Analysis of virulence and genetic variability of Alternaria alternata associated with leaf spot disease in potato plants in Iran

Abstract

Leaf spot disease in potato is caused by Alternaria alternata (Fr.) Keissler, an opportunistic pathogen that infests many agricultural crops worldwide in the field and during postharvest storage of vegetables and fruits. Alternaria alternata is associated with leaf spot disease in potato in Iran. Thus, there is a need to investigate the virulence and genetic variability of Iranian A. alternata isolates to facilitate the development of appropriate management strategies. In the present study, we analyzed a total of 28 isolates obtained from the main potato-growing regions of Iran, including the Ardebil, Hamedan, Isfahan, and Fars provinces. The pathogens were characterized based on sequence analysis of the genes encoding glyceraldehyde-3-phosphate dehydrogenase (gpd), plasma membrane ATPase, Alternaria allergen a 1 (Alt a1), calmodulin, and actin. In addition, random amplified polymorphic DNA (RAPD), intersimple sequence repeat (ISSR), and virulence studies were performed. Phylogenetic analysis of the combined dataset indicated that the five representative isolates were grouped with the subcluster comprising A. alternata. RAPD and ISSR analyses clustered the 28 A. alternata isolates into different groups with no correlation with their corresponding geographical origins. Results of the pathogenicity assay indicated that all A. alternata isolates were pathogenic against potato. However, the A. alternata isolates showed high variability in terms of virulence.

Fungal Allergen and Mold Allergy Diagnosis: Role and Relevance of Alternaria alternata Alt a 1 Protein Family

“…In recent years, multigene phylogeny has been widely employed for the identification and characterization of Alternaria species. Molecular approaches based on barcoding the gene region or gene fragments, such as the internal transcribed spacer (ITS) [ 85 , 86 , 87 , 88 ], mitochondrial small subunit (mtSSU), large subunit ribosomal DNA (LSU) [ 87 ], A. alternata major allergen (Alt a 1) [ 87 , 89 , 90 ], glyceraldehyde-3-phosphate dehydrogenase (GAPDH) [ 86 , 87 , 88 , 89 ], anonymous genomics regions (OPA 1–3 and OPA 2–1) [ 85 , 88 , 89 ], translation elongation factor 1 (TEF1) [ 87 , 88 , 89 ], RNA polymerase, the second largest subunit (RPB2) [ 87 , 88 ], plasma membrane, ATPase, calmodulin [ 87 , 89 ] and actin [ 89 ], have been used to define the monophyly of Alternaria-Nimbya-Embellisia-Ulocladium in the Ascomycete family Pleosporaceae relationships [ 74 ]. Current advances, especially in multi-gene phylogeny and comparative genomics, have made it possible to redefine and delineate the different Alternaria sections, with accurate molecular differentiation and identification of isolates showing that the Alternaria section consists of 11 phylogenetic species and 1 species complex [ 71 , 72 , 73 ].…”

Morphological and molecular identification study of rose and lantana fungal leaf spot pathogens

“…It is worth noting that the disease symptoms began to appear ten days after the inoculation on both plants under study, beginning with the fungus A. alternata followed by B. cinerea, while symptoms began to appear with a long time with F. chlamydosporum. The superiority of the pathogenic fungus A. alternata in causing disease and the emergence of disease symptoms on each of the plants under study (rose and lantana) is due to the action of enzymes degrading cellulose, pectin, fats lipids and others, as well as the important role of mycotoxin in the occurrence of symptoms on plants [27,30]. ).…”

Novel Cucumis enzymes associated with host-specific disease resistance to Phytophthora melonis Katsura

“…Inoculum was obtained by growing the P. melonis isolate in 500-mL flasks containing Water-soaked wheat seeds, which had been autoclaved at 120 C for 30 min on 2 consecutive days. The flasks were inoculated with 5 cm disks cut from a 10-day-old culture of the P. melonis isolate, and placed in the dark for 2 weeks at 25 ± 2 C. then, 45-day-old seedlings were inoculated by 10 g of wheat seed (106 sporangia mL À1 ) and incubated for two days under saturated moist conditions in the greenhouse [6,[29][30][31]. In the seedling stage, inoculated and control root samples were harvested in three biological replicates over the time courses of 7, 14 and 21 days after inoculation (DAI) and then immediately transferred to liquid nitrogen and kept at À80 C. All experiments were repeated three times.…”