| In order to provide new evidence for the study of origin and evolution of jute cultivars,genetic diversity among 27 accessions of Con~horus,including 8 wild species,7 close wild species,8 cultivars of C.capsularis and 4 cultivars of C. olilorius,collected from China,India, Africa and other place,were investigated with the technique of RAPD and ISSR analysis. Major results are as follows: (I )An optimized PCR reaction system for RAPD analysis was established: PCR was performed in a 25.tl reaction mixture with 30-6Ong DNA, lSOpmoVl of each dNTP 0.2.tmolIl random primer, I0mmolll Tris-HC1 (PH8.0), SOmmol(l KCI, 2.5mmolIl MgCl2,andl .5U Taq polymerase. The temperature profile used for PCR was 940 for 5 mm, followed by 41 cycles of 94C for 3Osec, 370C for 90sec, and 72C for 1mm, and was terminated with a 7 mm DNA extension step at 72C. (2) 329 and 283 DNA bands were amplified with 25 RAPD and 25 ISSR primers among which 294 (89.36%) and 262 (92.58%)were polymorphic respectively. (3) UPGMA cluster analysis was carried out using software Bio ID++. Two dendrograms were constructed based on the RAPD and ISSR data respectively. According to the trees the accessions could be clustered into two groups (cultispecies and close wild species Vs.wild species) at the level of D=0.785 of the first classification. The results indicate that two cultispecies and their close wild species are obviously different from wild species genetically. At the levels of D=0.850 and D=0.885 of the second classification, the accessions could be clustered into ten groups. Each group might represent a species.It could be drawn from the dendrograms that the two cultispecies C. capsularis and C.olitorius have high genetic similarity and so probably have the same ancestor.(4)There was a high correlation between the two sets of similarity parameters calculated with RAPD and ISSR data respectively (r =0.95477>r 0.01, n= 349), indicating that the two methods were highly consistant and suitable for detecting genetic diversity in jute.(5) Cluster analysis based RAPD and ISSR data show that C. trilacularis2 IC should be a subspecies of C. trilacularis.And the three accessions Kaiyuan C. aestuans,Nianniancai,Zhangpu C. aestuans should belong the same species and therefore could be named C.aesluans altogether. The issues of DNA extraction quality in jute,consistency between RAPD and ISSR markers, genetic diversities and classification position of Tianma and C.urtic?foIius were discussed. Besides, the origin and evolution of Corchorus cultispecies were investigated,according to the modern biological concept of species, archaeology, history and plant geography. It was concluded substantially that C.capsularis was originated in China. |
