scholarly journals Streptomyces-Induced Resistance Against Oak Powdery Mildew Involves Host Plant Responses in Defense, Photosynthesis, and Secondary Metabolism Pathways

2014 ◽  
Vol 27 (9) ◽  
pp. 891-900 ◽  
Author(s):  
Florence Kurth ◽  
Sarah Mailänder ◽  
Markus Bönn ◽  
Lasse Feldhahn ◽  
Sylvie Herrmann ◽  
...  

Rhizobacteria are known to induce defense responses in plants without causing disease symptoms, resulting in increased resistance to plant pathogens. This study investigated how Streptomyces sp. strain AcH 505 suppressed oak powdery mildew infection in pedunculate oak, by analyzing RNA-Seq data from singly- and co-inoculated oaks. We found that this Streptomyces strain elicited a systemic defense response in oak that was, in part, enhanced upon pathogen challenge. In addition to induction of the jasmonic acid/ethylene–dependent pathway, the RNA-Seq data suggests the participation of the salicylic acid–dependent pathway. Transcripts related to tryptophan, phenylalanine, and phenylpropanoid biosynthesis were enriched and phenylalanine ammonia lyase activity increased, indicating that priming by Streptomyces spp. in pedunculate oak shares some determinants with the Pseudomonas-Arabidopsis system. Photosynthesis-related transcripts were depleted in response to powdery mildew infection, but AcH 505 alleviated this inhibition, which suggested there is a fitness benefit for primed plants upon pathogen challenge. This study offers novel insights into the mechanisms of priming by actinobacteria and highlights their capacity to activate plant defense responses in the absence of pathogen challenge.

2017 ◽  
Vol 30 (10) ◽  
pp. 842-851 ◽  
Author(s):  
Madhu Kappagantu ◽  
Jeff M. Bullock ◽  
Mark E. Nelson ◽  
Kenneth C. Eastwell

Viroids are the smallest known plant pathogens that exploit host systems for their replication and cause diseases in many hosts. In this study, the host response of hop plants to Hop stunt viroid (HSVd) infection was studied through transcriptome analysis. RNA sequence analysis of hop leaves infected with HSVd revealed dynamic changes in hop gene expression. Defense-related genes and genes involved in lipid and terpenoid metabolism are the major categories that showed differential expression due to HSVd infection. Additionally, the effect of HSVd on development of hop powdery mildew (Podospheara macularis) (HPM) was studied. Transcriptome analysis followed by quantitative reverse transcription-polymerase chain reaction analysis showed that transcript levels of pathogenesis-related (PR) genes such as PR protein 1, chitinase, and thaumatin-like protein genes are induced in leaves infected with HPM alone. The response in these genes to HPM is significantly down-regulated in leaves with HSVd-HPM mixed infection. These results confirm that HSVd alters host metabolism, physiology, and plant defense responses. Nevertheless, in detached leaf assays, HPM consistently expanded faster on HSVd-negative leaves relative to HSVd-positive leaves. Although HSVd infection suppresses elements associated with the host immunity response, infection by HSVd is antagonistic to HPM infection of hops.


PeerJ ◽  
2016 ◽  
Vol 4 ◽  
pp. e1991 ◽  
Author(s):  
Yanping Li ◽  
Shilin Tian ◽  
Xiaojun Yang ◽  
Xin Wang ◽  
Yuhai Guo ◽  
...  

Physcion and chrysophanol induce defense responses against powdery mildew in cucumbers. The combination of these two compounds has synergistic interaction against the disease. We performed RNA-seq on cucumber leaf samples treated with physcion and chrysophanol alone and with their combination. We generated 17.6 Gb of high-quality sequencing data (∼2 Gb per sample) and catalogued the expressions profiles of 12,293 annotated cucumber genes in each sample. We identified numerous differentially expressed genes that exhibited distinct expression patterns among the three treatments. The gene expression patterns of the Chr and Phy treatments were more similar to each other than to the Phy × Chr treatment. The Phy × Chr treatment induced the highest number of differentially expressed genes. This dramatic transcriptional change after Phy × Chr treatment leaves reflects that physcion combined with chrysophanol treatment was most closely associated with induction of disease resistance. The analysis showed that the combination treatment caused expression changes of numerous defense-related genes. These genes have known or potential roles in structural, chemical and signaling defense responses and were enriched in functional gene categories potentially responsible for cucumber resistance. These results clearly demonstrated that disease resistance in cucumber leaves was significantly influenced by the combined physcion and chrysophanol treatment. Thus, physcion and chrysophanol are appealing candidates for further investigation of the gene expression and associated regulatory mechanisms related to the defense response.


2017 ◽  
Vol 1 (1) ◽  
pp. 40-54 ◽  
Author(s):  
Shridhar Jambagi ◽  
Shridhar Jambagi ◽  
Jim M. Dunwell ◽  
Jim M. Dunwell

Strawberry powdery mildew, caused by Podosphaeraaphanis is a major fungal disease that affects strawberry yield and quality. In the model plant species Arabidopsis and the crop plants barley, tomato and pea, the Mildew resistance locus O (MLO) proteins have been found to be required for powdery mildew susceptibility. The present study, based on the sequence of a wild plum (Prunus americana) MLO protein, identified 16 MLO genes within the genome of woodland strawberry, Fragaria vesca and examined their expression pattern in response to powdery mildew infection in three diploid strawberry cultivars. Phylogenetic analysis showed that the FvMLO genes can be classified into six clades. Four FvMLO genes were grouped into clade III, which comprises MLO genes from Arabidopsis, tomato and grapevine that mediate powdery mildew susceptibility. A RNA-seq analysis of two diploid strawberry cultivars, F. vescassp. vesca accession Hawaii 4 (HW) and F. vesca f. semperflorens line “Yellow Wonder 5AF7” (YW) at 1 d (1 DAI) and 8 d (8 DAI) after infection showed the expression of 12 out of the 16 FvMLO genes. The comparison of Fragments Per Kilobase of transcript per Million mapped reads (FPKM values) detected by RNA-seq and expression values of qRT-PCR for FvMLO genes showed substantial agreement. The FvMLO3 gene, which was grouped in clade III and orthologous to the Arabidopsis,tomato and grapevine genes, was highly expressed in YW compared to other FvMLO genes across varieties. The results showed that FvMLO genes can be used as potential candidates to engineer powdery mildew resistance in strawberry based on MLO suppression or genome editing.


2019 ◽  
Author(s):  
Cheng Hong ◽  
Kong Wei-ping ◽  
Lü Jun-Feng

AbstractMelon (Cucumis melo L.) is wildly planted in the world and China is a major producer of muskmelon. Powdery mildew is one of the most common fungal diseases in the world and this disease frequently affects melon (Cucumis melo L.) and due to the reduction of melon yield. In this study, one material GanTianmi with thin peel and another material XueLianHua with thick peel were selected. After inoculating the powdery mildew, both materials were used to do the RNA-Seq. In total two RNA-seq libraries were constructed and sequenced separately. The reads per kilobase per Million mapped reads (RPKM) values of all the genes in the two materials were calculated and there were 13828 genes were expressed in the material G and 13944 genes were expressed in the material S (RPKM>1). The differentially expression gene (DEG) analysis result suggested that total 769 the DEGs between the two materials were identified. All the DEGs were annotated with several database and the transcript factors (TFs) that related to disease resistance such as MYB, ERF and WRKY among the DEGs were also identified. This research could not only provide the information about understanding the mechanism of powdery mildew infection but also help researchers breed the varieties with powdery mildew resistance.


2013 ◽  
Vol 49 (Special Issue) ◽  
pp. S41-S54 ◽  
Author(s):  
L. Kubienová ◽  
M. Sedlářová ◽  
A. Vítečková-Wünschová ◽  
J. Piterková ◽  
L. Luhová ◽  
...  

Changes in Hsp70 gene expression and protein level were studied in three Solanum spp. genotypes in response to short-term high and low temperatures and to infection by powdery mildew. Development of Oidium neolycopersici was compared on plant leaves and leaf discs with regard to the influence of temperature. Heat and especially cold pre-treatment of host tissues inhibited pathogenesis and decreased chlorophyll concentration. Exposure to heat increased Hsp70 (70 kDa heat shock proteins) content in all three genotypes of Solanum spp., whereas the infection induced the accumulation of Hsp70 only in susceptible S. lycopersicum. These results are in accordance with the suggested role of Hsp70 chaperons in plant responses to metabolic pathway disturbances triggered by pathogen challenge. 


2004 ◽  
Vol 85 (1) ◽  
pp. 33-37 ◽  
Author(s):  
Magali Merkx-Jacques ◽  
Jacqueline C. Bede

Abstract Plants exhibit remarkable plasticity in their ability to differentiate between herbivorous insect species and subtly adjust their defense responses to target distinct pests. One key mechanism used by plants to recognize herbivorous caterpillars is elicitors present in their oral secretions; however, these elicitors not only cause the induction of plant defenses but recent evidence suggests that they may also suppress plant responses. The absence of “expected changes” in induced defense responses of insect-infested plants has been attributed to hydrogen peroxide produced by caterpillar salivary glucose oxidase (GOX). Activity of this enzyme is variable among caterpillar species; it was detected in two generalist caterpillars, the beet armyworm (Spodoptera exigua) and the bertha armyworm (Mamestra configurata), but not in other generalist or specialist caterpillar species tested. In the beet armyworm, GOX activity fluctuated over larval development with high activity associated with the salivary glands of fourth instars. Larval salivary GOX activity of the beet armyworm and the bertha armyworm was observed to be significantly higher in caterpillars reared on artificial diet as compared with those reared on Medicago truncatula plants. This implies that a factor in the diet is involved in the regulation of caterpillar salivary enzyme activity. Therefore, plant diet may be regulating caterpillar oral elicitors that are involved in the regulation of plant defense responses: our goal is to understand these two processes.


1975 ◽  
Vol 53 (22) ◽  
pp. 2589-2597 ◽  
Author(s):  
H. H. Edwards

M1-a-mediated resistance in barley to invasion by the CR3 race of Erysiphe graminis f. sp. hordei does not occur in every host cell with the same speed and severity. In some cells ultrastructural changes within the host cell as a result of resistance will occur within 24 h after inoculation, whereas in other cells these changes may take up to 72 h. In some cells the ultrastructural changes are so drastic that they give the appearance of a hypersensitive death of the host cell, whereas in other cells the changes are very slight. In any case, at the end of these changes the fungus ceases growth. The ultrastructural changes occur in penetrated host epidermal cells as well as non-infected adjacent epidermal and mesophyll cells.The following ultrastructural changes have been observed: (1) an electron-dense material which occurs either free in the vacuole or adhering to the tonoplast (the material is granular or in large clumps); (2) an increased electron density of the host cytoplasm and nucleus; (3) a breakdown of the tonoplast so that the cytoplasmic constituents become dispersed throughout the cell lumen; and (4) the deposition of papillar-like material in areas other than the penetration site. The first three changes take place within the host cell protoplasts and are directly attributable to the gene M1-a. These changes are typical of stress or incompatibility responses and thus M1-a appears to trigger a generalized incompatibility response in the presence of race CR3. The papillar-like material occurs outside the host cell protoplast in the same manner as the papilla and probably is not directly attributable to M1-a.


Plant Science ◽  
2021 ◽  
pp. 111034
Author(s):  
Wenbo Chai ◽  
Nannan Song ◽  
Anqi Su ◽  
Jun Wang ◽  
Weina Si ◽  
...  

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