Transformation of Pea Lectin Gene and Parasponia Haemoglobin Gene into Rice and Their Expressions

Lectin and leghemoglobin in legumes play the important roles, respectively, in recognition of host plants to their rhizobial bacteria, and lowering the oxygen partial pressure around bacteroids and protecting nitrogenase from oxygen in symbiotic nitrogen-fixing nodules. In order to extend the host range of the rhizobial bacteria and to make them fix nitrogen in non-legumes, pea lectin gene ( pl ) and Parasponia hemoglobin gene ( phb ) have been constructed into a plant expression vector (pCBHUL) and the vector pCBHUL was introduced into rice calli from immature young embryos by particle bombardment. After the calli were regenerated into plantlets on the resistant-selecting media containing hygromycin, they were identified by PCR and Southern blot hybridization. It was indicated that the pl and phb genes were integrated into nucleic genome of the transformed rice plants. GUS activity and the product of the pl gene were determined by GUS staining, Western blot and in situ hybridization at translational level. Eighteen out of 40 plants resistant to hygromycin were positively identified by PCR analysis with the rate of 45%. The pl gene was expressed in 3 out of 18 plants with 17% and 7.5%in 40 plants. The results may provide a clue for exploring whether Rhizobium leguminosarum bv. viceae could extend its host range and make the transgenic rice plants have the possibility of being symbiotic, or associative to nitrogen fixation.     

Genetic Diversity Within and Among Populations of Viola tenuicornis with Reference to Sampling Strategies

Genetic diversity and population differentiation of Viola tenuicornis W. Beck. were studied in nine populations in Beijing using horizontal starch gel electrophoresis. Allozyme data for 11 loci of 8 enzymes indicated high level of genetic variability in this region with P=72.7％, A=2.4 and H e=0.243. In contrast, the population differentiation was lower than the average of other perennial herb with F st=0.196. It was found that distances among populations had little effect on population differentiation. A sample of 30 individuals could well represent a population, but less than 20 individuals per population might lead to significant bias in the estimation of genetic parameters, in particular the values of A and H e.