| Plant mutants, which spontaneously produced lesions that resembledisease symptoms in the absence of pathogen attack and other damage orsuppressed conditions, were called lesion mimic. Recently, the researchof these mutants became a focus in fields of plant physiology, molecularbiology and molecular genetics, since it was important for understandingof the development and apoptosis of plants, and the defense-signal systemof disease or stress resistance. Spl5, a lesion mimic mutant of rice, wasidentified from a population of japonica rice Norin8 mutagenized byγradiation. The spl5 mutants, which planted in field, artificial light chest orsterile culture, spontaneously displayed small brown necrotic lesions inall growth stages. Cell death in leaves of spl5 was ascertained by trypanblue stain, and was presumed to have a relationship with the oxidativeburst caused by hypersensitive reaction, since some substances, such asH2O2 and callose, were accumulating in leaves showed by DAB andaniline blue stain. The results also preliminarily showed that the necroticphenotype of could be facilitated by light and high temperature, and theseed germination of spl5 were more sensitive to high temperature andplant grew slowly and was small. Moreover, the spl5 mutants conferredresistance to diverse strains of Xanthomonas oryzae pv. oryzae, includingPXO61, PXO112 and PXO145. Genetic analysis indicated that the lesionmimic trait was controlled by a single recessive locus. In the previous study, spl5 gene has been reported at about 30cM on rice chromosome 7using morphological markers by Iwata (1978). By linkage analysis withSSR markers on the Classical Genetic Map, the spl5 gene waspreliminarily mapped in genetic region of 3.3cM, between two markerRM6574 and RM8247. Further, 65 STS markers were designed based onthe genomic sequence of Nipponbare, and F2 population crossed by spl5and 9311 were used for fine mapping. The spl5 gene was finnaly mappedin physical region of 134kb, between marker SSR41 and RM7121. Geneprediction analysis found 33 predicted ORFs in the 134-kb region. Withthe achievement of this study, it laid a good foundation for the next-stageresearches of cloning and functional analysis of the spl5 gene.Camellia japonica L., a piece of rare flowers in China, is abundantin variety and difficult to classify and identify. In order to find atechnique for classification and identification of Camellia japonica L. inDNA level, the optimal condition of DNA extraction and RAPDamplification system were specially studied. In the experiment, thegenomic DNA obtained from leaves by the method of modified CTAB(with 4％β-Mercaptoethanol and 2％PVP in the DNA extractingsolution) had a fine purity and a good integrity of fragments. For theRAPD amplifying conditions of Camellia japonica L., the perfectreaction system in a 20μL volume was considered to be 100ng templateDNA, 1×Buffer, 1.2mM Mg2+, 125μM dNTP (each), 0.5μM primer and 1U Taq DNA polymerases. The anneal temperature was about 37℃,being adjusted lightly according to the different arbitrary primers. Usingthe reaction system of RAPD above, three new mutational varieties ofCamellia japonica L., "China-America Hong", "Hua Feizhua Furong"and "Yudan" were analysis by RAPD technology. Three valid arbitraryprimers were screened out for RAPD amplification, and of the total 29RAPD bands, 15 ones were polymorphic. Especially primer S1 and S4,which have good polymorphic bonds among varieties, so that it couldwell tell the genetic relationship between the mutational and the originalvarieties. This gave a new standard for identification of the three newmutational varieties of Camellia japonica L. |
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