Amatulli, Maria Teresa

Bertetti, Domenico

Cardinale, J.

Garibaldi, Angelo

Gullino, Maria Lodovica

English

Amatulli, MARIA TERESA

Institutional Research Information System University of Turin

This full text was downloaded from iris - AperTO: https://iris.unito.it/iris - AperTOUniversity of Turin’s Institutional Research Information System and Open Access Institutional RepositoryThis is the author's final version of the contribution published as:Garibaldi A.; Bertetti D.; Amatulli M. T.; Cardinale J.; Gullino M.L.. Firstreport of postharvest Fruit Rot in avocado (Persea americana) caused byLasiodiplodia theobromae in Italy.. PLANT DISEASE. 96 pp: 460-460.When citing, please refer to the published version.Link to this full text:http://hdl.handle.net/2318/130604First Report of Postharvest Fruit Rot in Avocado (Persea americana Mill.) Caused by 1 Lasiodiplodia theobromae (Pat.) Griffon & Maubl. in Italy. A. Garibaldi, D. Bertetti, M.T. 2 Amatulli, J. Cardinale and M. L. Gullino, Centre of Competence for the Innovation in the Agro-3 Environmental Sector (AGROINNOVA) Via Leonardo da Vinci 44, 10095 Grugliasco, Italy. 4  5 Avocado (Persea americana Mill.) is grown in some areas of southern Italy. In spring 2011,  a 6 previously unknown rot was observed on  fruit marketed in Torino (northern Italy). The decayed 7 area started from the stalk and appeared irregular, soft, and was surrounded by a dark brown 8 margin. The internal decayed area appeared rotten, brown, and surrounded by bleached tissue. 9 Fragments (approximately 3 mm) were taken from the margin of the internal diseased tissues, 10 cultured on potato dextrose agar (PDA) and incubated at temperatures between 21-25°C, under 11 alternating light and darkness. Colonies of the fungus initially appeared whitish, later turning 12 mouse grey to black. Mature mycelium was septate and produced a dark pigment. The fungus, 13 grown on oat-agar (2) and incubated at temperatures between 21-25°C, under alternating light 14 and darkness produced grayish colonies, with a fluffy aerial mycelium which became dark with 15 age and produced black pigments. After 18 day, such colonies produced pycnidia aggregated into 16 stromatic masses, emerging from decayed tisues, up to 3-4  mm in diameter. Conidia produced in 17 the pycnidia were initially unicellular, hyaline, granulose, ovoid to ellipsoidal,  measuring 20.8 – 18 26.9 x 12.5 -16.1  (average 24.4 x 13.5) µm. After 7 days, mature conidia became darker and 19 uniseptate. The morphological characteristics of mycelia, pycnidia and conidia observed with a 20 light microscope permitted to identify the fungus as Lasiodiplodia theobromae  (3). The Internal 21 Transcribed Spacer (ITS) region of rDNA was amplified using the primers ITS1/ITS4, and 22 sequenced. BLAST analysis (1) of the 488 bp segment showed a 100% similarity with the 23 sequence of Lasiodiplodia theobromae Pat. Griffon & Maubl (GeneBank accession GQ502453). 1 The nucleotide sequence has been assigned the GenBank Accession JN849098. Pathogenicity 2 tests were performed by inoculating three avocado fruits after surface-disinfesting in 1% sodium 3 hypochlorite and wounding. Mycelial disks (8 mm diameter), obtained from PDA cultures of one 4 strain, were placed on wounds. Three control fruits were inoculated with plain PDA. Fruits were 5 incubated at 14-20 °C. The first symptoms developed 5 days after the artificial inoculation. After 6 7 days, the rot was very evident and L. theobromae was consistently reisolated. Non-inoculated 7 fruit remained healthy. The pathogenicity test was performed twice. To our knowledge, this is 8 the first report of the presence of L. theobromae on avocado in Italy, as well as in Europe.  The 9 occurrence of postharvest fruit rot on avocado caused by L. theobromae was described in many 10 producing areas such as the US (4), South Africa and Israel. In Italy, the economic importance of 11 avocado cultivation is at present limited.  12  13 References: (1) S.F. Altschul et al. Nucleic Acids Res., 25:3389, 1997. (2). Narayanasamy. 14 Microbial Plant Pathogens. Detection and Disease Diagnosis: Fungal Pathogens. Springer, 15 Dordrecht, 201 pages, 2011. (3) E. Punithalingam. CMI Description of Fungi and bacteria. Sheet 16 519, 1976. (4) H.E. Stevens, R.B. Piper. Circular USDA n. 582, 46 pages, 1941.  17  18 

First report of postharvest Fruit Rot in avocado (Persea americana) caused by Lasiodiplodia theobromae in Italy.

https://iris.unito.it/retrieve/handle/2318/130604/261111/COPERTINA%20First%20Report%20of%20Postharvest%20Fruit%20Rot%20in%20Avocado.pdf

First report of postharvest Fruit Rot in avocado (Persea americana) caused by Lasiodiplodia theobromae in Italy.

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