RESUMO
Soybean mosaic virus (SMV), belonging to the genus Potyvirus of the family Potyviridae, has a relatively narrow host range almost exclusively confined to leguminous hosts. While disease management through genetic transformation can be an effective approach, soybean remains recalcitrant to routine genetic transformation. In this context, it is important to identify new hosts for SMV that can be used to develop effective transgenic resistance strategies. Transformation in Nicotiana benthamiana is simple and highly efficient; hence, here we demonstrate the infectivity of SMV strain SC7 in N. benthamiana plants. To identify an SMV strain infectious in N. benthamiana, we mechanically inoculated N. benthamiana plants with 37 isolates from 21 (SC1 to SC21) SMV strains. Plants inoculated with isolates of strain SC7 produced mosaic symptoms on leaves. However, N. benthamiana plants inoculated with the 20 other SMV strains showed no visible symptoms. Furthermore, soybean cv. Nannong 1138-2 inoculated with sap prepared from symptomatic N. benthamiana leaves showed typical SMV mosaic symptoms 2 weeks after inoculation. In addition, SMV was detected in symptomatic N. benthamiana and soybean leaves by RT-PCR, DAS-ELISA, and further identified by sequencing. Together, the results indicate that N. benthamiana plants could support multiplication of SMV strain SC7. The findings of this study would be useful for the investigation of SMV resistance using the model plant N. benthamiana.
RESUMO
From 1,417 leaf samples with Soybean mosaic virus (SMV)-like symptoms collected from about 1,500 fields of 117 counties of 13 provinces in Southern China during 2004 to 2006, 201 SMV isolates were obtained after biological purification with single-lesion isolation and serological determination. Based on disease reactions on 10 differentials used in China as a representative from various reported differential cultivar systems, the isolates were grouped into 12 strains. Among them, eight were the same as those previously reported from Northeast China and the Huang-Huai Valleys while the other four were new and were designated as SC18, SC19, SC20, and SC21. Strains SC15 and SC18, which were predominant and widespread in Southern China, accounted for 32.3 and 26.4% of the total isolates and were distributed in 9 and 10 provinces, respectively. Thus far, 21 strains have been identified in the three soybean-producing regions in China under the uniform differentials system. According to their responses on the 10 differentials, the strains were clustered into five groups at similarity coefficient 0.6. Among them, SC15 in cluster V is the most virulent strain because it infects all differentials. Therefore, specific attention should be placed on control of its prevalence in soybean production.
RESUMO
An acid-dye colorimetric method was reported for the determination of total alkaloids in 53 samples of Baibu drugs from their growing destricts in 14 provinces and municipalities and its average recovery and its linear range were 96.1% (CV less than 4%) and 20-150 micrograms respectively. The relationship between the total alkaloid content, geographical origins and morphology were discussed. The results showed that: 1. the content of total alkaloids of stemona was 0.26-3.1%; 2. that of Stemona sessilifolia was 0.26-2.17% with the highest content of the sample from Nanyang country in Henan Province; 3. that of S. japonica was 0.83-1.43%; 4. that of S. tuberosa was 0.53-3.1% with the highest content of sample from Hengyang in Hunan Province; 5. that of S. parviflora was 0.22-0.74% with the highest content of sample from Qongzhong in Hainan Province; and 6. that of more yellow, solider and stronger samples was higher than that of any other samples. However, that of all bigger samples in shape was not higher than that of smaller ones.