Preliminary Study On Mutation And Hybridization Breeding Of Porphyra Haitanensis Strains

Free-living conchocelis of wild Porphyra haitanensis were treated with ⁶⁰Co-? ray in orderto obtain mutations with excellent practical characters. Then crossed experiments between themutations(?) and selected wild strain(?) were carried out. Through cultivated and observed F₁gametophytic blades of hybrids, the pigmentation mutants and crossed strains with heterosiswere picked up. Single cell clone and enzymolysis were used to propagate fast in pure strains ofinduced mutations and hybrids. Moreover, the central practical characters of their offspring wereevaluated and compared. At same time, inter-simple sequence repeat(ISSR) was used in statisticand analyzing amplified bands of parents and hybrids, just expect to analyze and identify filialgeneration quickly and exactly, and provid the theories gist in research of hybridization breedingand heterosis analysis of P. haitanensis on the molecule level.1. Three strains have been selected. The first one was 7-â… which has the quickest growth(6.51±1.39 cm·d^-1, after blade length overed 30 cm), wide blade (2.99±0.61 cm), hightemperature resistant(29℃) and high phycobiliprotein content(104.858±7.376 mg·g^-1) of drysample. The second one was 7-â…¡which has quick growth(4.26±1.23 cm·d^-1, after blade lengthovered 30 cm), thin blades(22.50～27.50μm in the middle part of the blade) and highphycobiliprotein content(104.239±5.064 mg·g^-1) of dry sample. The third one waspigementation mutant, 3-â… , which possessed of purple and filmy blade(25.00～27.50μm)。Itproved that ⁶⁰Co-? ray was a useful mutagen in inducing breeding of P. haitanensis. Whenirradiation rang was about 300～1100 Gy, conchocelis could be induced and represented inoffsprings.2. Filial generation (mutations(?)and selected wild strain(?)) had significant hybrid vigor,not only had parental dominance but heterobeltiosis. Four strains(â…¡,â…¢,â…£andâ…¤) with excellentpractical characters were selected by hybridization breeding. After the thalli (which length wasabout 3～5 cm) were cultivated for ten days, the over-standard heterosis of average daily gaincould reach to 12.35%, 139.78%, 107.57% and 173.52%, and the index of heterosis couldreach to 99.83%, 213.07%, 184.44% and 243.05 % respectively Thereinto, strainâ…¡was stoodout in hih temperature resistant which grew normally in 29℃.3. Brown yellow, emerald and breen pigementation mutants were obtained after crossing.They were low in contents of three phycobiliprotenin (R-phycoerythrin, R-phycocyanin andallophycocyanin) , only about 40.55%～73.17% of maternal. Among them, the thallus of emeraldgrew quickly(7.75±1.78 cm·d^-1, after blades length overed 30 cm). Furthermore, the emeraldconchocelis were easy to mature and had special developmental mode, that was the spherulocytes could develop to sporangial branchlets and conchosporangia without thickconchocelis stage directly.4. ISSR method was used to study the heterosis of the P. haitanensis parents and its fivehybrid strains(â… ,â…¡,â…¢,â…£,â…¤), 21 ISSR primers (were screened from 67 primers) gave riseto 366 discernible DNA bands of which 347 (94.8%) were polymorphic. By statistic andanalyzing these amplified bands, it can find that the average genetic similarity between the 5hybrids and female parent and male parent are 0.5191 and 0.5551, which less the geneticsimilarity between the parents (0.6120). The effective number of alleles (Ne), expectedheterozygosity (h) and shannon's information index (I) among 5 hybrids were 1.5501, 0.3200and 0.4720 respectively, which also greater than the corresponding values between the parentsevidently. From these datas, it can conclude that the hybrid can enhance the genetic diversity ofP. haitanensis and produce distinct heterosis. From these datas, it also can find that the geneticdistances between the 5 hybrids and female parent and male parent are no equality, all secund tothe female parent.