Assessment of genetic and phenotypic diversity of the giant kelp, Macrocystis pyrifera, to support breeding programs

Abstract

The accelerated development of seaweed aquaculture is stimulating research on the genetic drivers of phenotypic diversity of the target species, in order to optimize breeding strategies, to help determine the choice of source populations, and for the selection of traits and varieties that fit with the environmental variability of the production site. This study investigates the spatial variation of the genetic and phenotypic diversities in natural populations of the giant kelp Macrocystis pyrifera, and evaluates the potential for modifying agronomic traits through controlled breeding. Nine microsatellites and 12 morphological traits were used to describe the distribution of diversity present along the Southeastern Pacific (SEP) Coast. We expected concordant patterns of spatial discontinuities if the genetic background was driving morphological divergence across habitats. Crossing experiments were made to assess the heritability of specific traits and evaluate the performance of the F1 generation in the laboratory and in open sea cultivation respectively. Our results revealed four genetic clusters along the latitudinal distribution of M. pyrifera populations, tightly correlated with the existence of major environmental discontinuities. These clusters also matched clusters of morphological diversity, suggesting that both morphological and genetic diversities responded to the same environmental drivers. In crossing experiments, no significant differences were detected between selfed and outbred F1, in morphology, growth and chemical components, but a high variability among all different crosses was observed, revealing a high degree of heritable phenotypic variance. Although, the results suggest that the morphological variation of Macrocystis along the SEP coast is strongly driven by the genetic background. Our controlled crosses 3 were also indicative of a high potential for using this genetic variability in breeding programs for sustainable aquaculture development.

Cultivar Development of Kelps for Commercial Cultivation—Past Lessons and Future Prospects

“…The genetic structuring appears to be affected both by spread via ocean currents (Mooney et al, 2018) and by environmental variation and local adaptation (Nielsen et al, 2016). Similar studies of M. pyrifera populations along stretches of the American Pacific coast also identified several distinct genetic groups and suggested that both ocean currents and local adaptation to different environments can be important for this grouping (Alberto et al, 2011;Johansson et al, 2015;Camus et al, 2018).…”

“…Other peculiar modes of reproduction that can occur in Laminariales include apogamy, where a haploid sporophyte can emerge directly from a somatic cell of a gametophyte (Nakahara and Nakamura, 1973;Fang, 1984;Wu and Lin, 1987;Müller et al, 2019) (Figure 1C), and apospory, where a diploid gametophyte can develop from vegetative cells of a diploid sporophyte without any meiosis or spore formation (Nakahara and Nakamura, 1973;Lewis et al, 1993) (Figure 1D). Self-fertilization appears to be possible in most studied species of Laminariales (Wu and Lin, 1987;Brawley and Johnson, 1992;Kraan et al, 2000;Camus et al, 2018). Some kelp species are annual or biennial, but most are perennial (Schiel and Foster, 2006).…”

Macroalgal germplasm banking for conservation, food security, and industry

“…Despite a fast-growing interest in commercial aquaculture, corresponding with a rapidly increasing global demand for nutrition supplementation and industry raw material, few researchers outside of Asia have explored sustainable domestication programs, including the creation of macroalgae germplasm banks [31,39,75,76]. Several facilities, such as the National Institute of Fisheries Science-Seaweed Research Center in South Korea and the Ocean University of China and Chinese Academy of Science, have dedicated infrastructure and research to the maintenance of commercially important macroalgal species and cultivars.…”

Intraorganismal genetic heterogeneity as a source of genetic variation in modular macroalgae

“…, Camus et al. ) as well as their historical phylogeographic diversification (e.g., Tellier et al. , Buonomo et al.…”

“…In macroalgae, most genetic studies are focused on the population and regional levels and have mainly dealt with resolving the taxonomy of seaweeds and their phylogenetic relationships (e.g., Ragan et al 1994, De Clerck et al 2005, Gonz alez et al 2012, Leliaert et al 2012, Verbruggen et al 2016, Steen et al 2017. Moreover, researchers have studied the population genetics of seaweeds with a focus on genetic variability and its distribution within and among populations (e.g., Valero et al 2001, Mart ınez et al 2003, Guillemin et al 2008, Wang et al 2008, Andreakis et al 2009, Alberto et al 2010, Krueger-Hadfield et al 2011, Camus et al 2018) as well as their historical phylogeographic diversification (e.g., Tellier et al 2009, Buonomo et al 2017, Neiva et al 2018). Few studies have assessed different levels of genetic diversity in macroalgae.…”