Rapid diagnostics for Gnomoniopsis smithogilvyi (syn. Gnomoniopsis castaneae) in chestnut nuts: new challenges by using LAMP and real-time PCR methods

Nuts of the sweet chestnut (Castanea sativa) are a widely appreciated traditional food in Europe. In recent years producers and consumers reported a drop of nut quality due to the presence of rot diseases caused by Gnomoniopsis smithogilvyi. Early detection of this pathogen is fundamental to the economic viability of the chestnut industry. In the present study, we developed three molecular methods based on real-time portable LAMP, visual LAMP and qPCR assays for G. smithogilvyi. The molecular assays were specific for G. smithogilvyi and did not amplify the other 11 Gnomoniopsis species and 11 other fungal species commonly associated with chestnuts. The detection limit of both the qPCR and real-time portable LAMP (P-LAMP) assays was 0.128 pg/µL, while the visual LAMP (V-LAMP) assay enabled the detection up to 0.64 pg/µL. By using these newly developed molecular tools, the pathogen was detected in symptomatic and asymptomatic nuts, but not in leaves. The reliability of these molecular methods, including the P-LAMP assay, was particularly useful in detecting G. smithogilvyi of harvested nuts in field, even in the absence of rot symptoms.

Gnomoniopsis smithogilvyi. [Distribution map].

A new distribution map is provided for Gnomoniopsis smithogilvyi Shuttleworth, Liew and Guest. Sordariomycetes: Diaporthales: Gnomoniaceae. Hosts: sweet chestnut (Castanea sativa) and other chestnut species. Information is given on the geographical distribution in Asia (India, Jammu and Kashmir, Turkey), Europe (Belgium, Croatia, Czechia, France, Greece, Italy, Sardinia, Netherlands, Slovenia, Spain, Switzerland, United Kingdom, England), North America (USA, Michigan), Oceania (Australia, New South Wales, Victoria, New Zealand).

The Sprout Regulating Compound 1,4-Dimethylnaphthalene Exhibits Fungistatic Activity

The compound 1,4-dimethylnaphthalene, originally isolated from dormant potatoes, is currently in use as a commercial sprout inhibitor. Growers and processors report a reduction in fungal infections in potatoes treated with DMN resulting in increased yields. To assess the effects of DMN on fungal growth a culture of Fusarium oxysporum was isolated from potato tubers and identified via DNA fingerprinting using the 18ITS ribosomal region. Growth of F. oxysporum was inhibited by 31% after four days of exposure to DMN but overall rate of spore germination was not affected by DMN treatment. The growth of additional fungi, including Alternaria alternata, Aspergillus niger, Epicoccum nigrum, Gnomoniopsis smithogilvyi, Phoma medicaginis, and Pythium ultimum was inhibited by DMN as was suppression of sporulation in A. niger. These results suggest that DMN is fungistatic at the application levels examined.

Gljive povezane s truleži plodova pitomog kestena, s prvim nalazom Gnomoniopsis smithogilvyi u Hrvatskoj

Trulež plodova pitomog kestena uzrokovana parazitskim gljivama može predstavljati značajan problem u plantažnoj proizvodnji te kulture. Tijekom 2018. godine, jaka pojava truleži plodova kestena zabilježena je u mješovitoj plantaži pitomog kestena i oraha u okolici Našica. U nasadu je sakupljeno 78 plodova (sorte Bouche de Betizac, Marsol i Maraval), među kojima su laboratorijskim pregledom u njih 63 utvrđeni simptomi truleži jezgre. Iz svih simptomatičnih plodova izolirane su gljive. Kombiniranom identifikacijom na temelju morfologije i analize sekvenci ITS1-5.8S-ITS2 ribosomske DNA, gljive iz simptomatičnih plodova determinirane su kao Gnomoniopsis smithogilvyi, Neofusicoccum parvum, Botryosphaeria dothidea, Diaporthe eres i Fusarium proliferatum. Vrsta G. smithogilvyi utvrđena je u 47 od 63 ploda (75 %), nakon koje su po zastupljenosti slijedile B. dothidea (11/63 ploda, 17 %), N. parvum (10/63 ploda, 16 %), D. eres (3/63 ploda, 5 %) i Fusarium sp. (1/63 ploda, 1,6 %). U 45 plodova utvrđena je samo jedna vrsta gljive, po dvije vrste nađene su u 11 plodova, a po tri vrste gljive u sedam plodova. Sve gljive utvrđene su na plodovima pitomog kestena u Hrvatskoj po prvi puta. Među njima ističe se prvi nalaz G. smithogilvyi, patogena koji u proteklih nekoliko godina uzrokuje velike štete na plodovima kestena u Europi.

Gnomoniopsis smithogilvyi. [Distribution map].

A new distribution map is provided for Gnomoniopsis smithogilvyi Shuttleworth, Liew and Guest. Sordariomycetes: Diaporthales. Hosts: sweet chestnut (Castanea sativa) and other chestnut species. Information is given on the geographical distribution in Europe (France, Greece, Italy, mainland Italy, Sardinia, Slovenia, Spain Switzerland, UK, England and Wales), Asia (India, Jammu and Kashmir), Oceania (Australia, New South Wales, Victoria, New Zealand).