Data di Pubblicazione:
2021
Citazione:
BIOCONTROL STRATEGIES AGAINST PLANT PATHOGENS / G.i.r. Shahzad ; tutor: P. Casati ; coordinatore: D. Bassi. Dipartimento di Scienze Agrarie e Ambientali - Produzione, Territorio, Agroenergia, 2021 Jun 14. 33. ciclo, Anno Accademico 2020.
Abstract:
It is a known fact that the whole agriculture system is suffering from the diseases caused by plant pathogens, affecting negatively the crop yield production, food security, biodiversity, agricultural ecosystem and hence agricultural economy. In many countries, the containment strategies of plant pathogens are still depending on chemical pesticides that cause adverse effects in the long term. According to the implementations reinforced by European council 2009/128/EC, biocontrol strategies are considered as the most profound and integrated approach for sustainable disease management. Defining biocontrol in terms of plant pathology, it is the purposeful utilization of beneficial microbes, or its molecules, to suppress phytopathogens’ ability to colonize or induce symptoms in the host. In spite of their lesser shelf-life and unreliability as compared to conventional pesticides, their targeted biological interaction with the phytopathogens reduces the possibility of affecting non-target organisms, environment and the development of resistance in the pathogen.
In this context, exploitation of bacterial endophytes has gained much attention during the past decades. Endophytic plant growth promoting bacteria (ePGPBs) mediate their biocontrol efficacy by targeting species through a multitude of direct or indirect biological interactions, often employing both modes of action, such as plant growth promotion, host’s resistance induction, allelochemicals secretion, and nutrients and niche competition. Another strategy that has gained popularity is the exogenous application of double stranded RNA (dsRNA), which is considered as the key trigger molecule of RNA interreference (RNAi), a post-transcriptional gene silencing mechanism, and has been shown to provide protection without the need for integration of dsRNA-expressing constructs as transgenes.
In the present doctoral thesis, the above-mentioned biocontrol strategies were adapted, utilizing “ePGPBs as microbial inoculants” and “exogenously applied dsRNA as RNAi based natural product”, against several phytopathogens belonging to different families of viruses and fungi.
Regarding ePGBPs as microbial inoculants, the objective of this study was to extend our understanding of five endophytic bacterial strains; Pantoea agglomerans (255-7), Pseudomonas syringae (260-02), Lysinibacillus fusiformis (S4C11), Paraburkholderia fungorum (R8), Paenibacillus pasadenensis (R16); that have shown a promising result in previous studies. In the present doctoral study, these strains were tested in planta to evaluate their role in providing plant growth promotion and broad-spectrum protection against two target pathosystems (viruses and fungi) that might have direct, indirect or simultaneous effects,
proceeded with two following aims: (Aim 1) action against viruses: Cymbidium ringspot virus (CymRSV), Cucumber mosaic virus (CMV), Potato virus X (PVX), and Potato virus Y (PVY) on Nicotiana benthamiana plants, comparing their effects with those of three chitosan-based products, which are known to induce resistance in plants; and (Aim 2) action against fungal pathogens: Rhizoctonia solani, Pythium ultimum and Botrytis cinerea on Lactuca sativa plants, comparing their effects with Bacillus amyloliquefaciens strain (CC2) and Trichoderma spp. based product, under controlled conditions.
To test the priming efficacy of ePGPBs against target viruses, several phenotypic parameters were observed along with the evaluation of three plant defense related genes (EDS1, PR2B and NPR1) on Nicotiana benthamiana plants. Interestingly, the symptoms reduction was successfully registered against CymRSV and CMV with increased heights of the plants. Some of the treatments were shown correlation between severity of sympto
Tipologia IRIS:
Tesi di dottorato
Keywords:
endophytes plant growth-promoting bacteria (ePGPB); plant growth promotion; biocontrol; Induced systemic resistance (ISR); microbiota; nutrition-sensitive agriculture (NSA); dsRNA; RNA interference (RNAi)
Elenco autori:
G.I.R. Shahzad
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