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Copyright of Journal of Agriculture & Nature / Kahramanmaraş Sütçü İmam Üniversitesi Tarım & Doğa Dergisi is the property of Kahramanmaras Sutcu Imam Universitesi and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Bacterial spot a significant disease that affects tomato crops, despite limited studies and scientific research on this disease, So This study aimed to assess the efficacy of various biological and chemical factors in controlling bacterial spot disease in the field. A field survey was conducted in Najaf Al-Ashraf, specifically in areas such as Al-Haidariya, Al-Rahima, Al-Abbasia, and 20 plastic houses. The disease incidence was observed in these locations, with infection rates from 24% to 60%. Among them, Al-Haidariya had the highest infection rate at 60%, while Al-Abbasia had the lowest at 24%. Regarding to the impact of chemical and biological inducing factors on infection severity, the treatment using nanoscale zinc oxide demonstrated superior effectiveness in reducing the severity of infection caused by Xanthomonas campestris pv. vesicatoria, In reducing the severity of the infection, which amounted to 11.6%, compared with the treatment of X.campestris 2 (control 2) only, which amounted to 74.2%.Field results also indicated that the nanoscale zinc oxide treatment was highly effective in increasing chemical indicators such as chlorophyll content, peroxidase enzyme and catalase enzyme. The values for these indicators were 12.69 mg g-1, 183.25-unit min-1 g -1 FW and 177.84-unit min-1 g -1 FW, respectively, compared to the control treatment, which recorded values of 7.79 mg g-1, 88.3-unit min-1 g -1 FW, and 74.17-unit min-1 g -1 FW, respectively. Furthermore, the treatment using Pseudomonas putida demonstrated superiority in increasing the percentage of TSS, vitamin C content, and acid percentage. The values for these parameters were 8.45%, 20.86 mg g-1, and 0.862%, respectively, compared to the control treatment, which recorded values of 4.78%, 11.09 mg g-1 and 0.462%, respectively. Moreover, the nanoscale zinc oxide treatment exhibited superior effectiveness in increasing the yield per plant, early fruit yield per plant, and total yield. The values for these parameters were 7.54 kg plant-1, 10.261 kg. plant-1 and 8.591 tons plastichouse-1 (500 m²), respectively, compared to the control treatment, which recorded values of 4.15 kg plant-1, 3.752 kg plant-1, and 4.929 tons/plastic house (500 m²), respectively. [ABSTRACT FROM AUTHOR]

Copyright of Nativa is the property of Revista Nativa and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Rose, a plant belonging to the family Rosaceae, is one of the most popular and versatile flowering shrubs in urban landscape areas. In recent years, rose bacterial diseases are getting to increase and they cause significant economic losses. The severity and distribution of these problems change every year according to the changing climatic factors, growing areas, the type of roses and the level of being affected by biotic and abiotic factors. In this study, on the 106 rose cultivars located in landscape areas of Konya province was determined different diseases symptoms at various levels by carried out survey studies in 1998-2022 years. As a result of the diagnosis of obtaining bacterial and fungal isolates, bacterial blights (Pseudomonas syringae pv. syringae and P. s. pv. morsprunorum), Xanthomonas hortorum, fire blight (Erwinia amylovora) and crown gal (Rhizobium radiobacter), downy mildew (Peronospara sparsa), rust (Phragmodium mucronatum), black spot (Diplocarpon rosae), powdery mildew (Sphaerotheca pannosa var. rosae), gray mold (Botrytis cinerea) were determined as the pathogen on the rose cultivars. It is thought that the findings obtained from the study will contribute to the future development of rose cultivation by revealing the different pathogens and disease levels in roses as a result of the changing climatical conditions. [ABSTRACT FROM AUTHOR]

The system Nicotiana tabacum L.—Pseudomonas syringae VAN HALL pv. tomato (Pto) DC3000 was investigated at a low inoculation level (c. 5 × 105 colony-forming units (CFU) mL–1) such as it occurs in the field. The aim of this study was to test the hypothesis that N. tabacum, a non-host of Pto DC3000, improved the PSII efficiency in inoculated leaves compared with control detached leaves. Visible symptoms at the infected area were not detected within 14 days. Chlorophyll (Chl) a fluorescence was measured 6–7 days after inoculation of detached leaves. Compared with the control, the actual photochemical quantum yield of photosystem (PS) II was higher in the inoculated leaves at the expense of the fraction of heat dissipated by photo-inactivated non-functional centers. In addition, the fraction of open PSII reaction centers (RCs) was higher in inoculated leaves. Maximum fluorescence in the dark-adapted detached inoculated leaves, as a measure of the absorbed energy, was lower than in control leaves. The lower capacity to absorb energy in combination with a higher fraction of open PSII RCs is interpreted as an acclimation to limit over-excitation and to reduce heat dissipation. This should limit the production of reactive oxygen species and reduce the probability of a hypersensitive response (HR), which represents an expensive cell-death program for the plant. [ABSTRACT FROM AUTHOR]

Phytopathogenic bacteria in the plant organism form an integral part of the accompanying microflora, as well as pathogens of pathological processes that do not just weaken the plant, but shortly (with acute pathogenesis) lead to degradation and complete dieback. Notably, bacteriosis is described by typical macroscopic signs of the course of the disease, but the exact aetiology of the pathological process can be reliably established only based on bacteriological analysis with the identification of morphological, cultural, and biochemical properties of isolates. The purpose of this study is to experimentally confirm the direct causes of oak degradation caused by bacterial wetwood in the tree stands under study, as well as to investigate the morphological and biochemical properties of the pathogen. This study employed classical microbiological, phytopathological, and biochemical methods that establish the aetiology of the disease, analyse typical symptoms, include microscopy of the affected parts of the oak, isolation, and identification of the pathogen. The properties of bacterial isolates were figured out according to generally accepted methods and using the API 20E test system and the NEFERMtest24 MikroLaTEST®, ErbaLachema a test system. It was experimentally confirmed that by all macroscopic signs (crown openness, exudate discharge from bark cracks, presence of depressed (sunken) necrotic wet wounds in certain areas of cracks, development of a wet pathological core, presence of epicormic sprouts, etc.) the identified disease is a systemic, vascular-parenchymal bacteriosis, known as bacterial wetwood of common oak. The isolated bacterial isolates were identified by morphological, physiological, and biochemical properties as Lelliottia nimipressuralis – the causative agent of bacterial wetwood of common oak. This suggests that the aetiology of degradation of common oak in Ukraine is closely related to bacteriosis, and the results of this study allow for early phytosanitary diagnostics of the state of common oak in natural conditions based on typical symptomatic signs. [ABSTRACT FROM AUTHOR]

Ralstonia pseudosolanacearum GMI1000 (Rpso GMI1000) is a soil-borne vascular phytopathogen that infects host plants through the root system causing wilting disease in a wide range of agro-economic interest crops, producing economical losses. Several features contribute to the full bacterial virulence. In this work we study the participation of light, an important environmental factor, in the regulation of the physiological attributes and infectivity of Rpso GMI1000. In silico analysis of the Rpso genome revealed the presence of a Rsp0254 gene, which encodes a putative blue light LOV-type photoreceptor. We constructed a mutant strain of Rpso lacking the LOV protein and found that the loss of this protein and light, influenced characteristics involved in the pathogenicity process such as motility, adhesion and the biofilms development, which allows the successful host plant colonization, rendering bacterial wilt. This protein could be involved in the adaptive responses to environmental changes. We demonstrated that light sensing and the LOV protein, would be used as a location signal in the host plant, to regulate the expression of several virulence factors, in a time and tissue dependent way. Consequently, bacteria could use an external signal and Rpsolov gene to know their location within plant tissue during the colonization process. [ABSTRACT FROM AUTHOR]

Moderate to severe disease incidence was recorded in a wide range of average soil pH, EC and organic carbon. A reverse relationship between soil EC and the disease incidence was recorded. Disease incidence was lower in the areas closer to river side. Among the cultivated solanaceous vegetables, potato and chilli were found comparatively less affected to this disease. Occurrence of the disease throughout the year posed an alarming situation in Sundarban region of West Bengal. [ABSTRACT FROM AUTHOR]

The General Beale Pilot Project serves as a case study for the use of areawide monitoring and treatment programs for glassy-winged sharpshooter (GWSS), Homalodisca vitripennis (Germar), and monitoring and roguing programs for grapevines infected with Xylella fastidiosa, to achieve regional management of Pierce's disease. The Project is located in southeast Kern County, CA, and contains ~2,800 ha of citrus and grapevines grown within approximately 50 km2. For nearly 20 yr, an average of 470 traps have been used to monitor GWSS populations regionally by the California Department of Food and Agriculture, and to inform coordinated, areawide treatments by the USDA-APHIS Areawide Treatment Program to overwintering GWSS in citrus. Grape growers were responsible for treating their own vineyards, and for the roguing of infected grapevines based on surveys provided by the University of California. Herein, we provide a history of the General Beale Pilot Project, broken down into six eras based on levels of Project success, which incorporate data on GWSS captures, pesticide use, and disease incidence. We describe patterns of success related to the regional coordination of effective treatment and roguing programs that can be used by grape and neighboring citrus growers for areawide management of Pierce's disease. We conclude by describing current and future challenges for Pierce's disease management, including pesticide availability and resistance, GWSS refuges, the inability to detect and rogue infected vines in the year they become infected, and the sustainability of voluntary programs that rely on public funding. [ABSTRACT FROM AUTHOR]

Bacterial leaf blight (BLB) disease, which is caused by Xanthomonas oryzae pv oryzae, is one of the devastating biotic stress in rice that results in yield losses. Cultivation of the resistant rice varieties has been proven as an environment-friendly and effective approach to address this problem. As such, this study developed a high quality and tightly linked marker of Xa7 gene, a resistant gene that controls BLB disease in rice. In this study, the mapping population of MR263 X IRBB7 was generated. The F2 population was used for genotyping purpose, while the F2:3 lines were employed for phenotyping purpose. Both genotyping and phenotyping data were used in bulk segregant analysis to narrow down the Xa7 region. A total 87 SNP markers were developed to genotype the mapping population. Out of 87 SNPs, only 65 SNPs exhibited acceptable call rates, and this was followed the Mendelian ration of F2 population (1:2:1). This study had successfully narrowed down the region of Xa7 from 118.5 kb to 58.5 kb, flanked by SNP_Xa7_14 and SNP_Xa7_31 that composed of 13 SNP markers. The developed SNP markers, which were tightly linked to Xa7 gene, emerge to be greatly significant in marker-assisted breeding activity to introgress BLB resistant gene into susceptible rice varieties. The application of the developed SNP marker is bound to enhance both efficiency and accuracy in the selection. The linkage drag phenomenon may be minimised as well as the marker is highly close to the target gene. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Agriculture & Nature / Kahramanmaraş Sütçü İmam Üniversitesi Tarım & Doğa Dergisi is the property of Kahramanmaras Sutcu Imam Universitesi and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Huanglongbing (HLB) is a disease that has devastated the Florida citrus industry, threatens the entire U.S. citrus industry, and globally is rapidly spreading. Florida's citrus production is 90% sweet orange, which is quite sensitive to HLB. The heavy reliance on sweet orange for Florida citrus production makes the industry especially vulnerable to diseases that are damaging to this type of citrus. Furthermore, 90% of Florida oranges are used in producing orange juice that is defined by a federal regulation known as the "orange juice standard", specifying that at least 90% of "orange juice" must be derived from Citrus sinensis. Genomic analyses definitively reveal that sweet orange is not a true species, but just one of many introgression hybrids of C. reticulata and C. maxima, with phenotypic diversity resulting from accumulated mutations in this single hybrid, the "sweet orange". No other fruit industry is limited by law to such a narrow genetic base. Fortunately, there are new citrus hybrids displaying reduced sensitivity to HLB, and in some cases they produce juice, alone or in blends, that consumers would recognize as "orange juice". Reconsidering current regulations on orange juice standards may permit use of such hybrids in "orange juice", providing greater latitude for commercialization of these hybrids, leading to higher-quality orange juice and a more sustainable Florida orange juice industry. [ABSTRACT FROM AUTHOR]

In 2018, severe bacterial blight was observed on Dracaena sanderiana plants imported and cultivated by a commercial nursery in Jinju, South Korea. This indoor plant is popularly grown for indoor air purification to prevent sick building syndrome (SBS). The diseased plants had severe blight symptoms, with leaf chlorosis and crumpling of stem and leaves. To identify the causal agent, we performed bacterial isolation, pathogenicity tests, physiological analysis, sequencing of the 16S rRNA region and recA gene, and phylogenetic analysis; the bacterial pathogen was identified as Burkholderia cepacia. This is the first report of bacterial blight on D. sanderiana caused by B. cepacia. Although there is no clear epidemiological information on the inoculum source, the recent occurrence of the disease indicates that B. cepacia is a potential threat to the production of indoor dracaena plants, which are increasingly used for air purification in SBS. Because D. sanderiana is grown in indoor living spaces, B. cepacia infection could threaten human health as well. [ABSTRACT FROM AUTHOR]

Cross‐contamination of Pectobacterium carotovorum subsp. carotovorum (PCC) from a stainless‐steel surface to cabbage (Brassica rapa L. subsp. pekinensis) was evaluated. To investigate the PCC transfer pattern from mechanical knife surfaces to cabbage during 100 cuts, two mathematical models (power and logarithmic model) were fitted to the mean log10 detection data from cabbage. Overall, regression analysis determined that the best‐fitting regression curves of planktonic cells and detached cells from biofilms transferred onto fresh cabbage were Y = 3.7X–0.41, RMSE = 0.371 and Y = 4.6X–0.35, RMSE = 0.254, respectively. For salted cabbage, the best‐fit regression curves of planktonic cells and biofilm were Y = 5.8X–0.38, RMSE = 0.209 and Y = 5.4X–0.23, RMSE = 0.195, respectively. Our data provide a meaningful indication of the level of PCC cross‐contamination. [ABSTRACT FROM AUTHOR]

Potato blackleg disease (PBD) is one of the most serious potato bacterial diseases. Although the importance of the rhizosphere microbiota for plant growth and health is widely acknowledged, the relationship between the composition of the rhizosphere microbiota and PBD is still unclear. To analyze the relationship between the rhizosphere microbiota composition and PBD, we firstly investigated the potato rhizosphere microbiota composition in the settings of PBD, suspected PBD (SPBD), and health using high-throughput sequencing of 16S rRNA genes. We found that PBD was closely related to the composition of the rhizosphere microbiota. Flavobacterium , Acinetobacter , Dickeya , Sphingobacterium , and Myroides were more abundant in the rhizosphere microbiota of potatoes with PBD than in that of healthy potatoes, while Bacillus , Rhodoplanes , Kaistobacter , Pedobacter , and an unidentified genus from Gaiellaceae were less abundant in the setting of PBD. Dickeya was the probable PBD pathogen in the present study. Our results indicated that enhancing Bacillus may be a way to prevent PBD. These findings provide new insights for the diagnosis and prevention of PBD. Unlabelled Image • Potato blackleg disease was closely related to the composition of the rhizosphere microbiota. • Dickeya was the probable potato blackleg disease pathogen in the present study. • Enhancing Bacillus in potato plant soil may be a way to prevent potato blackleg disease. [ABSTRACT FROM AUTHOR]

The causative agents of bacterial spot disease infecting pepper are the species X. euvesicatoria and X. vesicatoria common in the typical pepper growing areas (Northern: Black Sea Costal and Central; Southwest; Southern - Upper Thracian valley) in Bulgaria. The pathogens refer to pepper P pathotype (22 strains) and pepper-tomato P pathotype (52 strains). The natural population of X. euvesicatoria is heterogeneous of pathotype and physiological races. Widespread is race P6 in the P of the pathogen, followed by race P1. Single strains are assigned to P3, P9 and P10. In PT, races P0, P1, P4, P5 are differentiated, the dominant race in PT is the P4 race in combination with the tomato race T2. For the first time in Bulgaria in the natural population of X. vesicatoria, are detected strains which infect only pepper, differentiated are races P0, P2 and P3. The population of X. vesicatoria PT prevails in private gardens and vegetable areas near tomatoes. Differentiated races are P1, P3 and P4 in combination with tomato races T1, T2 and T3. Race P3 occurs in P and PT pathotype. [ABSTRACT FROM AUTHOR]

Purpose: Pseudomonas syringae pv. actinidiae causes bacterial canker of kiwifruit and is responsible for severe economic losses and emergence of drug-resistant bacteria. Bacteriophages are viruses that infect target bacterial hosts and may be the best strategy to prevent and control kiwifruit canker disease. The objective of this experiment was to monitor the prevalence of Pseudomonas syringae pv. actinidiae and provide insight for the use of phages in biological control. Materials and methods: In this study, 52 strains of Pseudomonas syringae pv. actinidiae were isolated from 68 stem samples of kiwi plant (cv. Hongyang & Jinkui). Following polymerase chain reaction (PCR) analysis, 15 isolates belonging to biovar 3 were identified, one of which was named XWY0007 and used as the target strain to isolate the phages. Thirty-six phages were isolated and purified from a total of 51 surface water samples collected in Shanghai. All phages were identified by transmission electron microscopy (TEM) and their host ranges were evaluated. Three phages, designated φXWY0013, φXWY0014 and φXWY0026 were selected and further characterised using one-step growth curve and stability at different temperatures and pH. Results and conclusions: The isolated phages are promising for use as antimicrobials against bacterial canker in kiwi. This report is regarding Pseudomonas syringae pv. actinidiae and its phages from major areas of kiwifruit cultivation. [ABSTRACT FROM AUTHOR]

In the late winter of 2016, an unusual bacterial disease was suspected of causing severe wet rot (tip over) of banana plants grown in various greenhouses in the Mersin province of Turkey. The symptoms of the disease included small round or irregular areas of wet rot, collar rotting, yellowing of the leaves, sucker tip over, and plant death. Infected pseudo-stem samples were collected for isolation of the putative pathogen. The pathogen was identified as Pectobacterium carotovorum subsp. carotovorum (Pcc) after subjecting all isolates to conventional nested PCR with EXPCCF/EXPCCR and INPCCR/INPCCF primer sets, which produced amplification fragments of 550 and 400 bp in the first and the second PCR reactions, respectively. BLAST analysis of amplified PCR products of pel gene and 16S rRNA and the phylogenetic relationships among the various Pcc strains showed high similarities, which ranged from 99–100% with those retrieved from the NCBI GenBank nucleotide database. Real-time PCR was conducted using a locked nucleic acid (LNA) probe specific to Pcc. The pathogenicity tests of all the Pcc isolates were confirmed on banana cultivar 'Grand Naine' and potato slices by inoculation with bacterial suspension and subsequent re-isolation of the pathogen from the infected plants. To our knowledge, this is the first time Pcc has been detected, identified and implicated as the causal agent of wet rot disease of banana plants in Turkey. [ABSTRACT FROM AUTHOR]

A new disease on sesame (Sesamum indicum L.) plants was observed in the municipalities of Ahome, El Fuerte and Choix in the state of Sinaloa, Mexico during the summer of 2014. The disease occurred during the rainy season (August–September) when temperatures ranged between 27–40°C. The symptoms were lesions on leaves, petioles, stems and capsules. Up to 100% incidence was observed, and up to 50% of the foliage exhibited symptoms under field conditions. Isolations were made from leaves and a bacterium was consistently recovered on nutrient agar medium. Based on physiological and biochemical tests, as well as sequences from three different DNA regions, the bacterium was identified as Xanthomonas campestris pv. sesami. Pathogenicity tests confirmed the ability of select isolates to cause symptoms similar to those observed under field conditions. [ABSTRACT FROM AUTHOR]

Coffee is a very important crop for several tropical countries across different continents. The diseases bacterial halo blight (BHB), bacterial leaf spot (BLS), bacterial leaf blight (BLB) and coffee leaf scorch (CLS), caused by the bacterial pathogens Pseudomonas syringae pv. garcae (Psgc), P. syringae pv. tabaci (Psta), Pseudomonas cichorii (Pch) and Xylella fastidiosa subsp. pauca (Xfp), respectively, cause significant reductions in coffee production, although other minor bacterial diseases have also been reported in some countries. Little research progress has been made on aspects that are relevant for control and management of these diseases. In all cases, there is an urgent need to develop rapid and more reliable methods for early detection of the pathogens in order to minimize their negative impact on coffee production. Because of the high rate of intra‐ and intersubspecific recombination occurring in X. fastidiosa, a permanent revision of the detection methods is necessary. Greater efforts should be made to understand the genetic and virulence diversity of Psgc, Psta and Pch populations. Early studies reported the identification of potential sources of resistance against Psgc and Psta, but, to date, no resistance gene has been isolated. Little effort has been made to understand the biology and molecular mechanisms underlying the interaction between Coffea spp. and these pathogenic bacteria. This review discusses the recent progress on the molecular mechanisms used by these bacteria to cause diseases on other plant species, in order to provide a guideline for the establishment of future research programmes. [ABSTRACT FROM AUTHOR]

Extensive use of chemical pesticides poses a great threat to the environment and food safety. The discovery of Bacillus thuringiensis (Bt) toxins with effective insecticidal activity against pests and the development of transgenic technology of plants opened a new era of pest control. Transgenic Bt crops, including maize, cotton and soya bean, have now been produced and commercialized to protect against about 30 major coleopteran and lepidopteran pests, greatly benefiting the environment and the economy. However, with the long-term cultivation of Bt crops, some target pests have gradually developed resistance. Numerous studies have indicated that mutations in genes for toxins activation, toxin-binding and insect immunization are important sources in Bt resistance. An in-depth exploration of the corresponding Bt-resistance mechanisms will aid in the design of new strategies to prevent and control pests. Future research will focus on Bt crops expressing new genes and multiple genes to control a broader range of pests as part of an integrated pest management programme. [ABSTRACT FROM AUTHOR]

Pseudomonas syringae pv. actinidiae causes kiwifruit bacterial canker, with severe infection of the kiwifruit plant resulting in heavy economic losses. Little is known regarding the biodiversity and genetic variation of populations of P. syringae pv. actinidiae in China. A collection of 269 strains of P. syringae pv. actinidiae was identified from 300 isolates obtained from eight sampling sites in five provinces in China. The profiles of 50 strains of P. syringae pv. actinidiae and one strain of P. syringae pv. actinidifoliorum were characterized by Rep-, insertion sequences 50, and randomly amplified polymorphic DNA polymerase chain reaction (PCR). Discriminant analysis of principal coordinates, principal component analysis, and hierarchical cluster analysis were used to analyze the combined fingerprints of the different PCR assays. The results revealed that all isolates belonged to the Psa3 group, that strains of P. syringae pv. actinidiae from China have broad genetic variability that was related to source geographic region, and that Chinese strains can be readily differentiated from strains from France but are very similar to those from Italy. Multilocus sequence typing of 24 representative isolates using the concatenated sequences of five housekeeping genes (cts, gapA, gyrB, pfk, and rpoD) demonstrated that strain Jzhy2 from China formed an independent clade compared with the other biovars, which possessed the hopHl effector gene but lacked the ItopAI effector gene. A constellation analysis based on the presence or absence of the four loci coding for phytotoxins and a cluster analysis based on the 11 effector genes showed that strains from China formed two distinct clades. All of the strains, including K3 isolated in 1997 from Jeju, Korea, lacked the cfl gene coding for coronatine. In contrast, the tox-argK gene cluster coding for phaseolotoxin was detected in K3 and in the biovar 1 strains (K3, Kw30, and Psa92), and produced a falsepositive amplicon for the /topA A7/-like gene in this study. To date, only one biovar (biovar 3) is represented by the strains of P. syringae pv. actinidiae from China, despite China being the center of origin for kiwifruit. [ABSTRACT FROM AUTHOR]

Kiwifruit bacterial canker is a devastating disease threatening kiwifruit production. To clarify the defense mechanism in response to Pseudomonas syringae pv. actinidiae (Psa), we observed phenotypic changes in resistant Huate (HT) and susceptible Hongyang (HY) kiwifruit varieties at 0, 12, 24, 48, 96, and 144 hour after inoculation (hai) with Psa. Brown lesions appeared in the inoculation areas 12 hai in HY shoots, and the lesion length gradually increased from 24 to 144 h. In contrast, no lesions were found in HT shoots at any time points. Furthermore, RNA-seq analysis showed significantly more differentially expressed genes between HT and HY at 12 hai than at any other time point. According to weighted gene co-expression network analysis, five modules were notably differentially expressed between HT and HY; pathway mapping using the Kyoto Encyclopedia of Gene and Genomes database was performed for the five modules. In MEgreenyellow and MEyellow modules, pathways related to“plant-pathogen interaction”, “Endocytosis”, “Glycine, serine and threonine metabolism”, and “Carbon fixation in photosynthetic organisms” were enriched, whereas in the MEblack module, pathways related to “protein processing in endoplasmic reticulum”, “plant-pathogen interaction”, and “Glycolysis / Gluconeogenesis” were enriched. In particular, the Pti1 and RPS2 encoding effector receptors, and the NPR1, TGA, and PR1 genes involved in the salicylic acid signaling pathway were significantly up-regulated in HT compared with HY. This indicates that the effector-triggered immunity response was stronger and that the salicylic acid signaling pathway played a pivotal role in the Psa defense response of HT. In addition, we identified other important genes, involved in phenylpropanoid biosynthesis and Ca2+ internal flow, which were highly expressed in HT. Taken together, these results provide important information to elucidate the defense mechanisms of kiwifruit during Psa infection. [ABSTRACT FROM AUTHOR]

Bacterial blight (BB) caused by the Xanthomonas oryzae pv. oryzae (Xoo) pathogen is a significant disease in most rice cultivation areas. The disease is estimated to cause annual rice production losses of 20–30 percent throughout rice-growing countries in Asia. The discovery and deployment of durable resistance genes for BB is an effective and sustainable means of mitigating production losses. In this study QTL analysis and fine mapping were performed using an F2 and a BC2F2 population derived from a cross with a new R-donor having broad spectrum resistance to Korean BB races. The QTL qBB11 was identified by composite interval mapping and explained 31.25% of the phenotypic variation (R2) with LOD values of 43.44 harboring two SNP markers. The single major R-gene was designated Xa43 (t). Through dissection of the target region we were able to narrow the region to within 27.83–27.95 Mbp, a physical interval of about 119-kb designated by the two flanking markers IBb27os11_14 and S_BB11.ssr_9. Of nine ORFs in the target region two ORFs revealed significantly different expression levels of the candidate genes. From these results we developed a marker specific to this R-gene, which will have utility for future BB resistance breeding and/or R-gene pyramiding using marker assisted selection. Further characterization of the R-gene would be helpful to enhance understanding of mechanisms of BB resistance in rice. [ABSTRACT FROM AUTHOR]

Twenty five isolates of Acidovorax avenae subsp. avenae causing bacterial leaf streak collected from infected maize crop grown in different geographical regions of Punjab, northern India were characterized for their molecular diversity using twenty five random amplified polymorphic DNA (RAPD) markers. All the primers showed amplification with a total of 1769 amplified fragments. Among RAPD primers, S112 was found to be highly polymorphic with PIC value of 0.95 while OPT-4 was least polymorphic. The size of amplified DNA fragments ranged from 59 bp to 3.9 kbp. Dendrogram based on molecular data generated by 25 RAPD collectively divided all 25 isolates into four groups. From 25 isolates, 20 were used for their pathological characterization and based on the multivar cluster analysis of pathogenicity data, these were divided into three groups, each producing a distinct range of disease score on particular maize inbred/hybrid used in this study. Isolate Aaa2 was found to be the most virulent with an average disease score of 8.6, whereas Aaa17 was found least virulent with average disease score of 5.1. The most virulent isolates of this pathogen were present in central Punjab. This was the first attempt to study the genetic diversity and pathogenic variation in Punjab populations of A. avenae subsp. avenae. [ABSTRACT FROM AUTHOR]

Thiamin diphosphate (ThDP) analogs have been designed and synthesized based on the ThDP binding site of the pyruvate dehydrogenase multienzyme complex E1 of Escherichia coli. This study investigated the effect of 66 novel ThDP analogs on rice bacterial brown stripe pathogen Acidovorax avenae subsp. avenae strain RS-1. Results indicated that three of the 66 ThDP analogs (designated as 20, 21 and 53) significantly inhibited the in vitro growth of strain RS-1. However, no obvious cell lysis and destruction was found for this rice pathogenic bacterium, which were supported by morphological evidence of transmission electron microscope. In contrast, the three ThDP analogs significantly reduced biofilm formation and the activity of the pyruvate dehydrogenase of strain RS-1. Furthermore, the differential expression of ThDP target gene and 20 secretion system related genes were revealed by using quantitative real-time PCR. Among these, the expressions of ThDP target gene and VgrG-5 under the treatment of ThDP 20 were strongly induced compared to the control, which indicated that the antibacterial mechanism of ThDP analogs may be mainly due to the changed expression of ThDP target gene and secretion system related genes rather than causing damage to cell membrane. Taken together, the application of synthesized ThDP analogs might be a tractable strategy to overcome the pathogen of rice bacterial brown stripe. [ABSTRACT FROM AUTHOR]

Bacterial diseases of orchid are widespread and constitute a serious limiting factor to the production of the terrestrial orchid, Habaneria lindleyana. Bacteria were isolated from terrestrial orchids exhibiting disease symptoms in the Chiang Mai province of Thailand. Initial symptoms were circular, water-soaked leaf spots, which became brown and surrounded by yellow haloes, then enlarged to irregularly-shaped brown blotches followed by necrosis. Pathogenicity tests proved that a bacterium caused the same symptoms on H. lindleyana leaves after inoculation. The bacterium was identified as Acidovorax avenae subsp. cattleyae based on bacteriological analyses and 16S rRNA sequence comparison. Additional pathogenicity tests indicated that an isolate of A. avenae subsp. cattleyae from H. lindleyana could cause brown spots in other orchid genera. To our knowledge, this is the first study conducted to evaluate the importance of A. avenae subsp. cattleyae as an orchid pathogen in the Chiang Mai province of Thailand. [ABSTRACT FROM AUTHOR]

The use of lactic acid bacteria (LAB) to control multiple pathogens that affect different crops was studied, namely, Pseudomonas syringae pv. actinidiae in kiwifruit, Xanthomonas arboricola pv. pruni in Prunus and Xanthomonas fragariae in strawberry. A screening procedure based on in vitro and in planta assays of the three bacterial pathogens was successful in selecting potential LAB strains as biological control agents. The antagonistic activity of 55 strains was first tested in vitro and the strains Lactobacillus plantarum CC100, PM411 and TC92, and Leuconostoc mesenteroides CM160 and CM209 were selected because of their broad‐spectrum activity. The biocontrol efficacy of the selected strains was assessed using a multiple‐pathosystem approach in greenhouse conditions. L. plantarum PM411 and TC92 prevented all three pathogens from infecting their corresponding plant hosts. In addition, the biocontrol performance of PM411 and TC92 was comparable to the reference products (Bacillus amyloliquefaciens D747, Bacillus subtilis QST713, chitosan, acibenzolar‐S‐methyl, copper and kasugamycin) in semi‐field and field experiments. The in vitro inhibitory mechanism of PM411 and TC92 is based, at least in part, on a pH lowering effect and the production of lactic acid. Moreover, both strains showed similar survival rates on leaf surfaces. PM411 and TC92 can easily be distinguished because of their different multilocus sequence typing and random amplified polymorphic DNA profiles. The use of lactic acid bacteria bacteria to control multiple pathogens that affect different crops was studied, namely, Pseudomonas syringae pv. actinidiae in kiwifruit, Xanthomonas arboricola pv. pruni in Prunus and Xanthomonas fragariae in strawberry. A screening procedure based on in vitro and in planta assays of the three bacterial pathogens was successful in selecting Lactobacillus plantarum PM411 and TC92 strains as biological control agents with broad‐spectrum activity. [ABSTRACT FROM AUTHOR]

Summary: The identification of chemical compounds that prevent and combat bacterial diseases is fundamental for crop production. Bacterial virulence inhibitors are a promising alternative to classical control treatments, because they have a low environmental impact and are less likely to generate bacterial resistance. The major virulence determinant of most animal and plant bacterial pathogens is the type III secretion system (T3SS). In this work, we screened nine plant extracts and 12 isolated compounds—including molecules effective against human pathogens—for their capacity to inhibit the T3SS of plant pathogens and for their applicability as virulence inhibitors for crop protection. The screen was performed using a luminescent reporter system developed in the model pathogenic bacterium Ralstonia solanacearum. Five synthetic molecules, one natural product and two plant extracts were found to down‐regulate T3SS transcription, most through the inhibition of the regulator hrpB. In addition, for three of the molecules, corresponding to salicylidene acylhydrazide derivatives, the inhibitory effect caused a dramatic decrease in the secretion capacity, which was translated into impaired plant responses. These candidate virulence inhibitors were then tested for their ability to protect plants. We demonstrated that salicylidene acylhydrazides can limit R. solanacearum multiplication in planta and protect tomato plants from bacterial speck caused by Pseudomonas syringae pv. tomato. Our work validates the efficiency of transcription reporters to discover compounds or natural product extracts that can be potentially applied to prevent bacterial plant diseases. [ABSTRACT FROM AUTHOR]

The spread of Goss's bacterial wilt and leaf blight of corn (Zea mays), caused by Clavibacter michiganensis subsp. nebraskensis, to a wider geographic range in the early 2000s compared with the late 1960s has generated concern about the possible role of seed transmission in long-distance spread. The objectives of this research were: (1) to determine the percentage of seed infection found in seed harvested from inoculated and noninoculated plants of hybrids that varied in resistance to Goss's wilt; and (2) to estimate the seed transmission rate from these infected seed lots. The greatest percent seed infection was detected in seed from inoculated plants of the most susceptible hybrid and the least in seed from the most resistant hybrid. Seed lots with seed infection that ranged from 3.6 to 37.0% were planted in three field and three greenhouse trials. A total of 12 seed transmission events (Goss's wilt symptomatic seedlings) were identified among 241,850 plants examined, for a seed transmission rate of 0.005%. When the seed transmission rate was recalculated to consider only the infected seed portion of each seed lot, the rate increased to 0.040% (12 events from 30,088 potentially infected plants). Based on the low seed transmission rate observed and previous research on disease spread from a point source, it seems unlikely that seed transmission could introduce enough inoculum to create a serious disease outbreak in a single growing season. However, risk of seed transmission is relevant for phytosanitary restrictions and preventing the introduction of the pathogen to new areas. To date, Goss's wilt has not been detected outside North America, and while the risk of seed transmission is very low, the risk is not zero. Fortunately, the presence of C. michiganensis subsp. nebraskensis in corn seed is readily detectable by established seed health testing methods. [ABSTRACT FROM AUTHOR]

Horizontal gene transfer (HGT) to plant organelles occurs as interorganismal transfer or as promiscuous transfer. This study looks at HGT involving four tRNA genes in plant/algal mitochondrial, chloroplast, cyanobacterial, α-proteobacterial, and chlamydial genomes. A total of 64 trnN-GUU, 56 trnS-GCU, 50 trnD-GUC, and 41 trnQ-UUG sequences previously deposited in GenBank were selected and analyzed. This includes data corresponding to trnN-GUU (11 sequences) and trnS-GCU (12 sequences) genes that were previously assessed in the context of HGT. None of the trnD-GUC and trnQ-UUG sequences have been evaluated previously. Phylogenetic results for trnN-GUU and trnS-GCU agreed with an earlier hypothesis of HGT between chlamydial and mitochondrial genomes. New examples of possible HGT from a chlamydial genome are presented for trnN-GUU: 1) Dryopteris blanfordii (chloroplast), 2) Psilotum nudum (mitochondrial), and 3) putative pseudogene repeats for Gingko biloba (mitochondrial). No evidence of HGT from chlamydial genomes was found for trnD-GUC and trnQ-UUG. Promiscuous transfer was not found for trnS-GCU or trnD-GUC. For trnS-GCU and trnQ-UUG, αproteobacterial and cyanobacterial/chloroplast genes grouped together, suggestive of HGT. For all genes, distinct mitochondrial copies of Amborella trichopoda sequences affiliated with diverse taxa, indicative of interorganismal gene transfer. This study furnishes additional evidence of gene transfer involving tRNA genes to organellar genomes. [ABSTRACT FROM AUTHOR]

Abstract Utilization of resistant varieties is the most economical and effective strategy to control bacterial blight (BB) and brown planthopper (BPH) in rice. Yuehui9113 is a widely used elite restorer line with high combining ability, and one of its hybrids, C815S/Yuehui9113, has been designated as a check variety for late season single-cropping rice; however, both of the parental lines are susceptible to BB and BPH. To simultaneously improve resistance to both BB and BPH in Yuehui9113 and F 1 hybrids derived from it, one BB resistance gene (Xa21) and two BPH resistance genes (Bph14 and Bph15) were pyramided in Yuehui9113 using a marker-assisted backcrossing (MABC) strategy coupled with phenotypic selection in this study. Evaluation of BB and BPH resistance showed that all improved restorer lines that were homozygous for the resistance genes, and their derived F 1 hybrids crossed with C815S, were at least moderately resistant to fourteen Xanthomonas oryzae pv. oryzae (Xoo) strains except for strain FuJ. They were also resistant or highly resistant to BPH, except for the improved line BX9113-06 and its hybrid C815S/BX9113-06, suggesting that BB and BPH resistances were significantly improved compared with the parent Yuehui9113 and the original hybrid C815S/Yuehui9113. Evaluation of agronomic traits and plot yields in 2014 and 2016 suggested that the improved lines BX9113-01 and BX9113-12 and their hybrids with C815S are superior or similar to the original parental line Yuehui9113 and the original hybrid C815S/Yuehui9113 with respect to important agronomic traits, and the two hybrids showed higher yield potential than the control hybrid C815S/Yuehui9113. The results of this study show that introgression of the Xa21 , Bph14 , and Bph15 genes can significantly improve resistance to BB and BPH in Yuehui9113 and its hybrids. Thus, the improved restorer lines BX9113-01 and BX9113-12 will play an important role in breeding hybrid rice with high levels of resistance to BB and BPH in the Yangtze River valley of China. Highlights • We pyramided Xa21 , Bph14 and Bph15 genes into an elite restorer line 'Yuehui9113'. • All improved lines and F 1 hybrids with C815S had high-level resistance to BB & BPH. • C815S/BX9113-01 and C815S/BX9113-12 had higher yield potential than control hybrid. • The two hybrids could be used in rice production in the Yangtze River valley. [ABSTRACT FROM AUTHOR]

The current research was conducted to find out modification in mineral profiling of cotton after the attack of bacterial blight disease caused by Xanthomonas citri pv malvacearum. Leaves of three susceptible and resistant (un-inoculated and inoculated) cultivars were collected for the determination of alteration in ionic status. The remarkable variation (p = 5) in the ionic contents was observed across treatments, groups (un-inoculated and inoculated), types (susceptible and resistant) and varieties of cotton plants due to the infection by X. citri pv malvacearum. Nested random's effect analysis of variance revealed significant difference in ionic status (Ca, N, K, P, Mg, Zn, Cu and Fe) in leaves of cotton. Resistant type of plants expressed 2.40% and 0.19% while susceptible type showed 2.17% and 0.16% difference in concentrations of P and N respectively. Moreover, resistant type expressed 408.3, 310.2, 21.1, 2.9, 1.83 and 1.61 ppm while susceptible type showed 378.8, 270.2, 14.6, 2.4, 1.75 and 1.35 ppm difference in concentrations of Ca, K, Zn, Mg, Cu and Fe respectively. It was accomplished that resistant cultivars accumulated these ions at higher concentrations than susceptible varieties. These increased ionic contents in resistant plants strengthen the biochemical and physiological processes of the host plants which help to avoid the spread of pathogen. [ABSTRACT FROM AUTHOR]

Asiatic huanglongbing (HLB), also known as citrus greening or yellow shoot disease, is a serious disease putatively caused by the bacterium ' Candidatus Liberibacter asiaticus' Jagoueix et al. (Rhizobiales: Rhizobiaceae) (CLas) transmitted by the Asian citrus psyllid (Diaphorina citri Kuwayama (Hemiptera: Liviidae)). Plant resistance to CLas holds promise as a strategy for reducing the economic impact of HLB; thus, citrus breeders are developing new varieties and cultivars and evaluating these for resistance/tolerance to CLas. A high-throughput inoculation program was established to expedite testing of germplasm. Colonies of Asian citrus psyllid maintained on CLas-infected plants are used for the inoculations. The primary inoculation step is to cage a healthy citrus seedling with new leaf growth for a 2-wk inoculation feeding period by 20 adult Asian citrus psyllids (no regard to sex or age) from these colonies. The adults are removed after the inoculation period, and the plants are then treated with a pesticide to eliminate any adults missed or infestation of immatures. The objective here was to evaluate inoculation rates under this procedure. Ten sets of 20 healthy citrus seedlings were subjected to the procedure, one set a month, and the percentage of seedlings successfully inoculated based on testing by quantitative polymerase chain reaction were determined 6 mo after each 2-wk inoculation period. The results indicated a 77% mean transmission rate (percent infected seedlings), with rates ranging from 40 to 100%. Transmission rates were positively correlated with the percentage of Asian citrus psyllid that tested positive for CLas but not correlated with titers of CLas in these psyllids. Possible reasons for variability in transmission rates are discussed. [ABSTRACT FROM AUTHOR]

Abstract: BACKGROUND: In the last decade, diseases of bacterial origin in onions have increased and this has led to significant losses in production. These diseases are currently observed in both the Old and New Worlds. The present study aimed to evaluate whether the irrigation method influences the incidence of diseases of bacterial origin. RESULTS: In cases where the inoculum was natural, the initial incidence of soft bacterial rot did not manifest in any treatment in the first year, whereas, at the end of the conservation period, all treatments had increased incidences of infection. Sprinkler irrigation (8%) was statistically differentiated from the other treatments, for which the final incidence was similar (4.5%). For all irrigation treatments, the final incidence of bacterial soft rot decreased or remained stable towards the end of the cycle, with the exception of sprinkler irrigation in 2015, which increased. CONCLUSION: From the results of the present study, it can be inferred that the irrigation method does have an influence on the incidence of diseases of bacterial origin in the post‐harvest stage for onions. © 2018 Society of Chemical Industry [ABSTRACT FROM AUTHOR]