ISSR analysis on the heterosis in hybrids of Porphyra haitanensis

The wild strain (♀) of Porphyrahaitanensis was crossbred with the red strain (♂) one which selected through induction of mutation to get the hybrid conchocelies and thallus.Of all the hybrids, 5 healthy thallus which have predominance of growth and other economic characteristics were selected to digest with snail enzymes, and through somacloning and conchocelies culturing, 5 s rains (A、B、C、D、E) which have steady characters were obtained.And then, ISSR method was used to study the heterosis of the P.haitanensis parents and these 5 hybrid strains, 21 ISSR primers(were screened from 67 primers) gave rise to 366 discernible DNA bands of which 347 (94.8%) were polymorphic, the size of ISSR markers were highly reproducible ranged from 400 to 4000 bp.By statistic and analyzing these amplified bands, it can find that the average genetic similarity between the 5 hybrids and female parent and male parent are 0.519 1 and 0.555 1, which less the genetic similarity between the parents (0.612 0).The effective number of alleles, expected heterozygosity and shannon's information index among 5 hybrids were 1.550 1, 0.320 0 and 0.472 0 respectively, which also greater than the corresponding values (1.390 7, 0.195 4 and 0.270 8 respectively) between the parents evidently.From these datas, it can conclude that the hybrid can enhance the genetic diversity of P.haitanensis and produce distinct heterosis.From these datas, it also can find that the genetic distances between the 5 hybrids and female parent and male parent are no equality, all secund to the female parent, the reason maybe is the cytoplasmic gene also participate in the expressing and regulation of P.haitanensis genetic characters.At last, the application of ISSR method in fo recasting heterosis was discussed.