Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/7/2012
Publication Date: 8/30/2012
Citation: Walter, A.J., Duan, Y., Hall, D.G. 2012. Titers of 'Ca. Liberibacter asiaticus' in Murraya paniculata and Murraya-reared Diaphorina citri are much lower than in citrus and citrus-reared psyllids. HortScience. 47:1449-1452. Interpretive Summary: Huanglongbing is a serious disease of citrus associated with the bacteria Candidatus Liberibacter asiaticus and vectored by the Asian citrus psyllid in Florida. Orange jasmine is a popular ornamental plant of concern because it can be an alternative host for both the insect vector and the bacteria. We compared the bacterial titers of orange jasmine bushes and orange trees grown in the same field and Asian citrus psyllid reared on infected orange jasmine or citrus. We found that infected orange jasmine plants have about 10,000 times fewer bacteria than infected orange trees and that psyllids reared on infected orange jasmine have about 10,000 times fewer bacteria than psyllids reared on infected citrus. These results show that orange jasmine may be resistant to the bacteria, and that it may not be an important source of the disease for citrus groves.
Technical Abstract: Huanglongbing, one of the most devastating diseases of citrus, is associated with the bacterium Candidatus Liberibacter asiaticus vectored by the Asian citrus psyllid, Diaphorina citri, in North America. Murraya paniculata is a common ornamental plant that is an alternate host of Ca. L. asiaticus and D. citri. We tested M. paniculata and Citrus sinensis grown in the same field for their titer of Ca. L. asiaticus. We also assayed D. citri from colonies on Ca. L. asiaticus-infected M. paniculata and Citrus sp. We found the bacterium in both plant species, but the titer was four orders of magnitude lower in M. paniculata than in Citrus. Psyllids reared on infected M. paniculata also carried bacterial titers four orders of magnitude lower than psyllids reared on infected Citrus sp. These observations question the importance of M. paniculata as a reservoir of huanglongbing and indicate resistance to huanglongbing in M. paniculata.