Tesi etd-11252024-093630
Link copiato negli appunti
Tipo di tesi
Dottorato
Autore
DI PACO, LORENZO
Indirizzo email
lorenzodipaco93@gmail.com
URN
etd-11252024-093630
Titolo
The protective role of iodine against fungal pathogens in Arabidopsis thaliana
Settore scientifico disciplinare
BIO/04
Corso di studi
Istituto di Scienze della Vita - PhD in Agrobioscienze - PON
Commissione
relatore Prof. PERATA, PIERDOMENICO
Parole chiave
- Arabidopsis thaliana
- Botrytis cinerea
- ethylene
- glucosinolates
- Golovinomyces cichoracearum
- hydrogen peroxide
- iodine
- jasmonic acid
- salicylic acid
- transcriptomics
Data inizio appello
10/02/2025;
Disponibilità
parziale
Riassunto analitico
The physiological role of iodine in plants has been debated for many years. Several papers, conducted working with phylogenetically distant species, report the beneficial effect of micromolar amounts of iodine on plant growth and yield, not demonstrating its functional action. Nevertheless, based on new evidence mainly achieved working with the model plant Arabidopsis thaliana, which include the demonstration of the presence of iodinated proteins in plants, iodine has been recently identified as a plant nutrient. As a consequence, iodine has been recently included in the list of nutrients by the International Fertilizer Association (IFA).
Among the beneficial effects which are ascribed to the iodine-based fertilization, the protective role of iodine against abiotic stress, such as salt stress or heavy metals tolerance, has been demonstrated. Nevertheless, the role of iodine in plant protection has never been investigated so far, even if several evidence suggest its potential involvement in the plant-pathogenic responses. For instance, at transcriptional level, micromolar amounts of iodine specifically regulate the expression of several genes largely involved to plant response to biotic stresses. In particular, a clear correlation between several iodine-responsive genes and those typically modulated in the presence of fungal infection, salicylic acid (SA) or synthetic analogues of SA has been demonstrated. In addition, the iodinated proteins which have been identified in Arabidopsis root tissues are mainly related to the action of various peroxidases, which can be involved in the response to various biotic stress.
The aim of the present study is to investigate in a systematic way the possible effects of micromolar amounts of iodine in the plant response against pathogen attacks. The research was conducted working with Arabidopsis thaliana. The protective effect of diverse iodine forms (iodide and iodate, supplied as KI or KIO3) and application methods (short or chronic treatment) was evaluated on a collection of fungal pathogens (Botrytis cinerea, Fusarium oxysporum, Phytophthora capsici, Golovinomyces cichoracearum), which are characterized by different lifestyles (biotrophic, necrotrophic or hemibiotrophic).
The phenotypic characterization of the plant tolerance towards the different pathogens clearly demonstrated the protecting effect of iodine in alleviating the biotic stress. Both the iodine forms and administration methods (short and chronic application) provided positive outcomes in terms of plant protection, even if with different extents.
We further characterized the iodine-mediated tolerance, by selecting B. cinerea as a model for necrotrophic pathogens and G. cichoracearum (the causative agent of powdery mildew) as a model of biotrophic pathogens. The iodine-driven plant tolerance was analysed at the hormonal level, by quantifying the main hormones which are involved in plant defense, which are salicylic acid (SA), jasmonic acid (JA), ethylene (ET) and abscisic acid (ABA). Moreover, the transcriptional response of target genes involved in defense response was characterized. To gain a broader understanding of the transcriptional impact of KI and KIO3 on A. thaliana resistance mechanisms, the whole-transcriptome sequencing was also performed by RNA-Seq. The protective effect of iodine was also characterized in light of hydrogen peroxide (H2O2) accumulation and the free amino acids composition. These determinations were selected as H2O2 is a signalling molecule regulating a multitude of physiological processes, including the host-pathogen recognition/resistance mechanisms, whereas free amino acids are essential precursors for many secondary metabolites produced by the plant in response to pathogenic attacks.
Overall, our results suggest that iodine is able to activate a broad spectrum of immune-like responses, which are at the base of the enhanced plant tolerance. Fertigation with KI or KIO3 at very low concentrations could represent an innovative strategy to control fungal diseases and potentially a broad range of plant pathogens. This possibility can be alternative/additional to the use of traditional pesticides, thus reducing the environmental impact of such an agronomic practice. Moreover, from a broader perspective, the present study adds a further piece to the puzzle on the functional role of iodine for plants.
Among the beneficial effects which are ascribed to the iodine-based fertilization, the protective role of iodine against abiotic stress, such as salt stress or heavy metals tolerance, has been demonstrated. Nevertheless, the role of iodine in plant protection has never been investigated so far, even if several evidence suggest its potential involvement in the plant-pathogenic responses. For instance, at transcriptional level, micromolar amounts of iodine specifically regulate the expression of several genes largely involved to plant response to biotic stresses. In particular, a clear correlation between several iodine-responsive genes and those typically modulated in the presence of fungal infection, salicylic acid (SA) or synthetic analogues of SA has been demonstrated. In addition, the iodinated proteins which have been identified in Arabidopsis root tissues are mainly related to the action of various peroxidases, which can be involved in the response to various biotic stress.
The aim of the present study is to investigate in a systematic way the possible effects of micromolar amounts of iodine in the plant response against pathogen attacks. The research was conducted working with Arabidopsis thaliana. The protective effect of diverse iodine forms (iodide and iodate, supplied as KI or KIO3) and application methods (short or chronic treatment) was evaluated on a collection of fungal pathogens (Botrytis cinerea, Fusarium oxysporum, Phytophthora capsici, Golovinomyces cichoracearum), which are characterized by different lifestyles (biotrophic, necrotrophic or hemibiotrophic).
The phenotypic characterization of the plant tolerance towards the different pathogens clearly demonstrated the protecting effect of iodine in alleviating the biotic stress. Both the iodine forms and administration methods (short and chronic application) provided positive outcomes in terms of plant protection, even if with different extents.
We further characterized the iodine-mediated tolerance, by selecting B. cinerea as a model for necrotrophic pathogens and G. cichoracearum (the causative agent of powdery mildew) as a model of biotrophic pathogens. The iodine-driven plant tolerance was analysed at the hormonal level, by quantifying the main hormones which are involved in plant defense, which are salicylic acid (SA), jasmonic acid (JA), ethylene (ET) and abscisic acid (ABA). Moreover, the transcriptional response of target genes involved in defense response was characterized. To gain a broader understanding of the transcriptional impact of KI and KIO3 on A. thaliana resistance mechanisms, the whole-transcriptome sequencing was also performed by RNA-Seq. The protective effect of iodine was also characterized in light of hydrogen peroxide (H2O2) accumulation and the free amino acids composition. These determinations were selected as H2O2 is a signalling molecule regulating a multitude of physiological processes, including the host-pathogen recognition/resistance mechanisms, whereas free amino acids are essential precursors for many secondary metabolites produced by the plant in response to pathogenic attacks.
Overall, our results suggest that iodine is able to activate a broad spectrum of immune-like responses, which are at the base of the enhanced plant tolerance. Fertigation with KI or KIO3 at very low concentrations could represent an innovative strategy to control fungal diseases and potentially a broad range of plant pathogens. This possibility can be alternative/additional to the use of traditional pesticides, thus reducing the environmental impact of such an agronomic practice. Moreover, from a broader perspective, the present study adds a further piece to the puzzle on the functional role of iodine for plants.
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