Search

Grafting is a commonly used method for citrus propagation and transmitting 'Candidatus Liberibacter asiaticus' (CLas), the putative causing agent of citrus Huanglongbing (HLB). Optimization of the grafting inoculation methods facilitates the material preparation in HLB research. Citrus buds with CLas were grafted onto healthy sour tangerine (Citrus sunki Hort. ex Tanaka) seedlings by different methods such as top grafting ('T' grafting and 'V' grafting) and side grafting (abdominal grafting). Along with the symptom observation, titers of CLas in the leaves were detected by RT-qPCR monthly. The correlation between the growth status of buds or different grafting methods and the success rate of HLB transmission were analyzed. Our results suggest that sufficient DNA could be extracted to accurately detect the CLas from even only 0.0125 g leaf midrib or branch bark. The probability of CLas transmission was higher in plants inoculated with buds in better growth conditions. The success rate of 'T' grafting was significantly higher than that of side grafting and 'V' grafting. Additionally, in terms of HLB transmission efficiency, the two-bud grafting scheme was superior to the single-bud and three-bud grafting schemes. In conclusion, the grafting combinations with the highest HLB transmission efficiency were screened to provide a methodological reference for the practice or research of grafting to obtain plant material.