bacterial leaf streak
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Plant Disease ◽  
2022 ◽  
Author(s):  
Xinhua Ding ◽  
Chongchong Lu ◽  
Mingxia Hao ◽  
Lingguang Kong ◽  
Lulu Wang ◽  
...  

Rice (Oryza sativa L.) is the largest grain crop, accounting for about 40 % of the total grain production in China. In mid-July 2021, bacterial leaf streak-like disease emerged in rice varieties Chunyou584 and Yongyou2604 in Linyi city, Shandong Province, China. Disease incidences of the disease ranged from 80% to 90% in the surveyed fields. Infected rice leaves displayed dark green to yellowish-brown water-soaked thin streaks, and a large amount of beaded yellow oozes were observed on the lesions. After drying, there were gelatinous granules that were not easy to fall off and spread between leaf veins (Fig.S1A). According to the field symptoms of this disease, it was preliminarily suspected to be rice bacterial leaf streak caused by Xanthomonas oryzae pv. oryzicola (Xoc), which is a guaranteed disease in China. To isolate the causal agent, leaf discs (~1 cm2) of diseased leaves were collected from the margins of the lesions, surface sterilized and ground into pieces in sterile double distilled water. The 10-3, 10-4 and 10-5 dilutions were spread onto peptone sugar agar (PSA) and incubated at 28°C for 36 hours. Yellow mucous bacterial colonies were consistently obtained on PSA medium. To identify the pathogen, fragments of the 16S rDNA, leuS and rpoB were amplified and sequenced using the primers previously reported (Yu et al. 2021). Three strains (LY01, LY02 and LY03) showed identical colony morphology and LY01 was used for further analyses. Sequence analyses showed that the fragments of 16S rDNA (955 bp, GenBank accession number: OK261898), leuS (755 bp, GenBank accession number: OK298387) and rpoB (926 bp, GenBank accession number: OK298388) of strain LY01 shared 99.16%, 99.46% and 100% similarities with those of Pantoea ananatis TZ39 (GenBank accession numbers: CP081342.1 for 16S rDNA, MW981338.1 for leuS and MW981344.1 for rpoB), respectively, which suggest the pathogenic bacterial strain LY01 isolated is P. ananatis. In addition, the single colony of P. ananatis LY01 was shown as Fig. S2B. Furthermore, pathogenicity tests were also performed according to the following steps. Bacterial suspension at OD600=0.1 was inoculated into eight rice leaves of four healthy rice plants (Chunyou 584) at 25-33°C and 60%-80% relative humidity in the field using a clipping method (Yang et al. 2020) or spraying methods, and sterile distilled water was as negative control. The clipped leaves (Fig. S1B) and spray-inoculated leaves (Fig. S1C) showed dark green water-soaked streaks at 14 days after inoculation, respectively, which showed similar symptoms with those samples collected from the fields (Fig. S1A). On contrary, the control rice leaves remained healthy and symptomless (Fig. S2A). The bacterium was re-isolated in the inoculated rice leaves and the re-isolated bacterial isolates, which was confirmed by sequencing 16S rDNA, leuS and rpoB, incited the same symptoms as in fields, which fulfills Koch’s postulates. In the past decade, P. ananatis was reported to result in grain discoloration and leaf blight in China (Yan et al. 2010; Xue et al. 2020, Yu et al. 2021), which could result in 40% - 60% yield losses. To our best knowledge, this is the first report of the bacterial leaf streak-likely disease occurred in Shandong Province caused by P. ananatis, so we named it as Pantoea leaf streak of rice. Although P. ananatis was also reported in Zhejiang province and Jiangxi province, which caused leaf streak lesions on rice, the disease symptoms are completely different from those of Pantoea leaf streak of rice. To the best of our knowledge, this is the first report of Pantoea leaf streak of rice caused by P. ananatis. This study provides sloid evidence that Pantoea leaf streak of rice in Eastern China can be caused by the new pathogen, P. ananatis, rather than Xoc as traditionally assumed. Disease development and quarantine of the new Pantoea leaf streak of rice disease caused by P. ananatis on rice need more attention in the near future.


2021 ◽  
Vol 22 (23) ◽  
pp. 12953
Author(s):  
Chengqian Wei ◽  
Junjie Huang ◽  
Yu Wang ◽  
Yifang Chen ◽  
Xin Luo ◽  
...  

A series of new oxadiazole sulfone derivatives containing an amide moiety was synthesized based on fragment virtual screening to screen high-efficiency antibacterial agents for rice bacterial diseases. All target compounds showed greater bactericidal activity than commercial bactericides. 3-(4-fluorophenyl)-N-((5-(methylsulfonyl)-1,3,4-oxadiazol-2-yl)methyl)acrylamide (10) showed excellent antibacterial activity against Xanthomonas oryzae pv. oryzae and Xanthomonas oryzae pv. oryzicola, with EC50 values of 0.36 and 0.53 mg/L, respectively, which were superior to thiodiazole copper (113.38 and 131.54 mg/L) and bismerthiazol (83.07 and 105.90 mg/L). The protective activity of compound 10 against rice bacterial leaf blight and rice bacterial leaf streak was 43.2% and 53.6%, respectively, which was superior to that of JHXJZ (34.1% and 26.4%) and thiodiazole copper (33.0% and 30.2%). The curative activity of compound 10 against rice bacterial leaf blight and rice bacterial leaf streak was 44.5% and 51.7%, respectively, which was superior to that of JHXJZ (32.6% and 24.4%) and thiodiazole copper (27.1% and 28.6%). Moreover, compound 10 might inhibit the growth of Xanthomonas oryzae pv. oryzae and Xanthomonas oryzae pv. oryzicola by affecting the extracellular polysaccharides, destroying cell membranes, and inhibiting the enzyme activity of dihydrolipoamide S-succinyltransferase.


2021 ◽  
pp. 779-824
Author(s):  
Christina Cowger ◽  

This chapter first describes the challenges of diverse climates, diseases, and market classes that face North American small-grain cereal breeders and producers. It discusses the challenges inherent in the complex systems of cereal breeding on the continent, and the changing resistance priorities brought about by shifting pathogen races and production practices. The remainder of the chapter is devoted (in rough order of priority) to the status and prospects for durable resistance to the main pests currently confronting the continent: Fusarium head blight, rusts, powdery mildew, leaf (and glume) blotches, viruses, Hessian fly, and bacterial leaf streak.


Genes ◽  
2021 ◽  
Vol 12 (10) ◽  
pp. 1587
Author(s):  
Tripop Thianthavon ◽  
Wanchana Aesomnuk ◽  
Mutiara K. Pitaloka ◽  
Wannapa Sattayachiti ◽  
Yupin Sonsom ◽  
...  

Rice is one of the most important food crops in the world and is of vital importance to many countries. Various diseases caused by fungi, bacteria and viruses constantly threaten rice plants and cause yield losses. Bacterial leaf streak disease (BLS) caused by Xanthomonas oryzae pv. oryzicola (Xoc) is one of the most devastating rice diseases. However, most modern rice varieties are susceptible to BLS. In this study, we applied the QTL-seq approach using an F2 population derived from the cross between IR62266 and Homcholasit (HSC) to rapidly identify the quantitative trait loci (QTL) that confers resistance to BLS caused by a Thai Xoc isolate, SP7-5. The results showed that a single genomic region at the beginning of chromosome 5 was highly associated with resistance to BLS. The gene xa5 was considered a potential candidate gene in this region since most associated single nucleotide polymorphisms (SNPs) were within this gene. A Kompetitive Allele-Specific PCR (KASP) marker was developed based on two consecutive functional SNPs in xa5 and validated in six F2 populations inoculated with another Thai Xoc isolate, 2NY2-2. The phenotypic variance explained by this marker (PVE) ranged from 59.04% to 70.84% in the six populations. These findings indicate that xa5 is a viable candidate gene for BLS resistance and may help in breeding programs for BLS resistance.


Plants ◽  
2021 ◽  
Vol 10 (10) ◽  
pp. 2039
Author(s):  
Xiaofang Xie ◽  
Yan Zheng ◽  
Libin Lu ◽  
Jiazheng Yuan ◽  
Jie Hu ◽  
...  

Bacterial leaf streak (BLS) is a devastating rice disease caused by the bacterial pathogen, Xanthomonas oryzae pv. oryzicola (Xoc), which can result in severe damage to rice production worldwide. Based on a total of 510 rice accessions, trialed in two seasons and using six different multi-locus GWAS methods (mrMLM, ISIS EM-BLASSO, pLARmEB, FASTmrMLM, FASTmrEMMA and pKWmEB), 79 quantitative trait nucleotides (QTNs) reflecting 69 QTLs for BLS resistance were identified (LOD > 3). The QTNs were distributed on all chromosomes, with the most distributed on chromosome 11, followed by chromosomes 1 and 5. Each QTN had an additive effect of 0.20 (cm) and explained, on average, 2.44% of the phenotypic variance, varying from 0.00–0.92 (cm) and from 0.00–9.86%, respectively. Twenty-five QTNs were detected by at least two methods. Among them, qnBLS11.17 was detected by as many as five methods. Most of the QTNs showed a significant interaction with their environment, but no QTNs were detected in both seasons. By defining the QTL range for each QTN according to the LD half-decay distance, a total of 848 candidate genes were found for nine top QTNs. Among them, more than 10% were annotated to be related to biotic stress resistance, and five showed a significant response to Xoc infection. Our results could facilitate the in-depth study and marker-assisted improvement of rice resistance to BLS.


Plant Disease ◽  
2021 ◽  
Author(s):  
Amadou Diallo ◽  
Sylvain Zougrana ◽  
Mahamadou Sawadogo ◽  
Daouda KONE ◽  
Drissa Silué ◽  
...  

Bacterial Leaf Streak (BLS) of rice caused by Xanthomonas oryzae pv. oryzicola (Xoc) is considered as the third emerging infectious disease of rice in Africa. First reported in Africa in the 1980s, the disease is now present in at least eight African countries including Burundi, Burkina Faso, Kenya, Madagascar, Mali, Nigeria, Senegal and Uganda. Yield loss caused by BLS is estimated at 20 to 30% (Sileshi and Gebeyehu, 2021). To our knowledge BLS has so far not been reported in Ivory Coast. While BLS has not been described in the adjacent rice-growing countries Ghana and Liberia, Xoc strains isolated from samples collected between 2003 and 2011 in Burkina Faso and Mali have been characterized (Wonni et al., 2014). Xoc is transmitted through rice seeds which favors its spread through rice trading (Sileshi and Gebeyehu, 2021). Given the extensive rice trade between Burkina Faso, Mali and Ivory Coast, we hypothesized that BLS might also be present in this country. Field surveys were carried out across Ivory Coast in October 2018. Typical symptoms of the disease, e.g. translucent lesions in the form of yellow-brown to black streaks with sometimes visible droplets of exudates on the leaf surface, were observed in the area of Korhogo. 5cm-long leaf pieces were successively disinfected, rinsed in sterile water, and then ground using the Qiagen Tissue Lyser System (QIAGEN, Courtaboeuf, France). Leaf powder was resuspended in 1.5 ml of sterile water and incubated at room temperature for 30 minutes. Then, 10 μl of the suspension was streaked on semi-selective PSA medium and incubated at 28 ° C for 3 to 7 days. Colonies characteristic of Xoc, i.e. round, convex, mucous and straw yellow in color were purified from 6 individual samples from 2 distinct sites in Korhogo. To confirm their identity, isolated strains underwent a pathogenicity and molecular characterization test. The multiplex PCR developed for the identification of X. oryzae pathovars (Lang et al., 2010) revealed for all the isolates the characteristic PCR profile of Xoc (two amplicons of 324 and 691 base pairs). Strains of Xoc BLS256 and Xoo PXO99 were used as controls. The pathogenicity test was performed on 5 weeks-old plants of O. sativa cv. Azucena leaves by infiltration with a needleless syringe of a bacterial suspension at an optical density of 0.5. After 7 days of greenhouse incubation (27 ± 1°C with a 12-hour photoperiod), all infiltration points (2 infiltrations x 3 plants per isolate) developed water-soaked lesions identical to the one challenged with BLS256 while water-infiltrated leaves remained asymptomatic. These lesions were collected and subjected to the isolation and multiplex PCR processes described above, thus fulfilling Koch's postulate. Finally, three of the isolates were subjected to sequencing of the housekeeping gene gyrB by PCR amplification using the primers XgyrB1F and XgyrB1R (Young et al., 2008). Analysis of 780bp of the gyrB sequence of strains CI_k1-1, CI_k2-2 and CI_k3-2 revealed 100% identity with the gyrB sequence of Xoc reference strain BLS256 (Acc. No. CP003057) and 10 polymorphic nucleotides compared to the Xoo reference strain PXO99A (Acc. No. CP000967). To our knowledge, this is the first report of BLS in Ivory Coast supported by molecular characterization methods. New surveys in Ivory Coast and neighboring countries where the disease has not been reported will allow to implement collections and assess disease incidence as part of future control strategies.


2021 ◽  
Author(s):  
Alian Sarkes ◽  
Yalong Yang ◽  
Snezana Dijanovic ◽  
Michael Harding ◽  
David Feindel ◽  
...  

A probe-based quantitative PCR (qPCR) protocol was developed for detection and evaluation of the wheat bacterial leaf streak pathogen Xanthomonas translucens pv. undulosa (Xtu). The protocol can also detect X. translucens pv. translucens (Xtt), but cannot differentiate the two pathovars. When tested on DNA from plant, non-target bacteria and culture of microorganisms from wheat seeds, the qPCR showed a high specificity. On purified Xtu DNA, the qPCR was more sensitive than a loop-mediated isothermal amplification (LAMP) assay. When DNA samples from a set of serial dilutions of Xtu cells were tested, the qPCR method could repeatedly generate quantification cycle (Cq) values from the dilutions containing 1,000 cells. Since 2 uL of the total of 50 uL DNA was used in one reaction, one qPCR reaction could detect the presence of the bacteria in samples containing as few as 40 bacterial cells. The qPCR could detect the bacteria from both infected seed and leaf tissues. For seed testing, a protocol for template preparation was standardized, which allowed one qPCR reaction to test DNA from the surface of one seed. Thus, the qPCR system could theoretically detect Xtu and/or Xtt in samples where the bacteria had an average concentration at or larger than 40 cells per seed.


Author(s):  
Lindsay Triplett ◽  
Ravikumar Patel

Abstract Xanthomonas vasicola pv. vasculorum (Xvv) is a bacterial pathogen that causes both bacterial leaf streak of maize and sugarcane gumming disease. After decades limited to South Africa, bacterial leaf streak of maize spread rapidly through maize-growing areas of Argentina, Brazil and the USA since 2014. The origin, method and biological underpinnings of this sudden spread are not well understood but are the subject of active research. Effective control methods remain elusive, but sanitation and crop debris management may limit the disease. Yield impact data are not yet available, but lesions may become severe enough to limit plant productivity in some varieties. The pathogen is not currently considered a quarantine threat by the USDA, EPPO or IPPC.


Author(s):  
Lindsay Triplett ◽  
Ravikumar Patel

Abstract Xanthomonas vasicola pv. vasculorum (Xvv) is a bacterial pathogen that causes both bacterial leaf streak of maize and sugarcane gumming disease. After decades limited to South Africa, bacterial leaf streak of maize spread rapidly through maize-growing areas of Argentina, Brazil and the USA since 2014. The origin, method and biological underpinnings of this sudden spread are not well understood but are the subject of active research. Effective control methods remain elusive, but sanitation and crop debris management may limit the disease. Yield impact data are not yet available, but lesions may become severe enough to limit plant productivity in some varieties. The pathogen is not currently considered a quarantine threat by the USDA, EPPO or IPPC. Taxonomic Tree Top of page Domain: Bacteria Phylum: Proteobacteria Class: Gammaproteobacteria Order: Xanthomonadales Family: Xanthomonadaceae Genus: Xanthomonas Species: Xanthomonas vasicola pv. vasculorum Notes on Taxonomy and Nomenclature Top of page The taxonomic nomenclature of the pathogen has undergone several changes and is still being resolved at the time of this report. The Xanthomonas clade causing.


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