| Xinjiang wild rape( "wild rape" for short in this paper) is a Cruciferae wild rape resource growing widely in Chinese Xinjiang region. The objective of this program was to make clear the genetic relationships between wild rape and some Brassica species, and to probe the status of wild rape in Brassica evolution by means of RAPD, morphology, interspecific hybridization and Fi pollen mother cell (PMC) meiosis analyses. Fourteen plant materials were used .. . in this study including five wild rape lines,three B. napus varieties, two B. juncea varieties, two B. campestris varieties, one B. nigra variety and one unidentified material.The main results obtained are as follows:l.RAPD analysisa. Quality and yield of DNA: All fourteen DNA samples were qualified for RAPD analysis with 20kb or so sizes, 1.9308-2.0592 OD260/OD280 values andnearly free RNA. The DNA yield spectrum was 76.0-478.1 ug/g(fresh weight).b. Optimal PCR parameters:The optimal reaction system was composed of1.6unit/30ul Taq DNA polymerase, 0. 3umol/L primer, IXbuffer, 2mmol/L Mg , 0. 2mmol/L dNTPs and 40ng/30ul template.c. screened primers: 100 primers were tested,and 14 of them were used as valid ones for RAPD analysis.d. Traits of PCR products: 129 bands were obtained from 14 DNA samples using the screened primers, averaged 9. 21 bands per primer. Among the 129 bands, 112 (86.82%) were polymorphic, and 17 (13.18%) were monomorphic. Single primer created 7-12 total bands and 5-11 polymorphic bands. The sizes of 129 bands varied from 350bp to 1500bp,most of them were 500-lOOObp.e. Genetic distances and clustering result: The genetic distances among 14 plant materials vibrated from 0. 0509 to 0. 8229. Wild rape-? nigra showed a minimal genetic distance, then wild rape-#. juncea ,then wild rape-#. napus, and wild rape-/?, campestris showed the maximum. The fourteenplant materials were classified into five groups by a joint distance ofin0.1086-0.2024, and each group represented a species . It was clear that the unidentified material "Ye 4" is in fact B. juncea . In the dendrogram, five wild rape lines clustered together at first, then clustered with B.nigra and B. juncea, finally with B. napus and B. campestris, which revealed that the species of wild rape shares the same evolutional route with B.nigra and B. juncea.f. Origin and evolution of wild rape: It was made clear from above RAPD analysis that wild rape is a more primordial species than B.nigra. A hypothesis on the Origin and evolution of wild rape was presented in this paper. In this hypothesis, wild rape(n=9) was on a transitional evulutiqr.i stage between its ancestor(n=5, 6 or 3) and B. nigra(n=8).2. Morphological studya. Growth duration expression: Growth duration of wild rape was very close to that of B. nigra and B. juncea.b. Morphological traits: Many morphological traits of wild rape were very similar to that of B.nigra and B. juncea. This result verified by means of morphology that wild rape showed a closer genetic relationship to B.nigra and B. juncea than to B. napus and B. campestris.3. Interspecific hybridization studya.Self-compatibility: In five wild rape lines,one expressed level-one self-compatibility, the other four expressed Self-incompatibility. B.nigra showed low-degree self-compatibility. B. campestris showed self-incompatibility. B. juncea and B. napus showed self-compatibility.b. Interspecific hybridization compatibility: Interspecific hybridization between wild rape and four Brassica species showed high-degree incompatibility, all of the hybridization-compatibility-indices were below 0. 1. Relatively, wild rapeXB. nigra showed the highest "index" , then wild rapeX B. juncea, then wild rapeX B. napus , and wild rapeX/?. campestris showed the lowest one, which verified the RAPD result once more. On the other hand, although wild rape and B.nigra made the relatively highest "index" ,they still expressed high-degree incompatibility,which indicated that there were a very long evolutional process from wild rape...
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