Researchers from the Chinese Academy of Sciences have introduced a groundbreaking breeding method aimed at developing heat-resistant kelp cultivars to combat the effects of global warming. Published on November 19, 2025, in the Journal of Phycology, this study highlights the pressing need for new cultivars of kelp species, particularly Saccharina japonica and Undaria pinnatifida, as rising seawater temperatures threaten their cultivation.
Kelp is a vital economic resource globally, but its cultivation is increasingly at risk due to climate change. This research, led by Prof. Shan Tifeng from the Institute of Oceanology, seeks to address this challenge through a novel triploid breeding method. While triploid breeding is common in terrestrial agriculture, its application in seaweeds has been limited.
Traditionally, obtaining diploid gametophytes from heterozygous sporophytes using apospory has resulted in variable and unpredictable sex ratios, complicating the breeding process. According to Prof. Shan, “This issue has become the primary technical bottleneck limiting triploid breeding in kelp.”
To overcome this hurdle, the research team built on doubled haploid (DH) population construction technology, focusing on Undaria pinnatifida. They devised a method to generate homozygous diploid gametophytes by inducing apospory in DH sporophytes. By crossing these homozygous diploid gametophytes with haploid gametophytes, the researchers successfully produced triploid sporophytes.
In their experiments, the researchers first derived DH sporophytes through the selfing of a monoicous gametophyte. Subsequently, they generated single-sex male diploid gametophytes via apospory. These male gametophytes were then crossed with three female haploid gametophyte clonal lines, resulting in the successful creation of three triploid hybrid lines.
The cultivation trials conducted at a seaweed farm demonstrated that the triploid hybrids outperformed conventional diploid cultivars. The new hybrids exhibited a faster growth rate, longer blades, enhanced resistance to high temperatures and aging, and a notable sterility characteristic.
“This triploid breeding method may also be applicable to other kelp species, as they share a similar life cycle,” Prof. Shan remarked. The findings provide a practical polyploid breeding tool for kelp, which could help develop more robust and adaptable cultivars, crucial for the sustained growth of the seaweed farming industry.
The study represents a significant advancement in kelp breeding, responding to the urgent call for cultivars that can thrive in warmer seas. With the potential to enhance the resilience of kelp farming, this research contributes to the broader conversation about adapting agricultural practices to the challenges posed by climate change.
For further details, the full study is available in the Journal of Phycology.
