| Apomixes is a special reproductive way in which seed is formed without the union of male andfemale gametes. It has great potential value in crop breeding, and it attracts great attention on the studyof its genetic mechnism. It was found that apomixis germplasm resources are rich in ramie. In order toanalyze the genetic origin of apomixes type and to provide the theoretical basis for further research, thispaper is concerned with three levels of apomixes, such as cytogenetics, embryology and molecularbiology, using six kinds of ramie material.The karyotype analysis showed that the chromosome number of the two reproduction types in B.tricuspis are both2n=28, in B. longispica, B. silvestrii, B. formosana and B. gracilis are2n=42, and in B.spicata is2n=56. Besides, it is said that there is a type in B. tricuspis that the chromosome number is2n=42. In B. silvestrii, B. formosana and B. gracilis, there is a pair of obvious abnormal chromosomesrespectively. Based on the results of the karyotype analysis and the observation on morphology, wethink that the two reproduction types in B. tricuspis, B. longispica and B. silvestrii, B. formosana and B.gracilis may be have the intimate relationships.Cytoembryological studies were carried out to determine the apomictic mechanisms of the sixkinds of ramie material. All of them are diplospory, B. longispica, B. silvestrii and B. formosana showedthe same mode of embryo sac development that conforms Taraxacum-type, B. gracilis has the similarmodes as the B. tricuspis’s, being deduced to be of Antennaria-type. The B. spicata’s has the biggestdifferences from others’.The cluster analysis based on SRAP data of six ramie materials showed that: the two reproductiontypes in B. tricuspis, B. gracilis and B. spicata are classified into a group, B. longispica, B. silvestrii andB. formosana are classified into a group. And the two reproduction types in B. tricuspis, B. gracilis andB. spicata, B. longispica and B. silvestrii are more intimate. |
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