Phenotypic diversity, growth and sexual differentiation in the progeny of wild <i>Kappaphycus alvarezii</i> (Gigartinales, Florideophyceae)

Abstract

Wild and fertile Kappaphycus alvarezii, both cystocarpic gametophytes and tetrasporophytes, were collected for in vitro spore release and cultivation. Six parental individuals with distinct phenotypes, i.e. variable colour and morphology, were selected. Growth rates of the corresponding diploid tetrasporophyte and haploid gametophyte progeny did not vary significantly. The mature tetrasporophytes growing from carpospores exhibited mostly green, brown and bicolour (green and brown) individuals – colours inherited from their parents. Conversely, the resulting gametophytes growing from tetraspores produced multicoloured individuals, or individuals with yellow, green, brown, grey, black, orange and red colouration. Sexual ambiguity was resolved on the eighth month with more females than males. Plants arising from single basal discs were observed to exhibit distinct colours in different branches and monoecious individuals with male and female reproductive structures were observed in different branches. Our study showed that wild populations and their progenies are a good source of new strains for future farming.