scholarly journals Diversity Analysis of Endophytic Bacterial Community in Two Citrus Cultivars With Different Resistance to Citrus Canker

Author(s):  
Bing Liu ◽  
Jiahao Lai ◽  
Simeng Wu ◽  
Junxi Jiang ◽  
Weigang Kuang

Abstract The selective infection of Xanthomonas citri pv. citri to citrus cultivars is universally known, but it is not clarified whether there is a relationship between endophytic bacteria and the resistance of host variety to canker disease. In order to explore the relationship, Satsuma mandarin and Newhall navel orange were collected respectively as samples of resistant or susceptible cultivars to citrus canker disease, and endophytic bacterial community of two citrus cultivars were analyzed by using a next-generation, Illumina-based sequencing approach. Simultaneously, the seasonal dynamics of endophytic bacterial community and dominant genera were analyzed. The results showed that there were four dominant groups including Proteobacteria, Firmicutes, Actinobacteria and Bacteroidetes in all samples at phylum level. Endophytic bacteria were the most abundant in spring samples, then in summer and autumn samples. There were some differences between endophytic bacterial community of resistant citrus and that of susceptible citrus to canker disease, and the endophytic bacteria of Satsuma mandarin are more abundant than that of Newhall navel orange. According to the analysis of dominant bacteria in two citrus cultivars, it was found that some endophytic bacteria with antagonistic characteristics existed universally in all samples, although the dominant bacteria in different seasonal sample were different. However, in Newhall navel orange of susceptible citrus to canker disease, there were not only some bacteria against Xanthomonas citri pv. citri, but also some cooperative bacteria of canker occurrence like Stenotrophomonas.

2021 ◽  
Vol 9 (6) ◽  
pp. 1176
Author(s):  
Simone Cristina Picchi ◽  
Laís Moreira Granato ◽  
Maria Júlia Festa Franzini ◽  
Maxuel Oliveira Andrade ◽  
Marco Aurélio Takita ◽  
...  

Xanthomonas citri subsp. citri (X. citri) is a plant pathogenic bacterium causing citrus canker disease. The xanA gene encodes a phosphoglucomutase/phosphomannomutase protein that is a key enzyme required for the synthesis of lipopolysaccharides and exopolysaccharides in Xanthomonads. In this work, firstly we isolated a xanA transposon mutant (xanA::Tn5) and analyzed its phenotypes as biofilm formation, xanthan gum production, and pathogenesis on the sweet orange host. Moreover, to confirm the xanA role in the impaired phenotypes we further produced a non-polar deletion mutant (ΔxanA) and performed the complementation of both xanA mutants. In addition, we analyzed the percentages of the xanthan gum monosaccharides produced by X. citri wild-type and xanA mutant. The mutant strain had higher ratios of mannose, galactose, and xylose and lower ratios of rhamnose, glucuronic acid, and glucose than the wild-type strain. Such changes in the saccharide composition led to the reduction of xanthan yield in the xanA deficient strain, affecting also other important features in X. citri, such as biofilm formation and sliding motility. Moreover, we showed that xanA::Tn5 caused no symptoms on host leaves after spraying, a method that mimetics the natural infection condition. These results suggest that xanA plays an important role in the epiphytical stage on the leaves that is essential for the successful interaction with the host, including adaptive advantage for bacterial X. citri survival and host invasion, which culminates in pathogenicity.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Simone Cristina Picchi ◽  
Mariana de Souza e Silva ◽  
Luiz Leonardo Saldanha ◽  
Henrique Ferreira ◽  
Marco Aurélio Takita ◽  
...  

AbstractN-Acetylcysteine (NAC) is an antioxidant, anti-adhesive, and antimicrobial compound. Even though there is much information regarding the role of NAC as an antioxidant and anti-adhesive agent, little is known about its antimicrobial activity. In order to assess its mode of action in bacterial cells, we investigated the metabolic responses triggered by NAC at neutral pH. As a model organism, we chose the Gram-negative plant pathogen Xanthomonas citri subsp. citri (X. citri), the causal agent of citrus canker disease, due to the potential use of NAC as a sustainable molecule against phytopathogens dissemination in citrus cultivated areas. In presence of NAC, cell proliferation was affected after 4 h, but damages to the cell membrane were observed only after 24 h. Targeted metabolite profiling analysis using GC–MS/TOF unravelled that NAC seems to be metabolized by the cells affecting cysteine metabolism. Intriguingly, glutamine, a marker for nitrogen status, was not detected among the cells treated with NAC. The absence of glutamine was followed by a decrease in the levels of the majority of the proteinogenic amino acids, suggesting that the reduced availability of amino acids affect protein synthesis and consequently cell proliferation.


2019 ◽  
Vol 35 (5) ◽  
pp. 486-497 ◽  
Author(s):  
Md. Nurul Islam ◽  
Md. Sarafat Ali ◽  
Seong-Jin Choi ◽  
Jae-Wook Hyun ◽  
Kwang-Hyun Baek

2019 ◽  
Vol 7 (2) ◽  
pp. 47 ◽  
Author(s):  
Zhen-Shan Deng ◽  
Bao-Cheng Zhang ◽  
Xiang-Ying Qi ◽  
Zhi-Hong Sun ◽  
Xiao-Long He ◽  
...  

Pennisetum sinese, a source of bio-energy with high biomass production, is a species that contains high crude protein and will be useful for solving the shortage of forage grass after the implementation of “Green for Grain” project in the Loess plateau of Northern Shaanxi in 1999. Plants may receive benefits from endophytic bacteria, such as the enhancement of plant growth or the reduction of plant stress. However, the composition of the endophytic bacterial community associated with the roots of P. sinese is poorly elucidated. In this study, P. sinese from five different samples (Shaanxi province, SX; Fujian province, FJ; the Xinjiang Uyghur autonomous prefecture, XJ and Inner Mongolia, including sand (NS) and saline-alkali land (NY), China) were investigated by high-throughput next-generation sequencing of the 16S rDNA V3-V4 hypervariable region of endophytic bacteria. A total of 313,044 effective sequences were obtained by sequencing five different samples, and 957 effective operational taxonomic units (OTUs) were yielded at 97% identity. The phylum Proteobacteria, the classes Gammaproteobacteria and Alphaproteobacteria, and the genera Pantoea, Pseudomonas, Burkholderia, Arthrobacter, Psychrobacter, and Neokomagataea were significantly dominant in the five samples. In addition, our results demonstrated that the Shaanxi province (SX) sample had the highest Shannon index values (3.795). We found that the SX (308.097) and NS (126.240) samples had the highest and lowest Chao1 richness estimator (Chao1) values, respectively. Venn graphs indicated that the five samples shared 39 common OTUs. Moreover, according to results of the canonical correlation analysis (CCA), soil total carbon, total nitrogen, effective phosphorus, and pH were the major contributing factors to the difference in the overall composition of the bacteria community in this study. Our data provide insights into the endophytic bacteria community composition and structure of roots associated with P. sinese. These results might be useful for growth promotion in different samples, and some of the strains may have the potential to improve plant production in future studies.


2021 ◽  
Author(s):  
Hongfei Wang ◽  
Manik Prabhu Narsing Rao ◽  
Yanli Gao ◽  
Xinyang Li ◽  
Rui Gao ◽  
...  

Abstract Background: The seed dimorphism was thought to be a bet-hedging strategy, which assists plants to survive in the disturbed environment and has been widely studied for their ecological adaptation mechanism. Many studies showed that seed-associated microorganisms play an important role in enhancing plant fitness, but information regarding endophytic bacteria associated with dimorphic seeds is limited. This study explores the influence of seed coat structure and seed phytochemical properties on the community composition and diversity of endophytic bacteria of dimorphic seeds of Suaeda glauca. In the present study, we firstly used 16S rRNA high-throughput gene sequencing method to compare the bacterial diversity and community composition between brown and black seeds of Suaeda glauca. Results: A significant difference was observed in seed coat structure and phytochemical properties between brown and black seeds of S. glauca. Total 9 phyla, 13 classes, 31 orders, 53 families, 102 genera were identified in the dimorphic seeds. The dominant phyla were Proteobacteria, Firmicutes, and Actinobacteria. The results showed that seed dimorphism had little impact on the diversity and richness of endophytic bacterial communities but significantly differs in the relative abundance of the bacterial community between brown and black seeds. At the phylum level, Actinobacteria tend to be enriched significantly in brown seeds. At the genus level, Rhodococcus, Ralstonia, Pelomonas and Bradyrhizobium tend to be enriched significantly in brown seeds, while Marinilactibacillus was mainly found in black seeds. Besides, brown seeds harbored a large number of bacteria with plant-growth-promoting traits, whereas black seeds presented bacteria with enzyme activities (i.e. pectinase, cellulolytic and xylanolytic activities). Conclusion: The endophytic bacterial community compositions were significantly different between dimorphic seeds of Suaeda glauca, and play an important role in the ecological adaptation of dimorphic seeds by performing different bacterial function roles. The endophytic bacterial communities of the dimorphic seeds might be influenced mainly by the seed coat structure and partly by seed phytochemical characteristics. These findings provide valuable information for better understanding of the ecological adaptation strategy of dimorphic seeds in the disturbed environment.


2019 ◽  
Vol 201 (20) ◽  
Author(s):  
Laís Moreira Granato ◽  
Simone Cristina Picchi ◽  
Maxuel de Oliveira Andrade ◽  
Paula Maria Moreira Martins ◽  
Marco Aurélio Takita ◽  
...  

ABSTRACT Xanthomonas citri subsp. citri causes citrus canker disease worldwide in most commercial varieties of citrus. Its transmission occurs mainly by wind-driven rain. Once X. citri reaches a leaf, it can epiphytically survive by forming a biofilm, which enhances the persistence of the bacteria under different environmental stresses and plays an important role in the early stages of host infection. Therefore, the study of genes involved in biofilm formation has been an important step toward understanding the bacterial strategy for survival in and infection of host plants. In this work, we show that the ecnAB toxin-antitoxin (TA) system, which was previously identified only in human bacterial pathogens, is conserved in many Xanthomonas spp. We further show that in X. citri, ecnA is involved in important processes, such as biofilm formation, exopolysaccharide (EPS) production, and motility. In addition, we show that ecnA plays a role in X. citri survival and virulence in host plants. Thus, this mechanism represents an important bacterial strategy for survival under stress conditions. IMPORTANCE Very little is known about TA systems in phytopathogenic bacteria. ecnAB, in particular, has only been studied in bacterial human pathogens. Here, we showed that it is present in a wide range of Xanthomonas sp. phytopathogens; moreover, this is the first work to investigate the functional role of this TA system in Xanthomonas citri biology, suggesting an important new role in adaptation and survival with implications for bacterial pathogenicity.


Nematology ◽  
2021 ◽  
pp. 1-17
Author(s):  
Wei Lu ◽  
Xiao-Jia Zhao ◽  
Jia-Jin Tan

Summary Pine wilt disease (PWD) is a devastating pine disease caused by Bursaphelenchus xylophilus and its main host in China is Pinus massoniana. The relationship between endophytic bacteria and disease resistance in P. massoniana remains unclear. In this paper, the leaves, roots, stems and treetops of different disease-resistant P. massoniana were studied as the research objective and Illumina MiSeq sequencing was used to analyse whether there were significant differences in the composition and diversity of endophytic bacterial communities between different disease-resistant P. massoniana. The results showed that at the genus level there were no obvious differences in the composition of the endophytic bacterial community of different disease-resistant P. massoniana in the leaves, but there were obvious differences in the roots, stems and treetops. The richness and diversity of endophytic bacteria in P. massoniana had no significant impact on its disease resistance, whilst the structure of endophytic bacterial community in stems and treetops may be related to its disease resistance.


2007 ◽  
Vol 73 (22) ◽  
pp. 7259-7267 ◽  
Author(s):  
Rodrigo Mendes ◽  
Aline A. Pizzirani-Kleiner ◽  
Welington L. Araujo ◽  
Jos M. Raaijmakers

ABSTRACT Bacteria were isolated from the rhizosphere and from inside the roots and stems of sugarcane plants grown in the field in Brazil. Endophytic bacteria were found in both the roots and the stems of sugarcane plants, with a significantly higher density in the roots. Many of the cultivated endophytic bacteria were shown to produce the plant growth hormone indoleacetic acid, and this trait was more frequently found among bacteria from the stem. 16S rRNA gene sequence analysis revealed that the selected isolates of the endophytic bacterial community of sugarcane belong to the genera of Burkholderia, Pantoea, Pseudomonas, and Microbacterium. Bacterial isolates belonging to the genus Burkholderia were the most predominant among the endophytic bacteria. Many of the Burkholderia isolates produced the antifungal metabolite pyrrolnitrin, and all were able to grow at 37°C. Phylogenetic analyses of the 16S rRNA gene and recA gene sequences indicated that the endophytic Burkholderia isolates from sugarcane are closely related to clinical isolates of the Burkholderia cepacia complex and clustered with B. cenocepacia (gv. III) isolates from cystic fibrosis patients. These results suggest that isolates of the B. cepacia complex are an integral part of the endophytic bacterial community of sugarcane in Brazil and reinforce the hypothesis that plant-associated environments may act as a niche for putative opportunistic human pathogenic bacteria.


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