Publications

4504

In a recent publication the name Solimonadaceae Losey et al. 2013 has been proposed as a replacement name for the family name Sinobacteraceae Zhou et al. 2008. This course of action contravenes the current Code governing the nomenclature of prokaryotes, making Solimonadaceae Losey et al. 2013 an illegitimate name that neither has claim to priority nor can be used as a correct name. Closer examination of publications dealing with the taxonomy of members of the genera Solimonas and Sinobacter and the placement of these taxa at the rank of family and order reveal problems associated with the application of the family names Sinobacteraceae Zhou et al. 2008, Nevskiaceae Henrici and Johnson 1935 (Approved Lists 1980) and Lysobacteraceae Christensen and Cook 1978 (Approved Lists 1980) and the order names Lysobacterales Christensen and Cook 1978 (Approved Lists 1980) and Xanthomonadales Saddler and Bradbury 2005.

Huanglongbing, or citrus greening disease, is associated with infection by the phloem-limited bacterium ‘Candidatus Liberibacter asiaticus’. Infection with ‘Ca. L. asiaticus’ is incurable; therefore, knowledge regarding ‘Ca. L. asiaticus’ biology and pathogenesis is essential to develop a treatment. However, ‘Ca. L. asiaticus’ cannot currently be successfully cultured, limiting its study. To gain insight into the conditions conducive for growth of ‘Ca. L. asiaticus’ in vitro, ‘Ca. L. asiaticus’ inoculum obtained from seed of fruit from infected pomelo trees (Citrus maxima ‘Mato Buntan’) was added to different media, and cell viability was monitored for up to 2 months using quantitative polymerase chain reaction in conjunction with ethidium monoazide. Media tested included one-third King's B (K), K with 50% juice from the infected fruit, K with 50% commercially available grapefruit juice, and 100% commercially available grapefruit juice. Results show that juice-containing media dramatically prolong viability compared with K in experiments reproduced during 2 years using different juice sources. Furthermore, biofilm formed at the air–liquid interface of juice cultures contained ‘Ca. L. asiaticus’ cells, though next-generation sequencing indicated that other bacterial genera were predominant. Chemical characterization of the media was conducted to discuss possible factors sustaining ‘Ca. L. asiaticus’ viability in vitro, which will contribute to future development of a culture medium for ‘Ca. L. asiaticus’.

‘Candidatus Phytoplasma australiense’ is associated with a number of plant diseases in New Zealand. The only known vector of this pathogen was Zeoliarus atkinsoni, a planthopper considered to be monophagous on New Zealand flax (Phormium spp.). The work carried out shows that Z. oppositus, which is polyphagous, is able to vector ‘Ca. P. australiense’ to both Coprosma robusta (karamu) and Cordyline australis (New Zealand cabbage tree). Although transmission was achieved to both these species, the disease symptomatology was more evident in C. australis. Two approaches were taken to achieve transmission. First, insects were collected from areas around symptomatic Coprosma plants and caged directly on test plants. Second, insects were collected from grasses and sedges in areas where disease was less evident and were fed on known infected Coprosma plants prior to being caged on test plants. Transmission was achieved using both approaches, although transmission was far greater (30% compared with 4%) from insects that were directly applied. Phytoplasma DNA was detected in 12% of Z. oppositus individuals tested during all the trials. This work identifies a new vector for ‘Ca. P. australiense’ and contributes to our understanding of the ecology of Cordyline sudden decline and Coprosma lethal decline.