Em. Plastino et al., Codominant inheritance of polymorphic color variants of Gracilaria domingensis (Gracilariales, Rhodophyta), GENET MOL B, 22(1), 1999, pp. 105-108
Agar is the most valuable phycocoloid in the world market. Currently, about
half of its production is obtained from the red alga Gracilaria (Gracilari
ales, Rhodophyta). Consequently, this genus has been the subject of many st
udies worldwide. A common green color variant of G. domingensis (Kutzing) S
onder ex Dickie was found in a natural population on the northeastern coast
of Brazil. Crosses were performed to determine the mode of color inheritan
ce. The results can be interpreted as the expression of a pair of codominan
t alleles, where the green and red phenotypes are homozygous, and the heter
ozygotes present a brownish color. Heterozygous tetrasporophytes, at least
until they are 4-5 cm long, exhibit a parental influence on the female game
tophyte, since the reddish-brown or greenish-brown color is dependent on th
e female parent color (red or green). Mixed reproductive phases, as well as
specimens with patches of different colors bearing spermatangia or cystoca
rps, were observed in laboratory cultures. Gametophytes that resulted from
in situ germination of meiospores were also observed, and could be easily d
etected when red or green gametophytes were grown on brown tetrasporophytes
.