GA 1565-2-4 BWT, GA 219-1-2 BWT, GA 1095-1-4 BWT, and GA 1405-1-2 BWT Bacterial Wilt-tolerant Tomato

Bacterial wilt, caused by the soil-borne pathogen Pseudomonas solanacearum E. F. Sm., causes major economic losses in tomato (Lycopersicon esculentum Mill.) production in many warm, humid regions of the world (6, 8). Selections of L. esculentum (GA 1565-2-4 BWT, GA 219-1-2 BWT and GA 1095-1-4 BWT) and of L. esculentum x L. pimpinellifolium (Jusl.) Mill. (GA 1405- 1-2 BWT), all possessing high tolerance levels to P. solanacearum, are jointly released by the ARS/USDA and the Univ. of Georgia

Pan-Genome of Novel Pantoea stewartii subsp. indologenes Reveals Genes Involved in Onion Pathogenicity and Evidence of Lateral Gene Transfer

Pantoea stewartii subsp. indologenes (Psi) is a causative agent of leafspot on foxtail millet and pearl millet; however, novel strains were recently identified that are pathogenic on onions. Our recent host range evaluation study identified two pathovars; P. stewartii subsp. indologenes pv. cepacicola pv. nov. and P. stewartii subsp. indologenes pv. setariae pv. nov. that are pathogenic on onions and millets or on millets only, respectively. In the current study, we developed a pan-genome using the whole genome sequencing of newly identified/classified Psi strains from both pathovars [pv. cepacicola (n = 4) and pv. setariae (n = 13)]. The full spectrum of the pan-genome contained 7030 genes. Among these, 3546 (present in genomes of all 17 strains) were the core genes that were a subset of 3682 soft-core genes (present in ≥16 strains). The accessory genome included 1308 shell genes and 2040 cloud genes (present in ≤2 strains). The pan-genome showed a clear linear progression with &gt;6000 genes, suggesting that the pan-genome of Psi is open. Comparative phylogenetic analysis showed differences in phylogenetic clustering of Pantoea spp. using PAVs/wgMLST approach in comparison with core genome SNPs-based phylogeny. Further, we conducted a horizontal gene transfer (HGT) study using Psi strains from both pathovars along with strains from other Pantoea species, namely, P. stewartii subsp. stewartii LMG 2715T, P. ananatis LMG 2665T, P. agglomerans LMG L15, and P. allii LMG 24248T. A total of 317 HGT events among four Pantoea species were identified with most gene transfer events occurring between Psi pv. cepacicola and Psi pv. setariae. Pan-GWAS analysis predicted a total of 154 genes, including seven gene-clusters, which were associated with the pathogenicity phenotype (necrosis on seedling) on onions. One of the gene-clusters contained 11 genes with known functions and was found to be chromosomally located.</jats:p

Pan-Genome of Novel Pantoea stewartii subsp. indologenes Reveals Genes Involved in Onion Pathogenicity and Evidence of Lateral Gene Transfer

Pantoea stewartii subsp. indologenes (Psi) is a causative agent of leafspot on foxtail millet and pearl millet; however, novel strains were recently identified that are pathogenic on onions. Our recent host range evaluation study identified two pathovars; P. stewartii subsp. indologenes pv. cepacicola pv. nov. and P. stewartii subsp. indologenes pv. setariae pv. nov. that are pathogenic on onions and millets or on millets only, respectively. In the current study, we developed a pan-genome using the whole genome sequencing of newly identified/classified Psi strains from both pathovars [pv. cepacicola (n = 4) and pv. setariae (n = 13)]. The full spectrum of the pan-genome contained 7030 genes. Among these, 3546 (present in genomes of all 17 strains) were the core genes that were a subset of 3682 soft-core genes (present in ≥16 strains). The accessory genome included 1308 shell genes and 2040 cloud genes (present in ≤2 strains). The pan-genome showed a clear linear progression with &gt;6000 genes, suggesting that the pan-genome of Psi is open. Comparative phylogenetic analysis showed differences in phylogenetic clustering of Pantoea spp. using PAVs/wgMLST approach in comparison with core genome SNPs-based phylogeny. Further, we conducted a horizontal gene transfer (HGT) study using Psi strains from both pathovars along with strains from other Pantoea species, namely, P. stewartii subsp. stewartii LMG 2715T, P. ananatis LMG 2665T, P. agglomerans LMG L15, and P. allii LMG 24248T. A total of 317 HGT events among four Pantoea species were identified with most gene transfer events occurring between Psi pv. cepacicola and Psi pv. setariae. Pan-GWAS analysis predicted a total of 154 genes, including seven gene-clusters, which were associated with the pathogenicity phenotype (necrosis on seedling) on onions. One of the gene-clusters contained 11 genes with known functions and was found to be chromosomally located

Pan-genome of Novel &lt;em&gt;Pantoea stewartii&lt;/em&gt; subsp. &lt;em&gt;indologenes&lt;/em&gt; Reveal Genes Involved in Onion Pathogenicity and Evidence of Lateral Gene Transfer

Pantoea stewartii subsp. indologenes (Psi) is a causative agent of leafspot of foxtail millet and pearl millet; however, novel strains were recently identified that are pathogenic on onion. Our recent host range evaluation study identified two pathovars; P. stewartii subsp. indologenes pv. cepacicola pv. nov. and P. stewartii subsp. indologenes pv. setariae pv. nov. that are pathogenic on onion and millets or on millets only, respectively. In the current study we developed a pan-genome using the whole genome sequencing of newly identified/classified Psi strains from both pathovars [pv. cepacicola (n= 4) and pv. setariae (n=13)]. The full spectrum of the pan-genome contained 7,030 genes. Among these, 3,546 (present in genomes of all 17 strains) were the core genes that were a subset of 3,682 soft-core genes (present in &amp;ge;16 strains). The accessory genome included 1,308 shell genes and 2,040 cloud genes (present in &amp;le; 2 strains). The pan-genome showed a clear liner progression with &amp;gt;6,000 genes, suggesting the pan-genome of Psi is open. Comparative phylogenetic analysis showed differences in phylogenetic clustering of Pantoea spp. using PAVs/wgMLST approach in comparison to core genome SNP-based phylogeny. Further, we conducted a horizontal gene transfer (HGT) study including four other Pantoea species namely, P. stewartii subsp. stewartii LMG 2715T, P. ananatis LMG 2665T, P. agglomerans LMG L15, and P. allii LMG 24248T. A total of 317 HGT events among four Pantoea species were identified with most gene transfers observed between Psi pv. cepacicola and Psi pv. setariae. Pan-GWAS analysis predicted a total of 154 genes including seven cluster of genes associated with the pathogenicity phenotype on onion. One of the clusters contain 11 genes with known functions and are found to be chromosomally located.</jats:p

Epiphytic Survival of <i>Pantoea ananatis</i> on <i>Richardia scabra</i> L. in Georgia

Pantoea ananatis, the causal organism of center rot of onion (Allium cepa L.), can survive on different weeds but, in a previous survey, it was most commonly found on Florida pusley (Richardia scabra L.). The epiphytic survival of P. ananatis on R. scabra under different temperature and moisture regimes was investigated. Weed seedlings were spray inoculated with rifampicin-resistant strain PNA 97-1rif at either 103 or 108 CFU/ml and incubated in a growth chamber at 15.5 or 21.1°C at 65% relative humidity for 96 h postinoculation (hpi), which represented the mean environmental conditions during mid-March to mid-May in Vidalia, GA when onion production and R. scabra presence overlap. For plants inoculated with P. ananatis at 103 CFU/ml, the bacterium survived for 96 hpi when incubated at 21.1°C, with mean populations of 1.7 × 102 CFU/g of leaf tissue. In contrast, no viable bacteria were detected after 72 hpi at 15.5°C. For plants inoculated with P. ananatis at 108 CFU/ml, the bacterium survived for 96 hpi at 21.1°C (3.8 × 105 CFU/g) whereas, during the sample time period, viable bacterial populations were not detected at 15.5°C. Survival of P. ananatis on R. scabra was also monitored during alternating 12 h wet and 12 h dry periods, or continuous wet or dry periods for 96 hpi at 15.5 or 21.1°C. Compared with initial or continuous dry periods, P. ananatis survived significantly better with a 12 h wet/12 h dry cycle or a continuous 96 hpi wet period at both 15.5 and 21.1°C. Unlike at 15.5°C, P. ananatis populations (7.4 × 102 CFU/g) survived for 96 hpi at 21.1°C under a cycle of 12 h dry and 12 h wet. These results demonstrate that P. ananatis can survive on R. scabra leaves under conditions of 21.1°C and prolonged leaf wetness and may potentially serve as a source of inoculum to onion. </jats:p

Pseudomonas coronafaciens sp. nov., a new phytobacterial species diverse from Pseudomonas syringae

We propose Pseudomonas coronafaciens sp. nov. as a new species in genus Pseudomonas, which is diverse from P. syringae. We also classified strains from onions which are responsible for yellow bud (YB) disease as P. coronafaciens. Sequencing of 16S rRNA gene and multi-locus sequence analysis (MLSA) of housekeeping genes (gyrB, rpoD, gltA and gap1 genes) for the P. syringae pv. coronafaciens strains along with other strains of P. syringae pathovars resulted in a distinct cluster separate from other P. syringae pathovars. Based on DNA-DNA relatedness, pathotype strain of P. syringae pv. coronafaciens (CFBP 2216PT) exhibited ≤35.5% similarity with the pathotype strains of P. syringae pv. syringae (CFBP 1392PT, 4702T) but exhibited ≥90.6% with the YB strains (YB 12–1, YB 12–4, YB 09–1). Also, the YB strains (YB 12–1, YB 12–4, YB 09–1) were able to infect only onion but not oat, rye and Italian ryegrass (common hosts for P. syrinage pv. coronafaciens). Contrastingly, P. syringae pv. coronafaciens strains (NCPPB 600PT, ATCC 19608, Pcf 83–300) produced typical halo blight symptoms on oat, rye and Italian rye grass but did not produce any symptoms on onion. These results provide evidence that P. syringae pv. coronafaciens should be elevated to a species level and the new YB strains may potentially be a novel pathovar of hereto proposed P. coronafaciens species.Data Availability Statement: The GenBank accession number for the 16S rRNA gene sequence of strain YB 12-1 is KJ720652 and those of the housekeeping gene sequences of strains YB 12-1, YB 09-1, YB 12-5, and YB 12-4 are KJ719498-KJ719501 (gyrB), KJ720640-KJ720643 (rpoD), KJ720644-KJ720647 (gap1) and KJ720648-KJ720651 (gltA), respectively.Vidalia Onion Committeehttp://www.plosone.orgForestry and Agricultural Biotechnology Institute (FABI)Microbiology and Plant Patholog

Interactions Between <i>Frankliniella fusca</i> and <i>Pantoea ananatis</i> in the Center Rot Epidemic of Onion (<i>Allium cepa</i>)

An Enterobacteriaceae bacterium, Pantoea ananatis (Serrano) Mergaert, is the causal agent of an economically important disease of onion, center rot. P. ananatis is transmitted by an onion-infesting thrips, Frankliniella fusca (Hinds). However, interactions between F. fusca and P. ananatis as well as transmission mechanisms largely remain uncharacterized. This study investigated P. ananatis acquisition by thrips and transstadial persistence. Furthermore, the effects of bacterial acquisition on thrips fitness were also evaluated. When thrips larvae and adults were provided with acquisition access periods (AAP) on peanut leaflets contaminated with the bacterium, an exponentially positive relationship was observed between AAP and P. ananatis acquisition (R2 ≥ 0.77, P = 0.01). P. ananatis persisted in thrips through several life stages (larvae, pupae, and adult). Despite the bacterial persistence, no significant effects on thrips fitness parameters such as fecundity and development were observed. Immunofluorescence microscopy of adult thrips with P. ananatis-specific antibody after 48 h AAP on contaminated food revealed that the bacterium was localized only in the gut. These results suggested that the pathogen is not circulative and could be transmitted through feces. Mechanical inoculation of onion seedlings with fecal rinsates produced center rot symptoms, whereas inoculation with rinsates potentially containing salivary secretions did not. These results provide evidence for stercorarian transmission (transmission through feces) of P. ananatis by F. fusca. </jats:p

Pseudomonas coronafaciens sp. nov., a new phytobacterial species diverse from Pseudomonas syringae.

We propose Pseudomonas coronafaciens sp. nov. as a new species in genus Pseudomonas, which is diverse from P. syringae. We also classified strains from onions which are responsible for yellow bud (YB) disease as P. coronafaciens. Sequencing of 16S rRNA gene and multi-locus sequence analysis (MLSA) of housekeeping genes (gyrB, rpoD, gltA and gap1 genes) for the P. syringae pv. coronafaciens strains along with other strains of P. syringae pathovars resulted in a distinct cluster separate from other P. syringae pathovars. Based on DNA-DNA relatedness, pathotype strain of P. syringae pv. coronafaciens (CFBP 2216PT) exhibited ≤35.5% similarity with the pathotype strains of P. syringae pv. syringae (CFBP 1392PT, 4702T) but exhibited ≥90.6% with the YB strains (YB 12-1, YB 12-4, YB 09-1). Also, the YB strains (YB 12-1, YB 12-4, YB 09-1) were able to infect only onion but not oat, rye and Italian ryegrass (common hosts for P. syrinage pv. coronafaciens). Contrastingly, P. syringae pv. coronafaciens strains (NCPPB 600PT, ATCC 19608, Pcf 83-300) produced typical halo blight symptoms on oat, rye and Italian rye grass but did not produce any symptoms on onion. These results provide evidence that P. syringae pv. coronafaciens should be elevated to a species level and the new YB strains may potentially be a novel pathovar of hereto proposed P. coronafaciens species