| Arthrospira is a group of photosynthetic autotrophic prokaryote, which has existed on the earth for 35 hundred million years. It contains abundant nutritional ingredients and physiological active materials; therefore it has a bright prospect for exploitation. A. platensis (A2) in Chad Lake in Africa and A. maxima (A3) in Texcoco Lake in Mexico are mainly in investigation and commercialization at present. These two Arthrospiras grow well in high temperature.In 1996 three species of Arthrospira and a species of Spirulina were found in the alkaline lake of Erdos Plateau by Prof. Qiao Chen et al. In recent years many studies about A1, which is mainly about morphology anatomic structure and physiological biochemical character, has been reported. But there is little report about genetic diversity. AFLP analyses about genetic diversity and relationship of 4 samples of Arthrospira have not been found in papers.In this paper, technique of AFLP molecular marker and the observation of morphologic characteristics were used to reveal the differences and respective characteristics of A1, A2, A3 and A4, using both molecular and morphological levels to probe their genetic diversities, evolutionary status and relationships. The author wants to enrich and consummate the basic investigation of Arthrospira which is meaningful to protect and utilize the genetic diversity of Arthrospira germplasm resource in Erdos Plateau.The AFLP results showed that twelve pairs of selected AFLP primer were used to amplify the genome DNA of 4 samples of Arthrospira, and 487 clear bandings whose sizes are between 25 and 1000bp can be gained. 380 bands of them are polymorphism, and each primer can obtain 32.75 polymorphic bandings averagely. The total sum of the specific bands is A4>A1>A2>A3, which shows that the genetic diversity of local samples A1 and A4 in the alkaline lake of Erdos Plateau is super to exotic ones A2 and A3. The average genetic distance of 4 samples is between 0.3887 and 0.9679, among which the shortest genetic distance is between sample A2 and A3 and the longest genetic distance is between sample A3 and A4. It means that there were some genetic differences among samples. The cluster analysis based on UPMGA and the data of genetic distance indicates that the introduced samples A2 and A3 have the closest genetic relationship, and the A. platensis A1 and A2 have a relatively farther genetic relationship. A4 has a farther genetic relationship with other samples, and the genetic relationship between A4 and A3 is the farthest. The morphologic results showed that by the principal component analysis, distances between the spirals, spirals coil, spirals broad, trichome length and cells long are the main traits, which distinguish 4 samples of Arthrospira. Trichome color and cells broad are the secondary traits. The end of trichome and types of ups and downs have little effect on discrimination. The discriminative analysis revealed that the accurate rate of the discrimination is between 90.0% and 100.0%, and the integrative discriminative rate is 97.0%. The 2D-plot centers of discriminative functions of the 4 Arthrospira samples are remote from each other. Genetic variation was existed in these 4 samples which have morphological difference. The cluster analysis showed that the range of average euclidean distance in 4 samples is between 2.935 and 5.275; the two A. platensis A1 and A2 have the smallest euclidean distance and firstly paired up, then clustered with A3, finally grouped with A4 together. This result is congruent with morphologic cluster analysis but distinctive with AFLP. The author presumes that the different environments and geographical isolation are the primary reasons for the result. The two samples have genetic differentiations which mainly exist in other index outside morphology.
|
PDF Full Text Request