Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/1/2008
Publication Date: 6/1/2008
Citation: Duan, Y., Zhou, L., Gottwald, T.R., Gabriel, D. 2008. First Report of Dodder Transmission of Candidatus Liberibacter asiaticus to Tomato (Lycopersicon esculentum). Plant Disease. 92:831. Interpretive Summary:
Technical Abstract: Huanglongbing (HLB) or “greening”, caused by the fastidious a-proteobacteria Candidatus Liberibacter asiaticus (Las), Ca. L. americanus (Lam) and Ca. L. africanus, is one of the most devastating diseases of citrus worldwide (1). Las was first detected in South Florida in 2005, and has spread throughout the citrus growing areas of Florida. Las is transmitted naturally by the Asian citrus psyllid, Diaphorina citri, and can also be transmitted by graft propagation and via various species of dodder (Cuscuta). HLB affects most if not all citrus and citrus relatives within family Rutaceae (2), including the ornamental shrub Murraya paniculata (3). In addition, Las and Lam can infect tobacco (Nicotiana xanthi) and periwinkle (Catharanthus roseus) (1, 4). Here we report that Las can infect tomato (Lycopersicon esculentum) variety Manapal and FL47. Manapal and FL 47 plants grown from seed were placed adjacent to Las-infected sweet orange (Citrus sinensis) plants with dodder (Cuscuta pentagona) already well established on them. Young dodder shoots still connected to the citrus were draped over the tomato plants and subsequently became attached to the tomato stems. After one month, the tomato plants were detached from the citrus and most of the dodder removed. One month later, these tomato plants started to show vein clearing, and then the mature leaves became thicker and leathery. Some leaves showed blotchy mottle symptoms and some fruits became lopsided, in a manner similar to HLB symptom expression on citrus. PCR amplification of the Las 16S rDNA using primers OI1/OI2c (3) and the ß-operon using primers A2/J5 (5), followed by DNA sequencing of the cloned amplicons, confirmed the presence of Las in symptomatic tomato tissues. However, the PCR amplicon from tomato cv. Manapal and FL47 appeared to be weak by comparison with those from citrus or periwinkle, indicating that Las bacteria multiply at a lower titer in these tomato varieties.