| Undaria pinnatifida is the important macroalgae for the economic benefits andthe demands are increasing year by year. One of the key factors to develop theindustry of Undaria pinnatifida cultivation is seedlings quality. The effective methodto improve the industry of Undaria pinnatifida cultivation is to cultivate new varieties.Compared with the traditional method of breeding, the haploid cloning hybridizationis the efficient way to breed. This article treats the breeding of variety as the startingpoint to carry out three following experiments and is expected to provide foundationaldata for the crossbreeding of Undaria pinnatifida.1. The optimization of the culture condition of the gametophyte cloning of Undariapinnatifida from Sanriku, Japan.The experiment was divided into two steps. At first the temperature andillumination intensity that can influence the growth of the gametophyte clone ofUndaria pinnatifida were optimized. The temperature and illumination intensity wereset up by four gradients respectively which are18℃,21℃,24℃,27℃and2500lx,4000lx,5500lx,7000lx. The complete cross grouping was adapted in this experiment.The total of the treatments is16.The result indicated that the external environmental factors—temperature andillumination intensity influenced the growth of the gametophyte tremendously. Thefactors interacted each other and influenced the growth of the gametophytetremendously too. But the single factor influenced differently. The optimal conditionto culture the gametophyte in the laboratory was21℃and2500lx. The growth rate ofthe cell of the gametophyte clone was maximum between the fifth day and the tenthday after cultivated. So the subculture was carried out on the tenth day in order tokeep the growth rate higher.On the basis of the first step, the further optimization influenced the method tocultivate the gametophyte and the initial inoculation density. Finally the optimaltemperature, illumination intensity, cultivation method and inoculation density were determinated to culture the gametophyte clone of Undaria pinnatifida. Three culturemeans including stewing, aeration and magnetic force stir were set up and six gradesof the inoculation density are set up by0.1,0.2,0.4,0.6,0.8and1.0g/L. Thecomplete cross grouping was used and the total of the treatment was18. The resultindicated that the cultivation method and the initial inoculation density influenced thegametophyte growth greatly and the interaction existed. But the influence of thesingle factor expressed some variation. The optimal condition was the initialinoculation density of0.1-0.2g/L under aeration. So in this experiment, the optimalcondition to cultivate the female gametophyte clone from Sanriku, Japan was thetemperature of10℃, the illumination intensity of2500lx and the initial inoculationdensity of0.1-0.2g/L under aeration.2. The study on the applicability of applying SSR of Laminaria japonica to analyzeUndaria pinnatifidaTo obtain SSR marker to study the germplasm structure and genetic diversity,this experiment adopted SSR transfer bewteen related species to analyze theapplication of15SSR primer of Laminaria japonica to Undaria pinnatifida. Theanalysis of variation in38individuals was carried out. The result indicated thatSSR002and SSR115could not amplify the genome of Undaria pinnatifida. SSR194could do but did not have polymorphism. all the other12markers could amplify DNAfrom Undaria pinnatifida and had polymorphism.9markers among them fitted in toHardyWeinberg Equilibrium.34alleles have been detected in these9SSR marker ofLaminaria japonica. The average was3.8in each locus ranging from3to5. Theobserved heterozygosity (Ho), the expected heterozygosity (He) and the informationcontent of polymorphism (PIC) ranged from0.238to1.000,0.500to0.692and0.413to0.780respectively. The polymorphism provided by9loca is higher and could beapplied to the genetic study of Undaria pinnatifida.3. The study on genetic diversity of Undaria pinnatifida populationBy means of SSR marker, the preliminary assessment on the genetic diversity ofthe cultured population and wild population in main producing area provided thereference for the breeding of variety of Undaria pinnatifida in the future.105sites were amplified by29pairs of SSR primers. The number of effective alleles from4populations was1.7438-2.0857. The diversity index (H) was0.3810-0.4541. TheShannon index (I) was0.6211-0.7408. The ratio of polymorphism site was93.10%-100.00%. The wild population from Qingdao had the highest polymorphism.P, H and I were100.00%,0.4541and0.7408respectively. The cultured populationfrom Korea had the lowest polymorphism. P, H and I were93.10%,0.3810and0.6211respectively. Based on the genetic distance between the populations, thedendrogram between populations was built using Unweighted Pair Group MethodWith Arithmetic Mean (UPGMA). AMOVA showed that most of the hereditaryvariation (79.72%) existed in the population. The small part (20.28%) existed betweenthe populations. Gst was0.2133close to Fst (0.2028). The value of gene flow (Nm)was0.9829close to1. The three values demonstrated that the genetic differentiationbetween populations was low. On the whole, the genetic diversity in the populationlay in higher level, while the genetic differentiation between populations was low. |
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