| Saccharina japonica “Haitian No.1” was a new variety which has a heavier individual weight, higher temperature tolerance and earlier mature compared to the control variety. The new variety was screened out for several years after hybridization between parents which were the north cultivar with high yield and the south cultivar with strong high-termperature tolerance.In this paper, the biological characteristics of S. japonica “Haitian No.1” was investigated by using the physiloligcal and molecular methods. The physiological experiment including that using liquid-phase oxygen measurement to research the photosynthesis and respiration of the new variety under different growth environment, using chlorophyll-fluorescence techniques to research the optimal maximum quantum yield(Fv/Fm) of PhotosystermⅡ(PSⅡ) under high temperature, and nutrition assessment on four new S. japonica varieties; the molecular experiment is about, genetic diversity analysis with simple sequence repeat(SSR) and quantitative-PCR of the heat shook protein(Hsp) of S. japonica. The results showed that:(1) The maximum length and width of “Haitian No.1” were about 4 m and 0.65 m respectively, all of which were better than the control. The length and daily growth rate decreased n May and June in Rongcheng, The yield of “Haitian No. 1” in Dalian was higher than that in Rongcheng,and the blade length was stable in Dalian during April to June.(2) The nutrition composition of 3 new edible S. japonica varieties of “Haitian No.1”, “Haitian No.2”, “Haitian No.3” and Kjellmaniella crassifolia were analyzed. The results indicated that the contents of crude protein, alginate and mannitol in general nutrients of S. japonica were higher. The composition of crude protein(10.7%) in “Haitian No.1” and “Haitian No.2” was highest. The content of crude fat(0.3%) in “Haitian No.3” was least. The contents of iodine and alginate(0.47%, 28.2%) in “Haitian No.1” were highest in 4 S. japonica varieties. The analysis of amino acid composition showed that the content of total amino acids(TAA) in all S. japonica varieties was 5% to 6%, and essential amino acids accounted for 30% to 40% of total amino acids(EAA/TAA). The compositions of calcium, magnesium and iron were higher than others mineral elements.(3) We explored the influence of different environmental factors on the “Haitian No.1”, and the results indicated that the maximum value of relative growth rate(RGR) and net photosynthesis(Pn) was at 14°C, 80 μmol photons/(m2·s) light intensity, 6 mg/L nitrogen concentration(N: P = 10: 1, the same below). The growth of sporophytes was inhibited at 22 °C, and RGR of which was significantly lower than that of 14 °C group(P<0.05). RGR at 20 μmol photons/(m2·s) was significantly lower than that at 80 μmol photons/(m2·s)(P<0.05). As the temperature, light intensity and nutrient concentration increased, Pn increased at first and then decreased. Pn at 14 °C temperature was significantly higher than that of other groups. And Pn at 4, 6 mg/L was significantly higher than that at 2, 8 and 10 mg/L group(P<0.05). Respiration rate(R) was inversely correlated with Pn under conditions of the experiment. Temperature and nutrient concentrations had more impact on P/R(total photosynthetic rate / respiration rate) than light intensity. Orthogonal test results showed that the suitable culture conditions for sporophytes of “Haitian No. 1”were 50 μmol photons/(m2·s), 16 °C, 6 mg/L nitrogen concentration.(4) In this study,we selected 8 pair primers of the simple sequence repeat(SSR) molecular markers we used to test 120 samples of 4 S. japonica varieties. From 20 pair of SSR primers published online, 8 pairs were screened out as they have good amplification patterns on most of 120 DNA templates. The results showed that 28 polymorphic alleles and 9 specific alleles were detected by eight SSR markers, and the average alleles were 4.625 per pair of primers. The Nei’s gene diversity(H) and the Shannon index(I) of 4 S. japonica was 0.3809 and 0.6702 respectely, which showed that the genetic diversity of 4 S. japonica was relatively lower. Among them, the value of Nei’s gene diversity and Shannon’s information index of “Haitian No.1” was the highest, and the number of polymorphic alleles was the maximum. This indicated that the genetic diversity of S. japonica of “Haitian No.1” was higher than the other three S. japonica varieties. The level of genetic diversity of “Haitian No.2”、“Haitian No.3” and “Huangguan No.1” was decreased successively. Cluster analysis demonstrated that the relationship between “Haitian No.1” and “Haitian No.3” was clost, the relationship between “Haitian No.1” and “Huangguan No.1” was furthest. Analysis of molecular variance(AMOVA) revealed that about 92.06% of variations were derived from individuals of four S. japonica varieties, while 7.94% of variations resided among four S. japonica varieties. The genetic diversity of “Huangguan No.1” was the minimum, needing to strengthen on biodiversity protection; the highest genetic diversity was in “Haitian No.1”, suitable for excellent new variety breeding.(5)The effects of high temperature(25℃) stressed on chlorophyll fluorescence parameters and heat shock proteins of sporophytes and gametophytes of S. japonica. After 36 h under the high temperature, the Fv/Fm was declined as time went on and which was closed to zero at 72 th hour, which indicated that the algae was dead. The degree of sensitivity of different gametophytes of S. japonica was different when cultured in high temperature, and varieties of S. japonica 1, 2 and Kjellmaniella crassifolia were sensitive to high temperature. The expression of sj HspP70-1 and sjHsp70-2 of sporophytes was increased as time went on and sjHsp90-1 was reversed after 12 h when cultured in high temperature. The expression of three Hsp genes rose as time went on after 36 h cultured in different temperature, while the expression of sjHsp70-2 was at the same level under the 6, 10 and 14℃. The expression of sjHsp70-1 was higher than the others when cultured in different temperature. |
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