Over the last decades, several biotic and abiotic factors have contributed to the progressive decline of oak formations in Italy. The often-synergistic action of these adverse factors has led to a progressive alteration of the physiological state of plants with a slowdown in development, loss of vitality and ultimately death. Among the biotic agents, a key role is played by some ascomycete fungi, agents of a disease which mainly affects the leaves known as "Mal Bianco". This disease is caused by three obligate pathogens belonging to the genus Erysiphe. These are three species Erysiphe alphitoides, E. hypophylla and E. quercicola, very similar to each other, introduced independently from Asia. The distribution range of the three species in Europe, although overlapping in different countries, presents differences linked to the optimal growth temperature of the three species. Although oak powdery mildew is a disease known for some time in Italy, information on the identity of the species involved and their geographical distribution is still limited. Therefore, a study was conduct to clarify the aetiology of the disease and establish the presence and spread of the three species in Italian oak forests. To this end, in autumn 2023, phytosanitary monitoring was carried out in 13 oak formations distributed in 6 Italian regions and 67 samples of infected leaves were collected from 33 oaks belonging to 3 deciduous species (Cerro, English oak and Roverella). The subsequent diagnostic analyses (morphological and molecular) conducted in the laboratory allowed us to ascertain the identity of the species and to establish for the first time the presence of the 3 species also in Italy: Erysiphe alphitoides (59 samples), Erysiphe hypophylla (8) and Erysiphe quercicola (2). The data obtained in this study confirm that E. alphitoides is the dominant species in Italy too; this pathogen was identified on samples of all oak species and in 6 Italian regions. This is the first study that confirms through molecular investigations the presence, diffusion and geographical distribution of powdery mildew agents on oaks in Italy.
Nel corso degli ultimi decenni numerose avversità biotiche ed abiotiche hanno contribuito al progressivo declino delle formazioni quercine in Italia. L’azione spesso sinergica di vari fattori avversi, ha determinato una progressiva alterazione dello stato fisiologico delle piante con un rallentamento dello sviluppo, perdita di vitalità ed in fine la morte. Fra gli agenti biotici, un ruolo chiave è svolto da alcuni funghi ascomiceti agenti di una malattia che interessa principalmente le foglie nota con il nome di “Mal Bianco”. Questa malattia è causata da tre patogeni obbligati appartenenti al genere Erysiphe. Si tratta di tre specie Erysiphe alphitoides, E. hypophylla e E. quercicola, molto simili tra loro, introdotte dall’Asia in modo indipendente. L’areale di distribuzione delle tre specie in Europa, pur sovrapponendosi in diverse nazioni, presenta delle differenze legate alle esigenze termiche delle tre specie. Nonostante il mal bianco delle querce sia una malattia nota da tempo in Italia sono ancora limitate le informazioni sull’identità delle specie coinvolte e la loro distribuzione geografica. Pertanto, nell’ambito di questa tesi di laurea si è ritenuto opportuno condurre una ricerca sul tema, al fine di chiarire l’eziologia della malattia e stabilire la presenza e diffusione delle tre specie nei querceti italiani. A tal fine nell’autunno 2023 è stato effettuato in 13 formazioni quercine distribuite in 6 regioni italiane un monitoraggio fitosanitario e raccolti 67 campioni di foglie infette da 33 querce appartenenti a 3 specie caducifoglie (Cerro, Farnia e Roverella). Le successive analisi diagnostiche (morfologiche e molecolari) condotte in laboratorio hanno consentito di accertare l’identità delle specie e di stabilire per la prima volta la presenza anche in Italia delle 3 specie: Erysiphe alphitoides (59 campioni), Erysiphe hypophylla (8 campioni) e Erysiphe quercicola (2 campioni). I dati ottenuti in questo studio confermano che anche in Italia E. alphitoides è la specie dominante; questo patogeno è stato identificato sui campioni di tutte le specie quercine e in 6 regioni italiane. Questo è il primo studio che conferma attraverso indagini molecolari la presenza, diffusione e distribuzione geografica degli agenti di Mal Bianco delle querce in Italia.
Diversità e distribuzione geografica di Erysiphe spp. su querce in Italia
CALORE, DAVIDE
2023/2024
Abstract
Over the last decades, several biotic and abiotic factors have contributed to the progressive decline of oak formations in Italy. The often-synergistic action of these adverse factors has led to a progressive alteration of the physiological state of plants with a slowdown in development, loss of vitality and ultimately death. Among the biotic agents, a key role is played by some ascomycete fungi, agents of a disease which mainly affects the leaves known as "Mal Bianco". This disease is caused by three obligate pathogens belonging to the genus Erysiphe. These are three species Erysiphe alphitoides, E. hypophylla and E. quercicola, very similar to each other, introduced independently from Asia. The distribution range of the three species in Europe, although overlapping in different countries, presents differences linked to the optimal growth temperature of the three species. Although oak powdery mildew is a disease known for some time in Italy, information on the identity of the species involved and their geographical distribution is still limited. Therefore, a study was conduct to clarify the aetiology of the disease and establish the presence and spread of the three species in Italian oak forests. To this end, in autumn 2023, phytosanitary monitoring was carried out in 13 oak formations distributed in 6 Italian regions and 67 samples of infected leaves were collected from 33 oaks belonging to 3 deciduous species (Cerro, English oak and Roverella). The subsequent diagnostic analyses (morphological and molecular) conducted in the laboratory allowed us to ascertain the identity of the species and to establish for the first time the presence of the 3 species also in Italy: Erysiphe alphitoides (59 samples), Erysiphe hypophylla (8) and Erysiphe quercicola (2). The data obtained in this study confirm that E. alphitoides is the dominant species in Italy too; this pathogen was identified on samples of all oak species and in 6 Italian regions. This is the first study that confirms through molecular investigations the presence, diffusion and geographical distribution of powdery mildew agents on oaks in Italy.| File | Dimensione | Formato | |
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https://hdl.handle.net/20.500.12608/61770