Microbes that provide benefit to plants are termed as plant growth-promoting bacteria (PGPB) and can facilitate plant growth and protect them from pathogenic microorganisms by several different mechanisms. PGPR can stimulate plant growth promoting traits and induce plant health by providing IAA synthesis, siderophore production, phosphate solubilization activity, ammonia production, and antibiotic production: because of these mechanisms beneficial microbes can protect host plants from several biotic and abiotic stresses. Plant growth-promoting bacterial endophytes employ similar plant growth promotion mechanisms to those used by rhizospheric PGPB. A set of beneficial PGPR were evaluated for their in vitro antimicrobial activity on various phytopathogenic bacteria and fungi. We identified plant growth-promoting endophytes within the bacterial groups as part of the core bacterial consortium. The Streptomyces sp. strain SA51 and Pseudomonas sp. strain PT65 used in the present study were extensively characterized to evaluate their in vitro plant growth promoting (PGP) traits and their biocontrol activity. Here, we characterized both the strains SA51 and PT65 for their colonization ability, plant growth promotion and protection against tomato spot disease caused by Xanthomonas vesicatoria on tomato (Solanum lycopersicum) as model plant. In this study, direct inhibitory action against X. vesicatoria by the bacterized tomato plants showed a significantly good plant growth, as compared to unbacterized controls. Protection against X. vesicatoria by the bacterized tomato plants was confirmed in the greenhouse: disease was reduced by approximately 96%. Additionally, plants bacterized by strain SA51 showed significant plant growth, particularly in aerial parts as compared to un-bacterized controls. Finally, benefit was seen in inoculated healthy plants in terms of a significant increase in dry weight and length of roots and shoots, as compared to the uninoculated controls. A GFP mutant of strain SA51 was produced to study its endophytic colonisation in tomato plants: results confirmed that SA51 was able to efficiently colonise tomato endophytically, from the roots to the leaves. Field experiments confirmed the ability of strain SA51 to act as plant growth promoting agent: such promoting activity was also reflected into an increase of fruit production by approximately 7%. Plant growth promotion is a multigenic process under the influence of many factors; therefore, an understanding of these processes and the functions regulated may have profound implications. The present study reports differential gene expression analysis of Grapevine leaves inoculated with a beneficial microbial consortium that resulted in significant increase in growth traits in terms of biochemical and biocontrol as compared with non-inoculated control. The gene expression changes, represented by different time points hours post inoculation (hpi) have been studied to gain insight into various genes responsible for pathogen related (PR) proteins, lytic enzymes, growth hormones and to maintain cell wall integrity assisted plant growth promotion grapevine leaves. It was observed that the microbial consortium profusely induced the upregulation of grapevine genes involved in maintenance of biocontrol and plant growth promotion activity. Almost all the genes were downregulated initially after 0 hpi and 2 hpi, but later from 4 hpi genes like ACC, CHS, PAL & PER were significantly upregulated. Particularly, PR11 and PR12 genes were significantly upregulated after 4 hpi. Summarising, we were able to confirm the ability of single beneficial microbes and a microbial consortium to act as promoting factor for plant growth and health; this study was done in vitro and in planta.

I microrganismi che forniscono benefici alle piante promuovono la loro crescita e le proteggono dai patogeni attraverso diversi meccanismi. Tali meccanismi sono la sintesi di IAA, produzione di siderofori, attività di solubilizzazione dei fosfati, produzione di ammoniaca e produzione di antibiotici. meccanismi Pertanto essi sono in grado di proteggere le piante ospiti da numerosi stress biotici e abiotici. Gli endofiti batterici che promuovono la crescita delle piante impiegano meccanismi di promozione della crescita delle piante simili a quelli utilizzati dai rizobatteri. Una serie di microrganismi benefici sono stati valutati per la loro attività antimicrobica in vitro su vari batteri e funghi fitopatogeni. Abbiamo identificato gli endofiti che promuovono la crescita delle piante all'interno dei gruppi batterici come parte del consorzio batterico. Streptomyces sp. ceppo SA51 e Pseudomonas sp. il ceppo PT65 utilizzato nel presente studio sono stati ampiamente caratterizzati per valutare la loro attività di promozione della crescita delle piante in vitro e del biocontrollo. Qui, abbiamo caratterizzato sia i ceppi SA51 che PT65 per la loro capacità di colonizzazione, promozione della crescita delle piante e protezione contro le malattie dei punti del pomodoro causate da Xanthomonas vesicatoria sul pomodoro (Solanum lycopersicum) come pianta modello. In questo studio, l'azione inibitoria diretta contro X. vesicatoria da parte delle piante di pomodoro batterizzate ha mostrato una crescita della pianta significativamente migliore rispetto al controllo. La protezione contro X. vesicatoria in piante di pomodoro batterizzate è stata confermata in serra: la malattia è stata ridotta di circa il 96%. Inoltre, le piante batterizzate dal ceppo SA51 hanno mostrato una crescita significativamente migliore rispetto ai controlli non batterizzati. Infine, è stato riscontrato un beneficio in piante sane inoculate in termini di un aumento significativo del peso secco e della lunghezza di radici e germogli, rispetto ai controlli non inoculati. Un mutante GFP del ceppo SA51 è stato prodotto per studiare la sua colonizzazione endofita nelle piante di pomodoro: i risultati hanno confermato che SA51 è in grado di colonizzare in modo efficiente il pomodoro endofiticamente, dalle radici alle foglie. Gli esperimenti sul campo hanno confermato la capacità del ceppo SA51 di agire come agente di promozione della crescita delle piante: tale attività di promozione si è anche riflessa in un aumento della produzione di frutta di circa il 7%. La promozione della crescita delle piante è un processo multigenico sotto l'influenza di molti fattori; pertanto, la comprensione di questi processi e delle funzioni regolate può avere profonde implicazioni. Il presente studio riporta l'analisi dell'espressione genica differenziale in vite inoculate con un consorzio microbico . I cambiamenti di espressione genica, a diverse ore dopo l'inoculazione (hpi) sono stati studiati per ottenere informazioni su vari geni codificanti proteine di patogenesi (PR), enzimi litici, ormoni della crescita e per mantenere l'integrità della parete cellulare favorendo la promozione della crescita delle piante della vite le foglie. È stato dimostrato che i consorzi microbici hanno indotto la sovraespressione digeni della vite coinvolti nel mantenimento del biocontrollo e nell'attività di promozione della crescita delle piante. Quasi tutti i geni sono stati sotto-regolati inizialmente dopo 0 hpi e 2 hpi, ma in seguito da 4 geni hpi come ACC, CHS, PAL e PER sono stati significativamente sovraregolati. In particolare, i geni PR11 e PR12 hanno significativamente sovraregolato dopo 4 hpi. Pertanto è stata confermata l’attività benefica in vitro e in planta di singoli microrganismi e di loro consorzi.

Agricoltura simbiotica: aumentare le conoscenze sulle modalità di azione dei microrganismi benefici / Sai Shivakrishnaprasad Vurukonda , 2020 Mar 19. 32. ciclo, Anno Accademico 2018/2019.

Agricoltura simbiotica: aumentare le conoscenze sulle modalità di azione dei microrganismi benefici.

VURUKONDA, SAI SHIVAKRISHNAPRASAD
2020

Abstract

Microbes that provide benefit to plants are termed as plant growth-promoting bacteria (PGPB) and can facilitate plant growth and protect them from pathogenic microorganisms by several different mechanisms. PGPR can stimulate plant growth promoting traits and induce plant health by providing IAA synthesis, siderophore production, phosphate solubilization activity, ammonia production, and antibiotic production: because of these mechanisms beneficial microbes can protect host plants from several biotic and abiotic stresses. Plant growth-promoting bacterial endophytes employ similar plant growth promotion mechanisms to those used by rhizospheric PGPB. A set of beneficial PGPR were evaluated for their in vitro antimicrobial activity on various phytopathogenic bacteria and fungi. We identified plant growth-promoting endophytes within the bacterial groups as part of the core bacterial consortium. The Streptomyces sp. strain SA51 and Pseudomonas sp. strain PT65 used in the present study were extensively characterized to evaluate their in vitro plant growth promoting (PGP) traits and their biocontrol activity. Here, we characterized both the strains SA51 and PT65 for their colonization ability, plant growth promotion and protection against tomato spot disease caused by Xanthomonas vesicatoria on tomato (Solanum lycopersicum) as model plant. In this study, direct inhibitory action against X. vesicatoria by the bacterized tomato plants showed a significantly good plant growth, as compared to unbacterized controls. Protection against X. vesicatoria by the bacterized tomato plants was confirmed in the greenhouse: disease was reduced by approximately 96%. Additionally, plants bacterized by strain SA51 showed significant plant growth, particularly in aerial parts as compared to un-bacterized controls. Finally, benefit was seen in inoculated healthy plants in terms of a significant increase in dry weight and length of roots and shoots, as compared to the uninoculated controls. A GFP mutant of strain SA51 was produced to study its endophytic colonisation in tomato plants: results confirmed that SA51 was able to efficiently colonise tomato endophytically, from the roots to the leaves. Field experiments confirmed the ability of strain SA51 to act as plant growth promoting agent: such promoting activity was also reflected into an increase of fruit production by approximately 7%. Plant growth promotion is a multigenic process under the influence of many factors; therefore, an understanding of these processes and the functions regulated may have profound implications. The present study reports differential gene expression analysis of Grapevine leaves inoculated with a beneficial microbial consortium that resulted in significant increase in growth traits in terms of biochemical and biocontrol as compared with non-inoculated control. The gene expression changes, represented by different time points hours post inoculation (hpi) have been studied to gain insight into various genes responsible for pathogen related (PR) proteins, lytic enzymes, growth hormones and to maintain cell wall integrity assisted plant growth promotion grapevine leaves. It was observed that the microbial consortium profusely induced the upregulation of grapevine genes involved in maintenance of biocontrol and plant growth promotion activity. Almost all the genes were downregulated initially after 0 hpi and 2 hpi, but later from 4 hpi genes like ACC, CHS, PAL & PER were significantly upregulated. Particularly, PR11 and PR12 genes were significantly upregulated after 4 hpi. Summarising, we were able to confirm the ability of single beneficial microbes and a microbial consortium to act as promoting factor for plant growth and health; this study was done in vitro and in planta.
Symbiotic Agriculture: Increasing Knowledge on the Mode of Action of Beneficial Microorganisms.
19-mar-2020
STEFANI, Emilio
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