Research Team in Plant Pathology

Active since the establishment of the  University of Udine, the Research Team in Plant Pathology at the  Department of Agricultural, Food, Environmental and Animal Sciences (DI4A) has wide research interests and expertise, ranging from basic science to field trials, with a passion-driven preference for phytoplasma diseases.

All aspects of the phytoplasmas and the diseases they cause, from epidemiology to genome analysis, diagnosis, physiopathology, control, recovery, taxonomy, and more, are being investigated.

Team scientists and research assistants

Giuseppe Firrao
Nazia Loi
Rita Musetti
Paolo Ermacora
Marta Martini
Emanuela Torelli
Alberto Loschi
Stefano Borselli

Research themes pursued by the team

Plant/Pathogen Interactions

The interaction between pathogens and host tissues is a key aspect of pathogen virulence and host resistance. During the last years we focused our studies on phytoplasmas and their hosts, most of these are important crops for Italian agriculture. Currently we are setting up integrated approaches based on advanced microscopy and molecular techniques to give new insight on the interactions between phytoplasmas and phloem sieve elements and on the phytoplasma manipulation of host gene expression during flowering (Musetti, Firrao) -- PAPERS

Endophytes as strategy for disease control

Plants frequently host endophytic fungi and/or bacteria which, for all or part of their lifecycle, colonize the tissues of living plants without causing disease. Endophytes establish mutualistic relationships with plants also inducing physiological modifications in their hosts, making them more resistant against biotic or environmental stresses.
In a recent work we combined culture-dependent and culture-independent methods to estimate the diversity of grapevine fungal endophytic community, and we also developed a fingerprinting tool based on DGGE (Denaturing Gradient Gel Electrophoresis) useful to describe and compare the fungal diversity in grapevine plants. Recent research activities focus on the use endophytic microorganisms as an alternative strategy against plant pathogens affecting economically important crops. An example is given by P.s.actinidiae (see below) and kiwi plants: starting from asymptomatic individuals selected in highly epidemic areas, endophytic organisms were isolated and tested for their antimicrobial activity. Some promising results obtained in vitro will be tested in artificial infection under controlled and field conditions. (Martini, Musetti) -- PAPERS

Bacterial canker of kiwifruit

Pseudomonas syringae pv. actinidiae is an emerging plant pathogenic bacterium that caused severe production losses in Italy. It has recently also been found in Friuli Venezia Giulia. We are conducting field studies in order to develop specific suitable measures for the containement of the disease in our area. We also pjoneeried the genomic studies on this bacterium with the aim of detecting the features that made this bacterium so aggressive. It was found that the Pseudomonas syringae subsp. actinidiae that cause the present outbreak in Italy and in other parts of the world has incorporated a large fraction of exogeneous DNA that expanded its pathogenetic capabilities. (Ermacora - Firrao -  Martini) -- PAPERS

DNA origami

Nanobiotechnology is a new approach to the challenge of an efficient and environmentally friendly production. In agricolture, we believe that nanotechnology will play a significant role in the development of innovative methods for pathogen control in the near future. Our current aim is the development of nanorobots capable of responding to molecular signals. For the construction of such a nanorobot, we used a technique named DNA-origami where, as in the Japanese art of paper folding, a single stranded DNA molecule is folded into a desired shape by hybridization to synthetic oligonucleotides. (Torelli - Firrao) -- Papers

Assesment of mycotoxin contamination risk

Food contamination with fungal secondary metabolites has been a major limit for population wellness and development in the past. Although today social protection against this plague has been established in most countries, there are still many areas in the world where mycotoxin contamination causes illness, due to the lack of healthy conditions for the storage of commodities.
Information and knowledge are the main weapons available to contrast the danger of food contamination by mycotoxins. Prevention is the winning strategy not only for the consumer, but also as far as the production is concerned. Rapid methods for the early detection of contaminants and quality assessment are being introduced in the routine field operation, leading to substantial improvements of product quality.
We focused our research on the development and evaluation of innovative methods for the early assessment of contamination risk: i) aerobiological sampling of fungal spores; ii) comparative image analysis with near infrared illumination; iii) Fourier transform near infrared spectroscopy (FT-NIR) implemented with integrating sphere; iv) prediction model based on agronomic data with neural network approach. (Torelli - Firrao) -- PAPERS

Environmental-friendly methods to control diseases

The unavailability of direct methods to control phytoplasmas emphasizes the role of prevention of the disease spread, particularly through the control of natural vectors. Concerning European Stone Fruit Yellows (ESFY), the main stone fruit disease in North East Italy, a control approach based on repellent effect against the vector Cacopsylla pruni was set up. In semi-controlled conditions, the spreading of ESFY in conifer extract-treated plots was reduced similarly to the plots treated with systemic insecticides.
Another innovative approach in phytoplasma disease control was based on increasing  resilience of the cultivated system. In particular, the model apricot-ESFY was investigated. A clear effect in increased tolerance to ESFY was reported in apricot plants cloned from individuals recovered from the disease, when compared to plants of the same genotype, obtained from never-infected plants.  (Ermacora, Loi) -- PAPERS

In the case of other important diseases, e.g. Rhizoctonia solani root rot on lamb’s lettuce and sooty blotch disease of apple caused by Alternaria spp., potential biocontrol agents have been selected and tested in vitro and in controlled conditions. (Ermacora - Martini) -- PAPERS

Molecular detection, identification, and differentiation of phytoplasmas

Accurate identification and early detection of pathogens is a crucial step in plant disease management. To date an increasing number of nucleic acid based molecular methods have been adopted for routine detection of pathogens in diagnostic laboratories. Recently, diagnostic PCR has been greatly improved by the introduction of the real-time PCR, which permits to detect and also to quantify the target pathogen in the sample. In our laboratory molecular detection protocols based on real-time PCR have been developed for specific detection and quantification of ‘Candidatus Phytoplasma prunorum’ and ‘Ca. P. mali’ in their natural host.
The differentiation and identification of closely related, distinct phytoplasma strains may be extremely useful for disease epidemiological studies or for quarantine regulations. Our work contributed to the demonstration that the differentiation of distinct phytoplasma strains can be enhanced by analyzing genetic markers less conserved than 16S rDNA, such as ribosomal protein (rp) and secY genes.(Martini, Ermacora) -- PAPERS

Genomics of plant pathogens

A look in the genome features of the pathogens may provide valuable hints to understand why and how they cause diseases. Recently, we used the so called Second Generation Sequencing to investigate the genomes of bacterial strainsbelonging to Pseudomonas syringe pv. syringae, P.s. pv. actinidiae, P.s. pv. theae, P. avellanae, P. savastanoi, "Candidatus Phytoplasma asteris", Ca. P. pruni", Xanthomonas perforans, and more. The genome studies provided information that is being exploited for the characterization of pathogenicity factors and for the refinement of the taxonomy of the groups involved. (Torelli - Firrao) -- PAPERS

Etiology and epidemiology of phytoplasma diseases

A important area of interest is related to phytoplasma diseases epidemiology, mainly concerning the phytoplasmas that affect fruit-trees and grapevine. Such as Grapevine yellows, as European Stone fruit Yellows, Apple proliferation, Pear decline epidemics are recurrent in North-East Italy, and studies are carried out on vectors presence, spreading and infectivity. A close cooperation was established with the local phytosanitary service in order to apply the best management techniques to counteract disease spreading. (Ermacora, Loi) -- PAPERS