Studies On The Genetic Diversity Of Kenaf Germplasms And Its Molecular Markers

Eighty-four kenaf germplasms were conducted to investigate the charactersof morphology, cytology and genetic polymorphism with ISSR and SRAP molecularmarkers. The results showed as follows.1,84 kenaf germplasms were evaluated basing on the analyses of main componentsand two-dimensional cluster, among which the cultivars of Fuhong992, Fuhong2-1and Fuhong02/11 were qualified as high-yield and good-quality varieties. Thaihong763 and Fuhong 5 were good at fiber quality with more than 300 fiber indexes.The seed and chromosome satellite of Alian were enormous. The morphological traitsof variety 85-244 were qualified as claw leaves, small flowers and deep leaf split.While the variety of H094 with blue corolla, helix petal and outer stigma presentedstrong resistance. The germplasms discussed above could be used as favorablematerials in kenaf breeding. According to the analysis of principle components,the breeding materials with higher plant height, mediate stem perimeter, thickerbast fiber, higher rate of bast fiber to stalk, should be selected to resolvethe conflict between quality and yield in kenaf breeding.2,The analysis of chromosomes in 11 kenaf germplasms showed that the numberof chromosome was the same (2n=36) in all materials, and there were 4 kinds ofchromosome types with the centromeres at middle or sub-middle. The ranges ofchromosome comparative and actual length were 3.48%-9.82% and 1.85μm-7.00μmrespectively, and the asymmetry coefficient of chromosome type was 53.5%-58.6%.The analysis also revealed that there were 2 pairs of satellites in kenafchromosome, one was ordinary, whilst the other could be divided into ordinary,bigger and super big types according to its size, suggested that it would be auseful marker in cytological study of kenaf.3. Twenty-eight ISSR polymorphic primers were selected from 80 primers, mostof which were repeat sequence of 2 nucleotides. There were more (AC)n and (CA)nand they produced more polymorphic bands, which indicated that TG or GT wereabundant in genome of kenaf. The genomic DNAs of 84 varieties were amplified byPCR with 28 polymorphic ISSR primers, which produced 230 bands from 400bp to2000bp(8.21 bands per primer in average), and 185 bands were polymorphism, therate of po]ymorphism was 80.43%. The number of polymorphic bands each primerproduced was from 4 to 11. Twenty-six polymorphic SRAP primers were selected from 225 primercombinations, with which the genomic DNAs of 84 varieties were amplified by PCR.329 bands from 300bp to 1500bp were produced (12.7 bands per primer in average),among which 248 bands were polymorphic, and the rate of polymorphism was 75.4%.The number of polymorphic bands each primer produced was from 5 to 15.4. A good system of SRAP technology was founded. It included 20ng DNA, 2.5mmolMg²⁺, 150umol dNTPs, 1.5U Taqase and 5μm each primer, and the first and secondannealing temperature were 37℃and 55℃.5. The coefficient of genetic similarity between ISSR and SRAP technology was0.91137(n=3486), and the correlation was significantly. So the study on geneticdiversity in kenaf genome with ISSR and SRAP technology was creditable andscientific, and the results of two methods were coherency.The combination of ISSR and SRAP research indicated the 20 wild varietiesshould be divided into 8 wild and 12 semi-wild varieties, and the cultivar Tashkentwhich was introduced from Soviet last century should be a semi-wild variety. Atthe level of 20% based on the different coefficient, 84 kenaf varieties can bedivided into two groups: wild varieties, semi-wild varieties and cultivars. Amongwhich the wild variety from Tanzania was original and ancient. At the level of13% based on the different coefficient, and cultivars were distinguished. Thesemi-wild varieties were divided into 4 sub-groups, and the cultivars were dividedinto 7 sub-groups. The difference among different group or sub-group was obvious.6. This study put forward that kenaf species should be divided into wildvariety and cultivars. Among cultivars, there are 8 variation and 16 type, 5variation and 11 type of which were named by Howard, and 3 variation and 5 typewere new discovery of our study.7. This research supported the point that kenaforiginated from Africa. EastAfrica should be the main originate center. According to the continents theoryand the classifiing result of molecular markers, we presumed that the wild andsemi-wild varieties spread to Northwest Africa, Northcenter Africa, South Africaand the world through three different ways. The spread ways of cultivars aremanifold. They were introduced to Asia and Europe from Africa, and spread toAmericas and Europe from Asia, and the cultivars of Americas spread to Asia, Europeand Africa, forming a large global cycle. Because of the global cycle and mostof cultivars were generations of E1 Salvador and other several ancient varieties,the genetic diversity between the cultivars from different origins is rare.