Studies On Improvement Of Shoot-tip Grafting Technology Of Virus Eradication By Inducement The Adventitious Bud With Stem In Citrus

The study was carried on tissue culture experiment of mature citrus stem . The adventitious bud through stem cultivation were used to proceed shoot-tip grafting.Through the method the experiment obtained some survival virus-free plants. The healthy and virulent different citrus breeds' apexes were used as explants to proceed shoot-tip grafting. Furthermore, we identified the generated plantlets by specific PCR. The main results are as follows:1. Through the modified pasteurize method the experiment released pollution rate of the mature citrus segment culture in vitro. It was propitious to improve that: The half senescent stem which were token back from the field at 2 p.m.sunny day in summer were used as explants, the interval 2 days pasteurize method was used and can keep the citrus stem pollution rate under 10%.2. The experiment obtain some apexes in tube by cultivation the mature citrus stem and got some citrus varieties' medium composition of the initially generation. The adventitious bud through stem cultivation were used to proceed shoot-tip grafting and got some survival plants.The survival rate is higher than by the apex from textground in different degree,the higher survival rate reaches 80%.3. To treat the apexes from the field with 6-BA with different concentration for different time, we found that the effect was distinct. It was propitious to improve the survival rate by immersing the apexes with 0.5 to 1mg/L 6-BA for ten minutes,the supreme survival rate reaches 60%.4. To treat the apexes with different variety disinfectant with different concentration for different time,we found that the survival rate of shoot-tip grafting is greatly different.The result showed that the best effect is to treat the apexes with 2% NaClO for 7min.5. The primers of the PCR were designed based on the sequence information of In-2.6 (Gene bank accession number M9491). Polymerase chain reaction(PCR) was performed for detection of the bacteria-like organism(BLO) that caused citrus yellow shoot virus and some survival plants by shoot-tip grafting. By using the PCR procedure, the presence of citrus yellow shoot virus BLO in some citrus' seedlingscould be detected in samples of infected citrus and could not be found in all the plants by STG. It was proved that the STG could eliminate the pathogen of citrus yellow shoot virus from virus-infected apexes. It can be an availability method for propagating virus-free citrus cultivars in the future.