鏈格菌

Alternaria Nees, Syst. Pilze, Suppl. (Würzburg): 72 (1816).

Alternaria è un genere di funghi che comprende specie che causano un tipo di muffa, particolarmente diffusa in Italia, che cresce su frutta e verdura in decomposizione e in ambienti particolarmente umidi (caratterizzati da una temperatura che varia tra i 18° e i 32° ed un tasso di umidità superiore al 65%) rilasciando le sue spore soprattutto su carta da parati, tappeti e terriccio. È una delle principali cause di reazioni allergiche quali asma, congiuntivite, rinite e dermatiti. L'insorgenza degli attacchi avviene principalmente tra metà luglio e settembre, periodo nel quale si ha la massima concentrazione di spore nell'aria, ma in generale il rischio sussiste a temperature superiori ai 18 °C.

Specie

Il genere Alternaria comprende specie saprofite e specie parassite; queste ultime causano svariate patologie soprattutto su piante erbacee. Dal punto di vista fitopatologico le specie più importanti di questo fungo sono:

• Alternaria alternata
• Alternaria brassicae
• Alternaria circinans
• Alternaria citri
• Alternaria cucumerina
• Alternaria dianthi
• Alternaria fici
• Alternaria macrospora
• Alternaria porri
• Alternaria solani
• Alternaria tenuis (specie tipo)
• Alternaria tabacina
• Alternaria zinniae

Patologia

Catena di conidi di Alternaria sp.

Le spore di Alternaria sono di ridottissime dimensioni e, similarmente ai pollini, vengono inalate facilmente provocando allergia in soggetti intolleranti.

Sintomatologia

Le affezioni da alternaria provocano:

• Tosse
• Irritazione agli occhi (congiuntivite allergica)
• Disturbi respiratori
• Rinite
• Problemi cutanei

Consigli generali

• Conservare in maniera adeguata gli alimenti in cucina
• Non accatastare legni e materiale in luoghi umidi
• Effettuare frequentemente la manutenzione degli impianti di condizionamento
• Utilizzare, se possibile, un deumidificatore
• Evitare alimenti ricchi di muffe come formaggi stagionati, sottaceti, cibi affumicati e frutta secca

Bibliografia

• (EN) Alternaria, in Index Fungorum, CABI Bioscience.

Pubblicazioni scientifiche sul genere Alternaria

• Anderson, B., Kroger, E. & Roberts, R.G. 2001. Chemical and morphological segregation of Alternaria alternata, A. gaisen and A. longipes. Mycological Research 105:291-299.
• Anderson, B., Kroger, E. & Roberts, R.G. 2002. Chemical and morphological segregation of Alternaria arborescens, A. infectoria and A. tenuissima species-groups. Mycological Research 106:170-182.
• Anderson, B. and Thrane, U. 1996. Differentiation of Alternaria infectoria and Alternaria alternata based on morphology, metabolite profiles, and cultural characteristics. Canada Journal Microbiology 42:685-689.
• Aradhya, M.K., Chan, H.M. & Parfitt, D.E. 2001. Genetic variability in the pistachio late blight fungus, Alternaria alternata. Mycological Research 105:300-306.
• Chou H.H., and Wu W.S. 2002. Phylogenetic analysis of internal transcribed spacer regions of the genus Alternaria, and the significance of filament-beaked conidia. Mycological Research 106:164-169.
• Cooke, D.E.L., Forster, J.W., Jenkins, P.D., Jones, D.G. & Lewis, D.M. 1998. Analysis of intraspecific and interspecific variation in the genus Alternaria by the use of RAPD-PCR. Annals Applied Biology 132:197-209.
• Elliott, John A. 1917. Taxonomic characters of the genera Alternaria and Macrosporium. American Journal of Botany. 4:439-476.
• Groves, J.W. and Skolko, A.J. 1944. Notes on seed borne fungi II Alternaria. Canadian Journal of Research 22:217-234.
• de Hoog, G.S. and Horre, R. 2002. Molecular taxonomy of the Alternaria and Ulocladium species from humans and their identification in the routine laboratory. Mycoses 45:259-276.
• Jasalavich, C.A., Morales, V.M., Pelcher, L.E. & Seguin-Swartz, G. 1995. Comparison of nuclear ribosomal DNA sequences from Alternaria species pathogenic to crucifers. Mycological Research 99:604-614.
• Kusaba, M., and Tsuge, T. 1995. Phylogeny of Alternaria fungi known to produce host-specific toxins on the basis of variation in internal transcribed spacers of ribosomal DNA. Current Genetics 28:491-498
• Kusaba, M., Tsuge, Takashi. 1994. Nuclear ribosomal DNA variation and pathogenic specialization in Alternaria fungi known to produce host-specific toxins. Applied and Environmental Microbiology 60:3055-3062.
• McKay, G.J., Brown, A.E., Bjourson, A.J. & Mercer, P.C. 1999. Molecular characterisation of Alternaria linicola and its detection in linseed. European Journal of Plant Pathology 105:157-166.
• Peever, T.L., Ibanez, A., Akimitsu, K. & Timmer, L.W. 2002. Worldwide phylogeography of the citrus brown spot pathogen, Alternaria alternata. Phytopathology. 92: 794-802.
• Pryor, B. M., and Lichailides, T.J. 2002. Morphological, pathogenic, and molecular characterization of Alternaria isolates associated with Alternaria late blight of pistachio. Phytopathology 92:406-416.
• Pryor, Barry M., and Gilbertson, Robert L. 2002.Relationships and taxonomic status of Alternaria radicina, A. carotiincultae, and A. petroselini based upon morphological, biochemical, and molecular characteristics. Mycologia 94: 49-61.
• Pryor, Barry M., and Gilbertson, Robert L. 2000. Molecular phylogenetic relationships amongst Alternaria species and related fungi based upon analysis of nuclear ITS and mt SSU rDNA sequences. Mycological Research 104:1312-1321.
• Roberts, R.G., Reymond, S.T. & Anderson, B. 2000. RAPD fragment pattern analysis and morphological segregation of small-spored Alternaria species and species group. Mycological Research 104:151-160.
• Sharma T.R. and Tewari, J.P.1998. RAPD analysis of three Alternaria species pathogenic to crucifers. Mycological Research 120:807-814.
• Simmons, Emory G. 1967. Typification of Alternaria, Stemphylium, and Ulocladium. Mycologia 59:67-92.
• Simmons, Emory G. 1981. Alternaria themes and variations. Mycotaxon 13:16-34.
• Simmons, Emory G. 1982. Alternaria themes and variations (7-10). Mycotaxon 14:17-43.
• Simmons, Emory G. 1982. Alternaria themes and variations (11-13). Mycotaxon 14:44-57.
• Simmons, Emory G. 1986. Alternaria themes and variations (14-16). Mycotaxon 25:195-202.
• Simmons, Emory G. 1986. Alternaria themes and variations (17-21). Mycotaxon 25:203-216.
• Simmons, Emory G. 1986. Alternaria themes and variations (22-26). Mycotaxon 25:287-308.
• Simmons, Emory G. 1990. Alternaria themes and variations (27-53). Mycotaxon 37:79-119.
• Simmons, Emory G. 1993. Alternaria themes and variations (54-62). Mycotaxon 46:171-199.
• Simmons, Emory G. 1993. Alternaria themes and variations (63-72). Mycotaxon 48:91-107.
• Simmons, Emory G. 1993. Alternaria themes and variations (73). Mycotaxon 48:109-140.
• Simmons, Emory G. 1994. Alternaria themes and variations (74-105). Mycotaxon 50:219-270.
• Simmons, Emory G. 1994. Alternaria themes and variations (106-111). Mycotaxon 50:409-427.
• Simmons, Emory G. 1995. Alternaria themes and variations (112-144). Mycotaxon 55:55-163.
• Simmons, Emory G. 1996. Alternaria themes and variations (145-149). Mycotaxon 57:391-409.
• Simmons, Emory G. 1996. Alternaria themes and variations (150). Mycotaxon 59:319-335.
• Simmons, Emory G. 1997. Alternaria themes and variations (151-223). Mycotaxon 65:1-91.
• Simmons, Emory G. 1998. Alternaria themes and variations (226-235). Mycotaxon 70:263-323.
• Simmons, Emory G. 1999. Alternaria themes and variations (236-243). Mycotaxon 70:325-369.
• Simmons, Emory G. 2000. Alternaria themes and variations (244-286). Mycotaxon 75:1-115.
• Tsuge, T., Kobayashi, H. & Nishimura, S. 1989. Organization of ribosomal RNA genes in Alternaria alternata Japanese pear pathotype, a host-selective AK-toxin-producing fungus. Current Genetics 16:267-272.
• Weir, T.L., Huff, D.R., Christ, B.J. & Romaine, C.P. 1998. RAPD-PCR analysis of genetic variation among isolates of Alternaria solani and Alternaria alternata from potato and tomato. Mycologia 90:813-821.
• Wiltshire, S.P. 1933. The foundation species of Alternaria and Macrosporium. Transactions British Mycological Society 18:135-160.
• Zhang, Tian-Yu and Zhang, Jing-Ze. 1999. Taxonomic studies of Alternaria from China: New species and new records to China on Cruciferae, Cucurbitaceae, and Euphorbiaceae. Mycotaxon 72:423-432.
• Zhang, T.Y., Zhang, J.Z., Chen, W.Q., Ma, X.L. & Gao, M.X. 1999. Taxonomic studies of Alternaria from China: New taxa on Fagaceae, Magnoliaceae, Meliaceae, and Moraceae. Mycotaxon 72: 433-441.
• Zhang, T.Y. 1999. Taxonomic studies of Alternaria from China: New species and new records on Gramineae, Iridiaceae, and Liliaceae. Mycotaxon 72:443-453.