Plant holobiont interactions mediated by the type <scp>VI</scp> secretion system and the membrane vesicles: promising tools for a greener agriculture

Acuña, José Manuel Borrero‐de; Bernal, Patricia

doi:10.1111/1462-2920.15457

Cited by 15 publications

(13 citation statements)

References 31 publications

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“…The KT2440 strain studied in this work represents a well-established biological control agent [46]. Importantly, this strain is the model organism employed to study the role of the T6SS as a potent molecular weapon to control plant pathogens [5,11,66].…”

Section: Discussionmentioning

confidence: 99%

Transcriptional organization and regulation of the Pseudomonas putida K1 type VI secretion system gene cluster

et al. 2023

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The type VI secretion system (T6SS) is an antimicrobial molecular weapon that is widespread in Proteobacteria and offers competitive advantages to T6SS-positive micro-organisms. Three T6SSs have recently been described in Pseudomonas putida KT2440 and it has been shown that one, K1-T6SS, is used to outcompete a wide range of phytopathogens, protecting plants from pathogen infections. Given the relevance of this system as a powerful and innovative mechanism of biological control, it is critical to understand the processes that govern its expression. Here, we experimentally defined two transcriptional units in the K1-T6SS cluster. One encodes the structural components of the system and is transcribed from two adjacent promoters. The other encodes two hypothetical proteins, the tip of the system and the associated adapters, and effectors and cognate immunity proteins, and it is also transcribed from two adjacent promoters. The four identified promoters contain the typical features of σ 70 -dependent promoters. We have studied the expression of the system under different conditions and in a number of mutants lacking global regulators. P. putida K1-T6SS expression is induced in the stationary phase, but its transcription does not depend on the stationary σ factor RpoS. In fact, the expression of the system is indirectly repressed by RpoS. Furthermore, it is also repressed by RpoN and the transcriptional regulator FleQ, an enhancer-binding protein typically acting in conjunction with RpoN. Importantly, expression of the K1-T6SS gene cluster is positively regulated by the GacS–GacA two-component regulatory system (TCS) and repressed by the RetS sensor kinase, which inhibits this TCS. Our findings identified a complex regulatory network that governs T6SS expression in general and P. putida K1-T6SS in particular, with implications for controlling and manipulating a bacterial agent that is highly relevant in biological control.

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Section: Discussionmentioning

confidence: 99%

Transcriptional organization and regulation of the Pseudomonas putida K1 type VI secretion system gene cluster

et al. 2023

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“…Previous, study revealed that this strain is able to help manage several plant diseases by producing antibiotics, competition with other pathogens for space and nutrients, and stimulation of host systemic resistance ( Riaz et al, 2022 ). This bacterial strain has a Type-VI Secretion System (T6SS) used to kill and eradicate plant pathogens and is vital in its bio-control portfolio ( Borrero de Acuña and Bernal, 2021 ). It was found promising against several destructive plant pathogens such as Fusarium oxysporum in tomato, Rhizoctonia solani in potato and Pectobacterium atrosepticum in potato, Sclerotinia sclerotiorum in lettuce and Ralstonia solanacearum in tomato ( Bernal Guzmán et al, 2017 ; Durán et al, 2021 ).…”

Section: Biological Controlmentioning

confidence: 99%

Neocosmospora rubicola, a stem rot disease in potato: Characterization, distribution and management

Riaz

Akhtar²,

Msimbira³

et al. 2022

Front. Microbiol.

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Potato (Solanum tuberosum L.) is one of the most important crops in maintaining global food security. Plant stand and yield are affected by production technology, climate, soil type, and biotic factors such as insects and diseases. Numerous fungal diseases including Neocosmospora rubicola, causing stem rot, are known to have negative effects on potato growth and yield quality. The pathogen is known to stunt growth and cause leaf yellowing with grayish-black stems. The infectivity of N. rubicola across a number of crops indicates the need to search for appropriate management approaches. Synthetic pesticides application is a major method to mitigate almost all potato diseases at this time. However, these pesticides significantly contribute to environmental damage and continuous use leads to pesticide resistance by pathogens. Consumers interest in organic products have influenced agronomists to shift toward the use of biologicals in controlling most pathogens, including N. rubicola. This review is an initial effort to carefully examine current and alternative approaches to control N. rubicola that are both environmentally safe and ecologically sound. Therefore, this review aims to draw attention to the N. rubicola distribution and symptomatology, and sustainable management strategies for potato stem rot disease. Applications of plant growth promoting bacteria (PGPB) as bioformulations with synthetic fertilizers have the potential to increase the tuber yield in both healthy and N. rubicola infested soils. Phosphorus and nitrogen applications along with the PGPB can improve plants uptake efficiency and reduce infestation of pathogen leading to increased yield. Therefore, to control N. rubicola infestation, with maximum tuber yield benefits, a pre-application of the biofertilizer is shown as a better option, based on the most recent studies. With the current limited information on the disease, precise screening of the available resistant potato cultivars, developing molecular markers for resistance genes against N. rubicola will assist to reduce spread and virulence of the pathogen.

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“…Pseudomonas putida, a Gram-negative bacterium, benefits crop plants by acting as a phosphate solubilizer and biocontrol agent (Sun et al, 2017;Takishita et al, 2021). The bacterium has a Type VI Secretion System (T6SS) to kill phytopathogens, which is important in its biocontrol portfolio (Borrero De Acuña and Bernal, 2021). It was found effective for a number of destructive plant pathogens like F. oxysporum in tomato, Rhizoctonia solani and Pectobacterium atrosepticum in potato and Sclerotinia sclerotiorum in lettuce (Bernal et al, 2017;Durán et al, 2021).…”

Section: Introductionmentioning

confidence: 99%

A Bacterial Consortium and Synthetic Fertilizer Based Biocontrol Approach Against Potato Rot Disease “Neocosmospora rubicola”

et al. 2022

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Conventional management of stem rot disease of potato, caused by Neocosmospora rubicola, through fungicide application is an environmentally unfavorable practice that calls for an alternative biocontrol approach. Plant growth-promoting bacteria (PGPB) are known to not only promote plant growth but also control diseases caused by various fungi. The study was designed to evaluate the potential of three strains of PGPB and synthetic fertilizer to manage stem rot of potatoes. In the first experiment, PGPB strains Azotobacter chroococcum, Azospirillum lipoferum, and Pseudomonas putida and their combinations were evaluated on PDA medium against N. rubicola using the dual culture technique. All three bacterial strains were found effective in reducing the radial growth of the fungus maximum up to 91%. In the second experiment, in the presence of half and full recommended doses of fertilizer nitrogen (N) and phosphorus (P), the potato growing medium was inoculated with N. rubicola alone, and with combinations of N. rubicola and PGPB strains (bacterial formulation; BF). N. rubicola increased stem and tuber rot, and decreased tuber weight by 11% compared to the control. On the other hand, sole inoculation with BF significantly increased tuber weight. In addition, a combined inoculation of N. rubicola and BF, or N. rubicola inoculation a week prior to BF inoculation did not affect tuber weight compared to control. However, inoculation of BF a week prior to N. rubicola, controlled rot symptoms and increased tuber weight by 32%. An increase in P application favored the PGPB strains in controlling rot in tubers. The interaction effect of fertilizer N with the inoculation combinations was non-significant; however, the main impact of N was to increase rot in tubers and decrease in potato stems. Hence a prerequisite application of PGPB formulation proved to be an effective tool against N. rubicola infestation in potatoes.

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Plant holobiont interactions mediated by the type VI secretion system and the membrane vesicles: promising tools for a greener agriculture

Cited by 15 publications

References 31 publications

Transcriptional organization and regulation of the Pseudomonas putida K1 type VI secretion system gene cluster

Transcriptional organization and regulation of the Pseudomonas putida K1 type VI secretion system gene cluster

Neocosmospora rubicola, a stem rot disease in potato: Characterization, distribution and management

A Bacterial Consortium and Synthetic Fertilizer Based Biocontrol Approach Against Potato Rot Disease “Neocosmospora rubicola”

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