Publications

4774

ABSTRACT Herein we present the draft genome sequence and annotation of “Candidatus Rickettsia asemboensis” strain NMRCii. “ Ca. Rickettsia asemboensis” is phylogenetically related to but distinct from the flea-borne spotted fever pathogen Rickettsia felis . “ Ca. Rickettsia asemboensis” was initially identified in and subsequently isolated from Ctenocephalides cat and dog fleas from Kenya.

ABSTRACT “Candidatus Methylacidiphilum kamchatkense” strain Kam1 is an aerobic methane-oxidizing thermoacidophilic bacterium belonging to the Verrucomicrobia phylum. It was recovered from an acidic geothermal site in Uzon Caldera, Kamchatka, Russian Federation. Its genome possesses three complete pmoCAB gene clusters encoding particulate methane monooxygenase enzymes and a complete Calvin-Benson-Bassham cycle for carbon assimilation.

ABSTRACT Here, we report the draft genome sequence of “Candidatus Liberibacter asiaticus” strain FL17, isolated from a huanglongbing (HLB)-affected citrus tree in central Florida. The FL17 genome comprised 1,227,253 bp, with a G+C content of 36.5%, 1,175 predicted open reading frames, and 53 RNA genes.

Huanglongbing (HLB), caused by the bacterium ‘Candidatus Liberibacter’ spp., is currently one of the most serious diseases of citrus plants and has caused substantial economic losses. Thus far, there is no source of genetic resistance to HLB in the genus Citrus or its relatives. However, several studies have reported Poncirus trifoliata and some of its hybrids to be more tolerant to the disease. The main objective of this study was to report differences in the incidence of ‘Ca. L. asiaticus’ infection in citrandarin plants, hybrids from Sunki mandarin (Citrus sunki (Hayata) hort. ex Tanaka), and trifoliate orange Rubidoux (P. trifoliata (L.) Raf.)), after conducting an extensive survey under field conditions. These hybrid plants were established for approximately 7 years in an area with a high incidence of ‘Ca. L. asiaticus’-infected plants. We selected two experimental areas (area A and area B), located approximately 10 m apart. Area A consists of Pera sweet orange (C. sinensis (L.) Osb.) grafted onto 56 different citrandarin rootstocks. Area B consists of citrandarin scions grafted onto Rangpur lime (C. limonia Osb.) rootstock. Bacteria in the leaves and roots were detected using real-time quantitative polymerase chain reaction. The incidence of ‘Ca. L. asiaticus’-infected plants was 92% in area A and 14% in area B. Because infected plants occurred in both areas, we examined whether the P. trifoliata hybrid rootstock influenced HLB development and also determined the distribution of ‘Ca. L. asiaticus’ in Citrus tree tissues. Although this survey does not present evidence regarding the resistance of P. trifoliata and its hybrids in relation to bacteria or psyllids, future investigation, mainly using the most promising hybrids for response to ‘Ca. L. asiaticus’, will help us to understand the probable mechanism of defense or identifying compounds in P. trifoliata and its hybrids that are very important as strategy to combat HLB. Details of these results are presented and discussed in this article.