes produce morphologically identical but physiologically differentiated male and female gametes (c), which fuse to form a zygote. After a symmetrical first cell division (d) the zygote grows into a diploid sporophyte. Alternatively, gametes that do not meet a partner of the opposite sex grow into diploid parthenosporophytes by means of parthenogenesis combined with endoreduplication (e) or into a haploid parthenosporophyte (f). The latter produces meiospores via a nonreductive apomeiotic event (g). (C) Life cycle of the red alga Chondrus showing three distinct stages: the gametophyte, the sporophyte and the carposporophyte, which develops parasitically on the gametophyte after fertilization. Loops connecting a generation with itself denote asexual reproduction mediated by vegetative reproduction (e.g. fragmentation, propagule formation) (Fucus, Dictyota), the formation of asexual spores (mitospores) (Dictyota, Ectocarpus, Laminaria), mitosis (Chlamydomonas) or parthenogenetic development of unfertilized (female) gametes (Scytosiphon, Laminaria, Ectocarpus). Figure adapted from Bogaert et al. (2013).
Source publication
Knowledge of life cycle progression and reproduction of seaweeds transcends pure academic interest. Successful and sustainable seaweed exploitation and domestication will indeed require excellent control of the factors controlling growth and reproduction. The relative dominance of the ploidy-phases and their respective morphologies, however, displa...
Citations
... Por lo anterior, es posible inferir que las algas marinas bentónicas que habitan el litoral de Veracruz pueden ser consideradas Reproducción En el presente estudio, de 48 especies documentadas de Phaeophyceae, 42 se encontraron en estado reproductivo, hecho que coincide con lo registrado por Mendoza-González et al. (2000), Mateo-Cid et al. (2000, 2013 y Ávila-Ortiz et al. (2011). Estudios experimentales y observaciones de campo sugieren que la luz y la temperatura, o la combinación de ambas, a menudo inducen la fertilidad en las algas marinas (Liu et al., 2017). ...
Antecedentes y Objetivos: Los primeros registros de algas marinas bentónicas para el litoral de Veracruz datan de 1846; después de 114 años, ficólogos mexicanos reiniciaron su estudio. Actualmente, se tienen registradas 312 especies. Considerando está riqueza específica, las modificaciones y actualizaciones taxonómicas en diversos grupos, el objetivo de este trabajo fue presentar una lista de las algas marinas del litoral veracruzano organizadas por categorías taxonómicas incluyendo datos de distribución, temporalidad y nuevos registros para el área de estudio. Métodos: Se realizaron 92 muestreos durante 18 años, en el nivel intermareal de 11 localidades del litoral, se obtuvieron registros previos desde 1960 a 2020 a través de una revisión bibliográfica y de la colección ficológica del herbario ENCB. El estatus nomenclatural de cada especie y el sistema de clasificación fueron revisados y actualizados. La diversidad α para cada localidad fue calculada con el índice de Shannon-Wiener; también se realizó un análisis de agrupamiento mediante UPGMA con el programa PAST v. 3. Resultados clave: El listado ficoflorístico incluye 316 taxones de algas marinas bentónicas distribuidas en 3 Phyla, 6 clases, 31 órdenes, 60 familias y 130 géneros. Cada especie incluye distribución en el litoral de Veracruz, reproducción, estacionalidad, hábitat, observaciones, bibliografía y número de catálogo del herbario ENCB. Los análisis de diversidad α muestran que la mayor diversidad está en las localidades con sustrato predominantemente rocoso con 180 especies. Las lluvias de verano registraron un elevado número de especies (269); Barra de Cazones alberga 181 especies, además, se encontraron 70 registros nuevos; así, el número de taxones aumentó a 391. Conclusiones: El listado revela una mayor riqueza específica de algas marinas comparada con la registrada en Yucatán, Campeche y Tabasco. La afinidad fitogeográfica de las algas del litoral de Veracruz es mixta, ya que ahí confluyen taxones tropicales y caribeños. Es necesario mantener un monitoreo constante para determinar cambios de la comunidad de algas para establecer programas de conservación y aprovechamiento.
... Mode of reproduction excludes vegetative propagation. Categories: predominantly sexual, >90 % of species; sexual and asexual, both modes in 10-100 % of species; no sexual cycles known, 0 % sex; estimates after Liu et al. (2017) for algae and Mogie (1992) for land plants. (A) Hypothetical degree of oxidative stress (blue thick arrows) accumulating over the phylogeny of plants, starting with oxygen respiration in the last common ancestor of eukaryotes (LECA), with additional stress via photosynthesis and a further increase with terrestrialization (de Vries and Archibald, 2018; for comparison with animals and fungi, see Hörandl and Hadacek, 2020). ...
... species, which might respond differently to these extreme climatic events depending on the species. In particular, the role of abrupt thermal stress in triggering fertility in interaction with i) other extrinsic factors (e.g., day length, light quality, nutrients), ii) and intrinsic factors (e.g., genetic control, endogenous signalling molecules; Liu et al., 2017) should be clarified. The timing of reproduction can be altered by MHWs, so it can be unpredictable even in areas where phenology is well known (Bevilacqua et al., 2019). ...
... All reproductive phases were found throughout the year, except for the months of November, January, and March when no male gametophytes were recorded. The presence of fertile plants at the same site was also reported in other eucheumatoid reproductive biology studies (Ganzon-Fortes 2016; Hinaloc 2017; Rodrigora 2017; Roleda et al. 2017). Considering that the spermatia in red algae lack flagella, it may present a challenge for the fertilization of an egg by nonmotile sperm. ...
... Whether there are associated environmental and genetic controls (Liu et al. 2017) on reproduction, ploidy distribution, and sex determination among eucheumatoids remains to be studied. The above information is vital in identifying wild populations that can provide a continuous supply of fertile plants for strain selection and crop improvement. ...
Kappaphycus species are globally cultivated in tropical waters as a major source of k-carrageenan. Since the early 1970s, Kappaphycus farming, through clonal propagation, has been confined to a few good-quality commercial strains of unknown ploidy and/or life history phase. After five decades of successful cultivation, the productivity of Kappaphycus spp. has continually declined. This has been attributed to low genetic variability, making the >50-year-old cultivars more susceptible to environmental stressors, pests, and diseases. Hence, the establishment of new cultivars with unique genetic makeup and corresponding desirable traits can provide alternative seedstocks from the currently cultivated strains. Cultivar development includes the collection of wild individuals, both vegetative and reproductive materials, for culture collection and biobanking, spore release and cultivation, selection, and breeding. Moreover, the distinction of specific life history phases, sex, and ploidy among the established cultivars can be tested for specific traits, such as vigor and fitness, productivity, and biochemistry. This initiative can avoid repeated crop failure associated with old and fatigued strains and conduct targeted farming of specific cultivars with corresponding known traits. Understanding their ecological tolerance to different abiotic factors can also mitigate risks in seaweed farming in relation to climate change. Continuous cultivar development is necessary for future crop domestication and improvement programs to sustain the livelihoods of thousands of small-scale farmers and the multi-million-dollar seaweed industry.
... The ecologically and economically important brown algae of the order Laminariales, are characterized by a heteromorphic haplodiplontic life cycle alternating between macroscopic diploid sporophytes and microscopic haploid stages (meiospores, gametophytes;Lüning, 1991;Liu et al., 2017). They are all dioicous with rare observations of monoicous characteristics (e.g. ...
... The complex life cycles of algae make understanding and controlling life cycles particularly challenging, which has repercussions for domesticating new species for aquaculture. The life cycle of algae depends not only on its genotype but also on environmental factors (Liu et al., 2017). From a molecular perspective, mechanisms involved in life cycle transitions are to a certain level conserved among algae (Goodenough et al., 2007;Lopez et al., 2015). ...
... Hence, there is ever-increasing pressure to develop new and productive culture technologies and to domesticate new species with different product applications. Toward this end, a detailed understanding of seaweed life cycles may enable the control of life-history stages, which is a prerequisite for any form of aquaculture to become sustainable (Liu et al., 2017). ...
The sub‐tropical red seaweed Asparagopsis taxiformis is of significant interest due to its ability to store halogenated compounds, including bromoform, which can mitigate methane production in ruminants. Significant scale‐up of aquaculture production of this seaweed is required; however, relatively little is known about the molecular mechanisms that control fundamental physiological processes, including the regulatory factors that determine sexual dimorphism in gametophytes. In this study, we used comparative RNA‐sequencing analysis between different morphological parts of mature male and female A. taxiformis (lineage 6) gametophytes that resulted in greater number of sex‐biased gene expression in tips (containing the reproductive structures for both sexes), compared with the somatic main axis and rhizomes. Further comparative RNA‐seq against immature tips was used to identify 62 reproductive sex‐biased genes (59 male‐biased, 3 female‐biased). Of the reproductive male‐biased genes, 46% had an unknown function, while others were predicted to be regulatory factors and enzymes involved in signaling. We found that bromoform content obtained from female samples (8.5 ± 1.0 mg·g ⁻¹ dry weight) was ~10% higher on average than that of male samples (6.5 ± 1.0 mg·g ⁻¹ dry weight), although no significant difference was observed ( p > 0.05). There was also no significant difference in the marine bromoform biosynthesis locus gene expression. In summary, our comparative RNA‐sequencing analysis provides a first insight into the potential molecular factors relevant to gametogenesis and sexual differentiation in A. taxiformis , with potential benefits for identification of sex‐specific markers.
... For example, Chlamydomonas has a simple life cycle, in which cells divide and grow under favorable conditions, and produce spores or zoospores when conditions become unfavorable. Seaweed, on the other hand, have more complex life cycles, in which they produce spores or spores that develop into new individuals, or they can undergo sexual reproduction, producing gametes that fuse to form a new individual (Liu et al. 2017). ...
Many species of microalgae have the capability to uptake the nutrients from the wastewater even in the presence of nitrogen, phosphorus, inorganic and organic toxins and pathogens. Algae grow in light or dark environments and also by the uptake of carbon dioxide or any other inorganic and organic carbon source. The bacteria already present in the wastewater breaks the complex organic matter, while algae consume them and provide the oxygen necessary to treat the water by compensating the Biological Oxygen Demand. Algal photo bioreactors are a promising technology in treating the wastewater and also carbon sequestration. There are various configurations of algal photobioreactors namely: vertical plastic bag, tubular, column, panel, and membrane photo bioreactor. This book chapter explains these configurations and also the parameters such as nutrient concentration, mixing and agitation, pH, light, and temperature that influence the growth of algae in the photo bioreactor. It also explains the need for different components in the photo bioreactor to vary or control the process parameters and also provides solutions for the challenges involved during use of photo bioreactor for wastewater treatment.
... For seaweed cultivation to reach its socio-economic and market potential, yields need to be increased, for which research and innovation in selective breeding (Charrier et al. 2015;Liu et al. 2017) and biorefinery processes (Patyshakuliyeva et al. 2019;Torres et al. 2019) are urgently needed Bak et al. 2018). In 2020, 36.17 million tonnes of algae were produced globally, of which 97% was cultivated seaweed (FAO 2022). ...
The feasibility, benefits, risks, and consequences of using sporeless sporophytes to aid the upscaling of kelp cultivation in Europe and North America, as well as the barriers that currently exist and how these may be overcome, are reviewed here. Taking environmental, industrial, and regulatory factors into account, we will discuss the use of domesticated sporeless sporophytes as an asset to facilitate upscaling kelp cultivation without potentially impacting wild genetic diversity.
... Understanding the reproductive phenology of seaweeds is also fundamental for the development of sustainable seaweed aquaculture (Searles 1980, Charrier et al. 2017, de Bettignies et al. 2018. Such knowledge can form the basis for developing multiple components of seaweed aquaculture, such as knowing when to conduct outplanting and harvesting, identifying peaks and patterns in reproduction to enable targeted wild-collections of broodstock, and determining the optimal culture conditions for seaweed maturation and reproduction to develop hatchery and nursery cultivation technologies (Charrier et al. 2017, Fernand et al. 2017, Liu et al. 2017, Kim et al. 2019, Leal et al. 2021. Identifying how the seasonal timing of reproductive events varies with prevailing environmental conditions also enables the design of management strategies for climate resilient aquaculture (Charrier et al. 2017). ...
