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Atalantia buxifolia (Poir.) Oliv., synonym Severinia buxifolia (Poir.) Ten. as commonly found in literature, is a common landscape plant and a popular Chinese medicinal herb known as Jiubingle or Dongfengjie. It remains unclear if this rutaceous plant could host ‘Candidatus Liberibacter asiaticus’, the pathogen of citrus Huanglongbing (HLB) in Guangdong, P. R. China. This information is important for HLB control in citrus because infected A. buxifolia could serve as a source of inoculum. In August of 1994, three A. buxifolia plants adjacent to a citrus experimental orchard of the South China Agricultural University at Guangzhou were found showing leaf mottle/yellowing symptoms. Two buds from each plant were grafted onto three mandarin trees (Citrus reticulata cv. Pongan) in a psyllid-proof screenhouse for indexing. By October of 1995, typical leaf mottle symptoms were observed in all three grafted trees compared with a healthy control. In March of 1996, one of the A. buxifolia plants was transferred to a screenhouse and has been maintained there. The leaf mottle/yellowing symptoms persisted but did not significantly affect plant growth. DNA was extracted from leaf samples in October 2006 by using the CTAB (cetyltrimethylammoniumbromide) method and assayed by nested-PCR using the general bacterial 16S rDNA primer set fDl/rD1 as the first round of amplification and primer set OI1/OI2c as second round amplification (1,3). After agarose gel electrophoresis and staining with ethidium bromide, an approximate 1.1-kb DNA band was detected in symptomatic samples but not healthy leaf samples of A. buxifolia and C. reticulata. XbaI digestion of the amplicons yielded approximate 500- and 600-bp fragments, characteristic of ‘Ca. L. asiaticus’. Similarly, a standard PCR with primer set A5/J2 (3) yielded an approximate 700-bp DNA band characteristic of ‘Ca. L. asiaticus’ from symptomatic samples only. To our knowledge, this is the first report of graft transmission and PCR detection of ‘Ca. L. asiaticus’ from A. buxifolia in Guangdong, P. R. China. This work also confirms the findings from Taiwan (2) that A. buxifolia could serve as a source of ‘Ca. L. asiaticus’. References: (1) X. Deng et al. Online publication. doi:10.1094/PHP-2007-0419-01-BR. Plant Health Progress, 2007. (2) T.-H. Hung et al. Eur. J. Plant Pathol. 107:183, 2001. (3) S. Jagoueix et al. Mol. Cell. Probes 10:43, 1996.

Little is known about ‘Candidatus Liberibacter americanus’, a causal agent of huanglongbing or greening disease in Brazil, or its interaction with citrus trees. Greenhouse experiments were conducted with the objective of determining conditions favorable for transmission from field affected trees to young potted plants, to evaluate the reaction of multiple citrus species to the disease, and to determine the efficiency of pathogen propagation from individual buds. Single buds or bark pieces of various sizes or bark plus wood (budstick) that were removed from symptomatic or asymptomatic branches were used as sources of inoculum. Transmission success was evaluated through polymerase chain reaction analysis of total DNA extracted from leaf samples. Beginning at 4 to 5 months after inoculation, infected plants manifested leaf mottling and symptoms similar to those of iron, manganese, and zinc deficiencies. Blotchy mottled leaves appeared only on sweet oranges and Murcott tangor. Pathogen transmission was higher for these citrus cultivars and species (31.2 to 65.2%) than for limes, mandarins, or Swingle citrumelo (2.0 to 25.0%). Deformed small fruits with brownish columellae also developed on sweet oranges. Only buds and budsticks served as sources of inoculum and the larger the piece of tissue, the higher the transmission efficiency. Experiments initiated during the winter showed lower rates of graft tissue survival but relatively higher percentages of pathogen transmission.

Summary The phylum Chlamydiae contains obligate intracellular bacteria, several of which cause disease in their hosts. Morphological studies have suggested that this group of bacteria may be pathogens of fish, causing cysts in epithelial tissue – epitheliocystis. Recently, the first genetic evidence of a chlamydial aetiology of this disease in seawater reared Atlantic salmon from Norway and Ireland was presented, and the agent was given the name ‘ Candidatus Piscichlamydia salmonis’. In this article we present molecular evidence for the existence of a novel Chlamydiae that also may cause epitheliocystis in Norwegian salmonids. This novel Chlamydiae has been found in salmonid fish from freshwater, and based on its partial 16S rRNA gene, it may constitute a third genus in the family Chlamydiaceae , or a closely related sister family. By using whole‐mount RNA–RNA hybridization we demonstrate how infected cells are distributed in a patchy manner on a gill arch. The morphology of the novel Chlamydiae includes the characteristic head‐and‐tail cells that have been described earlier from salmonid fish suffering from epitheliocystis. We propose the name ‘ Candidatus Clavochlamydia salmonicola’ for this agent of epitheliocystis in freshwater salmonids.