Plant Disease

Peony (Paeonia tenuifolia L.) is a herbaceous perennial plant known for its beautiful and showy flowers. In Serbia it is native to the Deliblato Sands and is used as an ornamental and medicinal plant in folk medicine. This plant species has become a rarity and for that reason peony was introduced into a botanical collection near Backi Petrovac (northern Serbia), where it has been maintained since 1988. Reddening of lower leaves observed on 10% of plants (5 of 50) in the collection at flowering in May 2012 gradually progressed throughout affected plants by the seed maturation stage. Five leaves from each of three reddened and three symptomless plants were sampled at the end of July 2012. Total nucleic acid was extracted separately from individual leaves (30 samples) using the CTAB (cetyltrimethylammonium bromide) method (2). A nested PCR assay using universal primer pairs P1/P7, followed by R16F2n/R16R2 (4), amplified 16S rDNA fragments of 1.8 and 1.2 kb, respectively. DNA from all three reddened plants (15 samples) yielded 1.2-kb amplicons after nested PCRs. Restriction fragment length polymorphism (RFLP) patterns obtained by digestion of nested products with endonucleases AluI, TruI, HpaII, or HhaI (Thermo Scientific, Lithuania) (4) were identical to those of the STOL reference strain included for comparative purposes, indicating that symptoms were consistently associated with plant infection by ‘Ca. Phytoplasma solani’ (Stolbur) phytoplasma. The 16S rDNA amplicons from two peony plants (1.2 kb from B15 and 1.8 from B18) were sequenced (GenBank Accession No. KC960487 and KF614623, respectively). BLAST analysis revealed a 100% identity between the sequences and GenBank sequences of Stolbur phytoplasma, subgroup 16SrXII-A phytoplasma, previously detected in maize (JQ730750) in Serbia and red clover (EU814644.1) in the Czech Republic. Phytoplasma associated diseases of other species of the genus Paeonia (P. lactiflora Pall. and P. suffruticosa Andrews) have been described elsewhere. Disease symptoms on P. lactiflora from Chile were associated with the phytoplasma that belongs to the ribosomal subgroup 16SrVII-A (‘Ca. Phytoplasma fraxini’) (1). Also, Stolbur phytoplasma from the 16SrXII group was detected on P. suffruticosa plants in China, manifesting yellowing symptoms (3). To our knowledge, this is the first report of naturally occurring Stolbur phytoplasma disease of P. tenuifolia L. in Serbia. References: (1) N. Arismendi et al. Bull. Insectol. 64:S95, 2011. (2) X. Daire et al. Eur. J. Plant Pathol. 103:507, 1997. (3) Y. Gao et al. J. Phytopathol. 161:197, 2013. (4) I. M. Lee et al. Int. J. Syst. Bacteriol. 48:1153, 1998.

Sweet cherry (Prunus avium L.) is a deciduous tree originating in the Black Sea/Caspian Sea region where Asia and Europe converge. Being highly valued for its timber and fruit, sweet cherry has been cultivated and naturalized on all continents. Over the past decade, the area of sweet cherry cultivation increased rapidly in China and has reached 140,000 ha. In April 2013, sweet cherry trees (cv. Summit) exhibiting floral virescence symptoms were observed in two orchards located in suburban Taian, Shandong Province, China. The diseased trees developed flowers having white petals with green veins or abnormal floral structures having cupped, green petals. The affected flowers failed to set fruit. A month following the first appearance of the virescence symptoms, the diseased trees became wilted and eventually died. Leaf and stem samples were collected from nine symptomatic and two nearby symptomless trees. Total DNA was extracted from each sample using the Plant Quick DNA Extract Kit (TianGen, Beijing, China). Nested-PCR was carried out using phytoplasma-universal primer pairs P1/P7 and R16F2n/R16R2 (1). All PCR assays with DNA templates from symptomatic samples yielded an amplicon of 1.25 kb, corresponding to the full-length F2nR2 region of phytoplasmal 16S rDNA. No amplicon was generated in PCRs containing DNA templates from symptomless plants. The amplicons were cloned into plasmid vector pMD18-T (TaKaRa, Dalian, China) and sequenced. The obtained sequences were nearly identical, and a representative sequence was deposited into GenBank (Accession No. KF268424). An analysis of the sequence through the iPhyClassifier (4) revealed that the sweet cherry virescence (SCV) disease was associated with infection by a phytoplasma closely related to the reference strain of ‘Candidatus Phytoplasma ziziphi.’ The 16S rDNA F2nR2 region of the SCV phytoplasma shared 99.8% nucleotide sequence identity with that of ‘Candidatus Phytoplasma ziziphi’ reference strain (Accession No. AB052876). A computer-simulated restriction fragment length polymorphism (RFLP) analysis of the SCV phytoplasma 16S rDNA F2nR2 sequence with a set 17 restriction enzymes (3) resulted in a collective RFLP profile identical to the reference pattern of the elm yellows phytoplasma group, subgroup B (16SrV-B). Phytoplasmal diseases of sweet cherry were reported previously in Europe and the etiological agents were phytoplasmas of other groups, including the aster yellows group (16SrI), the X-disease group (16SrIII), and the apple proliferation group (16SrX) (2). To our knowledge, this is the first report of a phytoplasmal disease of sweet cherry in China, and the SCV phytoplasma is a new member of the subgroup 16SrV-B. Presence of 16SrV-B phytoplasmas and their etiological association with various plant diseases in China have been reported previously; affected host plants included jujube, hemp fiber, paper mulberry, Chinese cherry, plum, apricot, red barberry, clover, dianthus, elm, and sunshine tree. Our identification of the SCV phytoplasma expands the known plant host range of the 16SrV-B phytoplasma lineage. The impact of the SCV phytoplasma in the regional ecosystem and in sweet cherry production is being assessed. References: (1) I. M. Lee et al. Int. J. Syst. Bacteriol. 48:1153, 1998. (2) S. Paltrinieri et al. Acta Hort. 550:365, 2001. (3) W. Wei et al. Int. J. Syst. Evol. Microbiol. 57:1855, 2007. (4) Y. Zhao et al. Int. J. Syst. Evol. Microbiol. 59:2582, 2009.

In April and May of 2012, bell pepper (Capsicum annuum) plants exhibiting symptoms that resembled those of the bacterium ‘Candidatus Liberibacter solanacearum’ infection (2,4) were observed in commercial pepper fields in several departments in Honduras, including Francisco Morazán, Ocotepeque, El Paraíso, and Olancho. Many of the fields were infested with the psyllid Bactericera cockerelli, a vector of ‘Ca. L. solanacearum’ (3). The plants exhibited chlorotic or pale green apical growth and leaf cupping, sharp tapering of the leaf apex, shortened internodes, and overall stunting (2,4). All cultivars grown were affected and 20 to 75% of plants in each field were symptomatic. Pepper (var. Nataly) plant samples were collected from a total of eight affected fields (two fields per department). Total DNA was extracted from the top whole leaf tissue of a total of 19 plants, including 14 symptomatic and 5 asymptomatic pepper plants, with the cetyltrimethylammonium bromide (CTAB) buffer extraction method (1). The DNA samples were then tested by PCR using specific primer sets OA2/OI2c and OMB 1482f/2086r to amplify a portion of 16S rDNA and the outer membrane protein (OMB) genes, respectively, of ‘Ca. L. solanacearum’ (1,2). OMB gene and 16S rDNA fragments of 605 and 1,168 bp, respectively, were amplified from the DNA of 7 of 14 (50%) symptomatic plants with each primer set, indicating the presence of ‘Ca. L. solanacearum.’ No ‘Ca. L. solanacearum’ was detected in the five asymptomatic plants with either primer sets. DNA amplicons with both primer sets were cloned from the DNA of plant samples collected from each of the three departments: Francisco Morazán (in the locality of Zamorano), Ocotepeque (municipality of Plan del Rancho in Sinuapa), and El Paraíso (municipality of Danlí), and four clones of each of the six amplicons were sequenced. BLASTn analysis of the 16S rDNA resulted in a single consensus sequence for all three locations (deposited in GenBank as Accession Nos. KF188226, KF188227, and KF188228) and showed 100% identity to numerous 16S rDNA sequences of ‘Ca. L. solanacearum’ in GenBank, including accessions HM245242, JF811596, and KC768319. Similarly, identical OMB consensus sequences were observed in all three locations (deposited in GenBank as KF188230, KF188231, and KF188233) that are 100% identical to several ‘Ca. L. solanacearum’ sequences in GenBank (e.g., KC768331 and CP002371) along with a second consensus sequence (deposited in GenBank as accession KF188232) from Ocotepeque that was 99% identical to the consensus sequence from the three locations and sequences in GenBank. To our knowledge, this is the first report of ‘Ca. L. solanacearum’ associated with pepper crops in Honduras, where pepper constitutes an economically important commodity. This bacterium has also caused millions of dollars in losses to potato and several other solanaceous crops in United States, Mexico, Central America, and New Zealand (1,2,3,4). Furthermore, ‘Ca. L. solanacearum’ has been reported to severely damage carrot crops in Europe, where it is transmitted to carrot by the psyllids Trioza apicalis and Bactericera trigonica (3). Monitoring this pathogen and its vectors will prevent serious damage they cause to economically important crops. References: (1) J. M. Crosslin. Southwest. Entomol. 36:125, 2011. (2) L. W. Liefting et al. Plant Dis. 93:208, 2009. (3) J. E. Munyaneza. Am. J. Pot. Res. 89:329, 2012. (4) J. E. Munyaneza et al. Plant Dis. 93:1076, 2009.

‘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.

Elm yellows (EY) is a lethal disease of American (Ulmus americana L.) and other elm species (1). On the Pennsylvania State University campus, EY, together with Dutch elm disease, has killed 82 of about 400 mature elms since 2007, the year of first EY detection. Candidatus Phytoplasma ulmi, associated with EY, has been reported to be transmitted by the whitebanded elm leafhopper Scaphoideus luteolus Van Duzee, the meadow spittlebug Philaenus spumarius L., and the leafhopper Allygus atomarius Fabricius (1) in North America, but correlation of these insects with EY in the eastern United States has not been reported. Three Cicadellidae collections using sweep nets and aspirators were performed from July to September 2012 on branches of an EY infected red elm (U. rubra Muh; 40°48.408′N, 77°52.208′W) and on vegetation within a 0.5 km radius. The red elm is in close proximity to trees, shrubs, and a managed meadow and has repeatedly tested positive for EY since 2007. During each collection, about 200 cicadellids were captured in BioQuip No-See-Um catch bags with cups, and the bags were hung around the red elm branches, forcing the insects to feed on the infected tree for 24 h. Insects were transferred to BugDorm rearing tents containing wild grasses, elm seedlings, cowpeas, celery, carrots, and basil, all grown from seed, and were kept for 3 weeks in a controlled environment chamber at 28°C and 70% humidity with a 16-h photoperiod. Insects easily recognized in the same species or individual insects of uncertain identity were then isolated for about 1 week in cages each containing one 6-month-old healthy American elm seedling (grown from seed in growth chamber). Up to 10 morphospecies were found in each collection, with 1 to 20 individuals per morphospecies. The total number of unique morphospecies used in the three transmission trials and later identified as different species was 8. Dead insects collected daily were stored in 80% ethanol and later identified to genus or species level. About 70% insect mortality was recorded, but about 60 individuals from each collection survived the change of diet and environment. After 3 months, individual elm seedlings were tested by RT-PCR (3) for the presence of phytoplasmas using universal primers fU5/rU3 (2). PCR products were visualized on 1.5% agarose gel, and if DNA was amplified, it was cloned and sequenced. Three of 30 seedlings tested positive for phytoplasmas and sequencing of the cloned products (24 clones were sequenced per transformation, per each of the three positive seedlings) confirmed that only Ca. P. ulmi was present in the 3 infected seedlings but not in the remaining 27 or in 46 unexposed control seedlings. The 3 seedlings were each exposed to a single insect and the same insects that were used in the transmission trial were identified. One spittlebug (Cercopidae) Lepyronia quadrangularis Say, one P. spumarius, and one leafhopper in the genus Latalus (Cicadellidae: Deltocephalinae) were identified as vectors. The phytoplasma-positive seedlings showed stunting and yellowing, and died shortly after testing. Other insects captured and identified in the survey were A. atomarius, Neophilaenus lineatus L., Metcalfa pruinosa Say, Amblysellus curtisii Fitch and individuals in the genera Draeculacephala, Elymana, Empoasca, Mesamia, Stroggylocephalus, and Ceratagallia. S. luteolus was not captured during this sampling but was captured on yellow sticky traps and in light traps in previous years at other locations on the campus. This is the first report suggesting that L. quadrangularis and Latalus sp. can serve as natural vectors of EY. References: (1) P. Herath et al. Plant Dis. 94:1355, 2010. (2) H. Lorenz et al. Phytopathology 85:771, 1995. (3) P. Margaria et al. Plant Dis. 91:1496, 2007.

‘Candidatus Liberibacter asiaticus’ is the most prevalent Liberibacter sp. associated with huanglongbing (HLB) in Brazil. Within São Paulo state (SP), HLB has spread more rapidly to and reached higher incidence in regions with relatively mild (cooler) summer temperatures. This suggests that climate can influence disease spread and severity. ‘Ca. L. asiaticus’ titers on soft, immature leaves from infected ‘Valencia’ sweet orange plants exposed to different temperature regimes and adult Diaphorina citri fed for 48 h on these plants for ‘Ca. L. asiaticus’ acquisition were determined by quantitative polymerase chain reaction in two experiments. The first experiment included plants with three levels of infection, three incubation periods (IPs), and air temperatures favorable (14.6 to 28°C) and unfavorable (24 to 38°C) to ‘Ca. L. asiaticus’. The second included plants with severe late-stage infections, 10 IPs (based on 3-day intervals over 27 days), and three air temperature regimes (12 to 24, 18 to 30, and 24 to 38°C). Overall, ‘Ca. L. asiaticus’ titers and the percentages of ‘Ca. L. asiaticus’-positive psyllids were lower in plants maintained at the warmer temperature regime (24 to 38°C) than in plants maintained in the cooler regimes. The results suggest that the lower incidence and slower spread of ‘Ca. L. asiaticus’ to warmer regions of SP are related to the influence of ambient temperatures on titers of ‘Ca. L. asiaticus’ in leaves.

In May of 2012, eggplant (Solanum melongena) plants in an experimental research plot located at Zamorano in the Department of Francisco Morazán, Honduras, were observed with symptoms that included leaf chlorosis and cupping, overall stunting, and production of small and malformed fruits. The research plot was planted next to a commercial tomato field heavily infested with the psyllid Bactericera cockerelli, a vector of ‘Candidatus Liberibacter solanacearum’ (1,2,3). This bacterium severely affects potato and other solanaceous species and is the putative causal agent of zebra chip disease (2,3). The plot was planted with the eggplant variety ‘China’ and about 25% of the plants were symptomatic. A total of 10 eggplant samples, including five symptomatic and five asymptomatic plants, were collected from the plot. Total DNA was extracted from the leaf tissue of each of the collected plants with the cetyltrimethylammonium bromide (CTAB) buffer extraction method (1). The DNA samples were then tested by PCR using specific primer sets OA2/OI2c and OMB 1482f/2086r to amplify a portion of 16S rDNA and the outer membrane protein (OMB) genes, respectively, of ‘Ca. L. solanacearum’ (1,2). OMB gene and 16S rDNA fragments of 605 and 1,168 bp, respectively, were amplified from the DNA of two of the five (40%) symptomatic plants with each primer set, indicating the presence of ‘Ca. L. solanacearum.’ No ‘Ca. L. solanacearum’ was detected in the five asymptomatic plants with either primer sets. DNA amplicons with both primer sets were cloned from the DNA of the two ‘Ca. L. solanacearum’-positive plant samples and four clones of each of the four amplicons were sequenced. BLASTn analysis of the 16S rDNA resulted in two independent but related consensus sequences (deposited in GenBank as Accession Nos. KF188224 and KF188225) and were 99% similar to each other. The two sequences showed 99 to 100% identity to a number of 16S rDNA sequences of ‘Ca. L. solanacearum’ in Genbank, including accessions HM245242, FJ811596, and KC768319. For the OMB amplicons, a single consensus sequence was obtained following clone sequencing and was deposited in GenBank as accession KF188229. BLASTn analysis of the sequence indicated that it was 100% identical to several OMB sequences of ‘Ca. L. solanacearum’ in GenBank, including accessions KC768331 and CP002371. To our knowledge, this is the first report of ‘Ca. L. solanacearum’ associated with eggplant in Honduras. Eggplant is an economically important commodity in Central America and serious damage to this crop due to this plant pathogen could expand throughout the region, especially if its insect vector B. cockerelli is not properly managed. ‘Ca. L. solanacearum’ has also caused millions of dollars in losses to potato and several other solanaceous crops in the United States, Mexico, Central America, and New Zealand (2,3). In addition, this bacterium severely damages carrot crops in Europe, where it is transmitted to carrot by the psyllids Trioza apicalis and B. trigonica (3,4). It is imperative that both ‘Ca. L. solanacearum’ and its insect vectors be effectively monitored and managed to minimize their threat to economically important vegetable crops in many parts of the world. References: (1) J. M. Crosslin et al. Southwest. Entomol. 36:125, 2011. (2) L. W. Liefting et al. Plant Dis. 93:208, 2009. (3) J. E. Munyaneza. Am. J. Pot. Res. 89:329, 2012. (4) J. E. Munyaneza et al. J. Econ. Entomol. 103:1060, 2010.

During a survey carried out in Jordanian vineyards in August and October 2012, grapevine (Vitis vinifera L.) plants showing typical grapevine yellows (GY) disease symptoms, including leaf discoloration and curling, berry shriveling, and irregular maturation of wood, were observed. In the same vineyards, bindweed (Convolvulus arvensis L.) plants showing stunting and leaf chromatic alteration were found, suggesting the involvement of phytoplasmas in the disease etiology. Using a CTAB method, total DNA was extracted from leaf veins of 25 symptomatic and two asymptomatic grapevines, and from five symptomatic and two asymptomatic bindweeds for PCR analysis. DNAs from periwinkle (Catharanthus roseus (L.) G. Don) plants infected by ‘Ca. Phytoplasma asteris’ strain SAY (group 16SrI), ‘Ca. Phytoplasma solani’ strain STOL (group 16SrXII), and ‘Ca. Phytoplasma ulmi’ strain EY1 (group 16SrV), were used as positive controls. DNAs from healthy periwinkle and reactions without template DNA were employed as negative controls. 16S rDNA nested PCRs, carried out using the primer pairs P1/P7, followed by R16F2n/R16R2 (1), yielded an amplicon of the expected size (1,250-bp) in three grapevine and in five bindweed samples, and in positive controls. Amplicons were not produced with DNA from 22 symptomatic grapevines (probably because samples were collected late in the growing season and phytoplasma distribution in plants was non-uniform [2]); nor from asymptomatic plants and negative controls. PCR products were sequenced by commercial services in Italy (Primm, Milan) and Korea (Macrogen Inc., Soul). Representative 16S rDNA nucleotide sequences were deposited in NCBI GenBank with accessions KC835139 (from grapevine) and KC835140 (from bindweed). The 16S rDNA nucleotide sequences of phytoplasmas identified in grapevine and bindweed in Jordan shared >99.5% sequence identity with ‘Ca. Phytoplasma solani’ reference strain STOL (AF248959), and carried identical STOL-unique signature sequences and distinguishing sequence blocks (3). Phylogenetic and in silico RFLP analyses confirmed the affiliation of phytoplasma strains identified in grapevine and bindweed in Jordan to the species ‘Ca. Phytoplasma solani’ (subgroup 16SrXII-A), opening an avenue to future studies on the dissemination and impact of Bois noir (BN) in Jordan. These studies may add new information about BN, previously reported in neighboring countries (4). Further studies will investigate the role of Hyalesthes obsoletus Signoret, a polyphagous Cixiidae responsible for the BN phytoplasma transmission in Europe, and other possible insect vector(s) in the BN spread in Jordan. References: (1) I.-M. Lee et al. Int. J. Syst. Bact. 48:1153, 1998. (2) F. E. Constable et al. Plant Pathol. 52:267, 2003. (3) F. Quaglino et al. Int. J. Syst. Evol. Microb. 63:2879. (4) E. Choueiri et al. Plant Dis. 86:697, 2002.

The foxtail palm (Wodyetia bifurcata), an Australian native species, is an adaptable and fast-growing landscape tree. The foxtail palm is most commonly used in landscaping in Malaysia. Coconut yellow decline (CYD) is the major disease of coconut associated with 16SrXIV phytoplasma group in Malaysia (1). Symptoms consistent with CYD, such as severe chlorosis, stunting, general decline, and death were observed in foxtail palms from the state of Selangor in Malaysia, indicating putative phytoplasma infection. Symptomatic trees loses their green and vivid appearance as a decorative and landscape ornament. To determine the presence of phytoplasma, samples were collected from the fronds of 12 symptomatic and four asymptomatic palms in September 2012, and total DNA was extracted using the CTAB method (3). Phytoplasma DNA was detected in eight symptomatic palms using nested PCR with universal phytoplasma 16S rDNA primer pairs, P1/P7 followed by R16F2n/R16R2 (2). Amplicons (1.2 kb in length) were generated from symptomatic foxtail palms but not from symptomless plants. Phytoplasma 16S rDNAs were cloned using a TOPO TA cloning kit (Invitrogen). Several white colonies from rDNA PCR products amplified from one sample with R16F2n/R16R2 were sequenced. Phytoplasma 16S rDNA gene sequences from single symptomatic foxtail palms showed 99% homology with a phytoplasma that causes Bermuda grass white leaf (AF248961) and coconut yellow decline (EU636906), which are both members of the 16SrXIV ‘Candidatus Phytoplasma cynodontis’ group. The sequences also showed 99% sequence identity with the onion yellows phytoplasma, OY-M strain, (NR074811), from the ‘Candidatus Phytoplasma asteris’ 16SrI-B subgroup. Sequences were deposited in the NCBI GenBank database (Accession Nos. KC751560 and KC751561). Restriction fragment length polymorphism (RFLP) analysis was done on nested PCR products produced with the primer pair R16F2n/R16R2. Amplified products were digested separately with AluI, HhaI, RsaI, and EcoRI restriction enzymes based on manufacturer's specifications. RFLP analysis of 16S rRNA gene sequences from symptomatic plants revealed two distinct profiles belonging to groups 16SrXIV and 16SrI with majority of the 16SrXIV group. RFLP results independently corroborated the findings from DNA sequencing. Additional virtual patterns were obtained by iPhyclassifier software (4). Actual and virtual patterns yielded identical profiles, similar to the reference patterns for the 16SrXIV-A and 16SrI-B subgroups. Both the sequence and RFLP results indicated that symptoms in infected foxtail palms were associated with two distinct phytoplasma species in Malaysia. These phytoplasmas, which are members of two different taxonomic groups, were found in symptomatic palms. Our results revealed that popular evergreen foxtail palms are susceptible to and severely affected by phytoplasma. To our knowledge, this is the first report of a mixed infection of a single host, Wodyetia bifurcata, by two different phytoplasma species, Candidatus Phytoplasma cynodontis and Candidatus Phytoplasma asteris, in Malaysia. References: (1) N. Nejat et al. Plant Pathol. 58:1152, 2009. (2) N. Nejat et al. Plant Pathol. J. 9:101, 2010. (3) Y. P. Zhang et al. J. Virol. Meth. 71:45, 1998. (4) Y. Zhao et al. Int. J. Syst. Evol. Microbiol. 59:2582, 2009.

In this study, two polyclonal antibodies were produced against the Omp protein of ‘Candidatus Liberibacter asiaticus’. First, omp genes were sequenced to exhibit 99.9% identity among 137 isolates collected from different geographical origins. Then, two peptides containing the hydrophobic polypeptide-transport-associated (POTRA) domain and β-barrel domain, respectively, were identified on Omp protein. After that, these two peptides were overexpressed in Escherichia coli and purified by affinity chromatography to immunize the white rabbits. Finally, the antiserum was purified by affinity chromatography. The two Omp antibodies gave positive results (0.454 to 0.633, 1:1,600 dilution) in enzyme-linked immunosorbent assay against ‘Ca. L. asiaticus’-infected samples collected from different geographical origins but revealed negative results against other pathogen-infected, nutrient-deficient and healthy samples. The antibody against the POTRA domain of Omp protein could detect ‘Ca. L. asiaticus’ in 45.7% of the symptomatic samples compared with a 56.2% detection rate with a polymerase chain reaction assay. These new antibodies will provide a very useful supplement to the current approaches to ‘Ca. L. asiaticus’ detection and also provide powerful research tools for tracking distribution of this pathogen in vivo.