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The ULPGC improves microalgae strains through controlled sexual reproduction

Within NewTechAqua, the Spanish Bank of Algae (Banco Español de Algas – BEA) FPCT – ULPGC (Spain) is involved in the working package 3 GENETICS, and more specifically in the subtask 3.1 Microalgae breeding programme.

The main objective of BEA is the improvement of microalgae strains for potential application in the European aquaculture sector. The approach to obtain such improvement in microalgae is novel, since it is based on pedigree selection, and implies genetic recombination through controlled sexual reproduction (i.e., classical breeding), thus bypassing the controversial issue of genetically modified organisms (GMOs).

An imperative prerequisite to carry out this research is to work with microalgae capable of undergoing sexual reproduction. Therefore, heterothallic diatoms were chosen for this purpose, and more than 30 wild-type strains belonging to eight putative species were screened for sexual activity in pairs.

The biggest achievement of the BEA Laboratory in the framework of the NTA project was the successful induction of sexual reproduction using selected pairs of Seminavis robusta strains (Figure 1).

 

Figure 1. Micrographs of sexual reproduction stages in Seminavis robusta (strains: P34 X P36) taken at the BEA Laboratory using an inverted microscope (objective lens: 40X): (a) gametogenesis and formation of a specialized zygote (auxospore); (b) and (c) bilateral expansion of two sibling cells in the auxospore; (d) two mature sibling cells. Scale bar = 10 µm.

Single-cell isolation of sexual descendants of S. robusta allowed the establishment of several F1 monoclonal cultures (i.e., progeny or offspring).

It remains to be determined whether the F1 offspring might have improved biotechnological traits compared to their wild-type parents, and to what extent. Therefore, the current work at the BEA is focusing on scaling up parent and progeny strains of S. robusta for biomass harvesting and biochemical characterization.

 

The work performed by the BEA in the framework of the NTA project led to the outcome of a Masters’ thesis and the participation to three international conferences in 2021, with scientific posters and oral presentations, i.e. “Young Algaeneers Symposium, 2021”, “10th Algal Biomass, Biofuel and Bioproducts Conference” and “Lipids in the Ocean Conference, 2nd Edition”.

The findings on S. robusta might pave the way to the implementation of classical breeding as a strategy for strain improvement, and hopefully open unprecedented perspectives for other microalgae species as well. The overall work on this challenging topic will ultimately contribute to achieving a more sustainable, resilient, and cost-effective European aquaculture!

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