We evaluated the role of pre-culture on survival rate of in vitro apple plants treated by thermotherapy. Two apple cultivars, Malusxdomestica cv. Pink Lady and Huafu, were used in the experiment and both have widely g...We evaluated the role of pre-culture on survival rate of in vitro apple plants treated by thermotherapy. Two apple cultivars, Malusxdomestica cv. Pink Lady and Huafu, were used in the experiment and both have widely grown in China and infected with Apple chlorotic leafspot virus （ACLSV） and Apple stem grooving virus （ASGV）. Results in growth and virus titer of apple plants did not exhibit clear trends during five different periods of pre-culture. Whilst, pre-culture increased the survival rate of the two cultivars during thermotherapy. The survival rate of plants pre-cultured for 13 d （P-13d） was 14 and 51% higher than that of P-ld plants for Pink Lady and Huafu, respectively. Moreover, pre-culture positively influenced regeneration of Huafu plants. The average survival rate of plants regenerated from P-ld and P-4d was 20% lower than that regenerated from P-7d, P-10d, and P-13d. The efficiency of virus eradication was determined by reverse-transcription PCR with two primer pairs for each virus, and the detection results showed that pre-culture scarcely affected apple virus elimination. Despite the fact that the two viruses were hardly detected at 5 d of thermotherapy, no virus-free plants were found in the two cultivars of regenerated apple plantlets after 30-d treatment.展开更多
A novel phytoplasma was detected in a cherry plum（Prunus cerasifera Ehrh） tree that mainly showed yellow leaf symptom. The tree was growing in an orchard located in Yangling District, Shaanxi Province, China. The le...A novel phytoplasma was detected in a cherry plum（Prunus cerasifera Ehrh） tree that mainly showed yellow leaf symptom. The tree was growing in an orchard located in Yangling District, Shaanxi Province, China. The leaves started as chlorotic and yellowing along leaf minor veins and leaf tips. Chlorosis rapidly developed to inter-veinal areas with the whole leaf becoming pale yellow in about 1-4 wk. Large numbers of phytoplasma-like bodies（PLBs） were seen under transmission electron microscopy. The majority of the PLBs was spherical or elliptical vesicles, with diameters in range of 0.1-0.6 μm, and distributed in the phloem cells of the infected tissues. A 1 246-bp 16 S ribosomal RNA（rRNA） gene fragment was amplified from DNA samples extracted from the yellow leaf tissues using two phytoplasma universal primer pairs R16mF2/R16mR1 and R16F2n/R16R2. Phylogenetic analysis using the 16 S rRNA gene sequence suggested that the phytoplasma associated with the yellow leaf symptoms belongs to a novel subclade in the aster yellows（AY） group（16SrI group）. Virtual and actual restriction fragment length polymorphism（RFLP） analysis of the 16 S rRNA gene fragment revealed that the phytoplasma was distinguishable from all existing 19 subgroups in the AY group（16SrI） by four restriction sites, Hinf I, Mse I, Sau3 A I and Taq I. The similarity coefficients of comparing the RFLP pattern of the 16 S rRNA gene fragment of this phytoplasma to each of the 19 reported subgroups ranged from 0.73 to 0.87, which indicates the phytoplasma associated with the cherry plum yellow leaf（CPYL） symptoms is probably a distinct and novel subgroup lineage in the AY group（16SrI）. In addition, the novel phytoplasma was experimentally transmitted to periwinkle（Catharanthus roseus） plants from the tree with CPYL symptoms and then back to a healthy 1-yr-old cherry plum tree via dodder（Cuscuta odorata） connections.展开更多
基金supported by the Agricultural Science and Technology Innovation Program of the Chinese Academy of Agricultural Sciences (CAAS-ASTIP)
文摘We evaluated the role of pre-culture on survival rate of in vitro apple plants treated by thermotherapy. Two apple cultivars, Malusxdomestica cv. Pink Lady and Huafu, were used in the experiment and both have widely grown in China and infected with Apple chlorotic leafspot virus （ACLSV） and Apple stem grooving virus （ASGV）. Results in growth and virus titer of apple plants did not exhibit clear trends during five different periods of pre-culture. Whilst, pre-culture increased the survival rate of the two cultivars during thermotherapy. The survival rate of plants pre-cultured for 13 d （P-13d） was 14 and 51% higher than that of P-ld plants for Pink Lady and Huafu, respectively. Moreover, pre-culture positively influenced regeneration of Huafu plants. The average survival rate of plants regenerated from P-ld and P-4d was 20% lower than that regenerated from P-7d, P-10d, and P-13d. The efficiency of virus eradication was determined by reverse-transcription PCR with two primer pairs for each virus, and the detection results showed that pre-culture scarcely affected apple virus elimination. Despite the fact that the two viruses were hardly detected at 5 d of thermotherapy, no virus-free plants were found in the two cultivars of regenerated apple plantlets after 30-d treatment.
基金supported by the 111 Project from the Ministry of Education of China (B07049)the PhD Program Foundation from the Ministry of Education of China (20100204110004)the National Natural Science Foundation of China (31371913)
文摘A novel phytoplasma was detected in a cherry plum（Prunus cerasifera Ehrh） tree that mainly showed yellow leaf symptom. The tree was growing in an orchard located in Yangling District, Shaanxi Province, China. The leaves started as chlorotic and yellowing along leaf minor veins and leaf tips. Chlorosis rapidly developed to inter-veinal areas with the whole leaf becoming pale yellow in about 1-4 wk. Large numbers of phytoplasma-like bodies（PLBs） were seen under transmission electron microscopy. The majority of the PLBs was spherical or elliptical vesicles, with diameters in range of 0.1-0.6 μm, and distributed in the phloem cells of the infected tissues. A 1 246-bp 16 S ribosomal RNA（rRNA） gene fragment was amplified from DNA samples extracted from the yellow leaf tissues using two phytoplasma universal primer pairs R16mF2/R16mR1 and R16F2n/R16R2. Phylogenetic analysis using the 16 S rRNA gene sequence suggested that the phytoplasma associated with the yellow leaf symptoms belongs to a novel subclade in the aster yellows（AY） group（16SrI group）. Virtual and actual restriction fragment length polymorphism（RFLP） analysis of the 16 S rRNA gene fragment revealed that the phytoplasma was distinguishable from all existing 19 subgroups in the AY group（16SrI） by four restriction sites, Hinf I, Mse I, Sau3 A I and Taq I. The similarity coefficients of comparing the RFLP pattern of the 16 S rRNA gene fragment of this phytoplasma to each of the 19 reported subgroups ranged from 0.73 to 0.87, which indicates the phytoplasma associated with the cherry plum yellow leaf（CPYL） symptoms is probably a distinct and novel subgroup lineage in the AY group（16SrI）. In addition, the novel phytoplasma was experimentally transmitted to periwinkle（Catharanthus roseus） plants from the tree with CPYL symptoms and then back to a healthy 1-yr-old cherry plum tree via dodder（Cuscuta odorata） connections.
