Submitted to: Plant Disease
Publication Type: Peer reviewed journal
Publication Acceptance Date: 11/23/2007
Publication Date: 1/22/2008
Citation: Deng, X., Chen, J., Luo, Z., Feng, Z., Li, H., Civerolo, E.L. 2008. First report of graft-transmission and PCR detection of Candidatus Liberibacter asiaticus from Atalantia buxifolia in Guangdong, China. Plant Disease. 92: 314. Interpretive Summary: Atalantia buxifolia, syn. Severinia buxifolia, is a common landscape and medicinal plant in China. In the U.S., it is called Chinese boxwood, a citrus related landscape plant grown in the coastal areas of the Gulf States and California. By graft transmission and two PCR methods, we report for the first time Chinese boxwood in Guangdong, China , is a host for Candidatus Liberibacter asiaticus, the pathogen of citrus Huanglongbing (HLB) disease. Determination that Chinese boxwood is a host for the HLB pathogen is potentially significant for the epidemiology and control of HLB in citrus-producing areas.
Technical Abstract: Atalantia buxifolia (Jiubingle), syn. Severinia buxifolia, is a common landscape plant and a popular Chinese medicinal herb known as Dongfengjie. It is unclear if this Rutaceous plant is a host for Candidatus Liberibacter asiaticus, the pathogen of citrus Huanglongbing (HLB) in Guangdong, P. R. China. In August of 1994, three A. buxifolia plants adjacent to an experimental orchard of South China Agricultural University at Guangzhou were found showing leaf mottle symptoms. Two buds from each plant were grafted onto each of three mandarin trees (Citrus reticulata cv. Pongan) in a psyllid-proof screenhouse. By October, 1995, leaf mottle symptoms, similar to those of HLB, were observed in all three grafted trees. In March 1996, one of the A. atalantia plants was transferred to a screenhouse and has been maintained there. The leaf mottle symptoms persisted. DNA was extracted from leaf samples in October 2006 and assayed by nested-PCR using primer set fDl/rD1 in the first round (10 cycles) and primer set OI1/OI2c in the second round (35 cycles) amplification. A ~1.1 kb DNA band was detected in samples from symptomatic leaves but not healthy leaf samples of A. atalantia and C. reticulata. XbaI digestion of the amplicon yielded a ~500 bp and a ~600 bp fragments, characteristic of Ca. L. asiaticus. Similarly, a standard PCR using primer set A5/J2 yielded a ~700 bp DNA band characteristic of Ca. L. asiaticus from symptomatic leaf samples from A. buxifolia and C. reticulata only. This is the first report of graft-transmission and PCR detection of Ca. L. asiaticus from A. buxifolia in Guangdong, P. R. China.