Reproductive strategies of Lessonia berteroana (Laminariales, Phaeophyceae) gametophytes from Chile: Apogamy, parthenogenesis and cross-fertility with L. spicata

Abstract

Lessonia berteroana is one of the most exploited seaweeds in the Southeastern Pacific and its populations are recurrently facing overexploitation in northern Chile. Since germplasms are not available, we decided to start gametophyte biobanking to support conservation measures for this important resource in the future. Spores of L. berteroana from nine localities at the Atacama coast were used to establish clonal male and female gametophyte cultures. Unexpectedly, after isolation and under low light conditions, juvenile sporophytes originated from somatic cells via apogamy in most female gametophyte strains. In addition, eggs from solitary female gametophytes from Caleta Cisnes and Torres del Inca had a strong tendency to generate sporophytes by parthenogenesis, some of them even under low light regimes. Contrarily, female gametophytes of the sister species Lessonia spicata from southern Chile showed no evidence for apomixis. When one of these L. berteroana strains is cross-fertilized with L. spicata, true hybrids emerged based on the presence of eggs and subsequent sperm attraction. These observations contrast with (i) kelp recruitment assumed to be majorly by sexual reproduction and (ii) the strict reproductive separation of the two taxa reported for natural populations within their contact zone at 30°S and highlight their consideration for future repopulation and breeding programs of Lessonia.