فصلنامه بیماریهای گیاهی
سال پنجاه و هشتم شماره 2 (زمستان 1401)

Tomato yellow leaf curl virus (TYLCV) is one of the most important tomato infecting viruses worldwide. In this study, symptomatic plant samples of Moldavian dragonhead (Dracocephalum moldavica L.), broad bean, soybean, basil and euphorbia (Euphorbia sp. L.) were collected from Jiroft farms (Kerman province) in 2018-2019 and TYLCV infection as well as association of Tomato leaf curl betasatellite (ToLCB) and/or Gossypium darwinii symptomless alphasatellite (GDarSLA) with some of the samples were identified. Complete nucleotide sequences of the genome of five selected TYLCV isolates obtained from five plant hosts shared identities of 90-99% with each other and 88-97 with the selected GenBank isolates of TYLCV. Furthermore, the genome of ToLCB isolates from Moldavian dragonhead, broad bean, soybean and basil shared identities of 96-99% with each other and 94-95% with the counterpart betasatellite molecules from the GenBank database. Nucleotide sequence of GDarSLA, identified in soybean shared 93-98% identities with two Iranian GenBank isolates of GDarSLA. The above five plants are reported as new natural hosts of TYLCV, ToLCB and/or GDarSLA in Iran and also Moldavian dragonhead as well as broad bean are reported as new natural hosts of the virus in the world. Results of the current study indicate that TYLCV and the associated betasatellite have a wide distribution in Jiroft farms (Kerman province).

The aim of this study is to investigate the interaction effects of two Trichoderma spices (T.koningii and T. virens) mutants and endophyte Piriformospora indica on infected cucumber plants by Fusarium oxysporum f. sp. radicis-cucumerinum (Forc) and evaluating their mutual influence on growth indexes in cucumber plants.The efficient wild-type Trichoderma isolates were selected by dual-culture test (T.koningii NAS-108 with 50% and T.virens NAS-115 with 33% inhibition of pathogenic growth) and their spore suspension with a concentration of 106 (spore/ml) in a dose range of 250 Gy was irradiated with gamma rays. NARS-TKM101 and NARS-TviM112 mutants showed highest antagonistic activity by 20% and 100% increase compared to their wild-type strains and they with their wild-type strains, were used for greenhouse evaluations. The combined treatments of Trichoderama sp. (total wild types and total mutants) with P. indica showed the most positive effects on seedlings growth indices length and dry weight (stem and root). No significant difference was observed between un-irradiated and mutant strains of Trichoderma in reducing disease index, (p<5%), but the combined treatments of two Trichoderma fungi (total mixed Trichoderama wild types and total mutants) with P. indica led to significant reduction of disease index (p<5%) and were more successful than the carbendazim fungicide in the plants infected with Forc.

During the visit of some banana cultivation areas in 2021 and 2022, sampling of leaves and roots with symptoms of leaf spot and wilting was done in Sistan and Baluchistan, and Hormozgan provinces. After being transferred to the laboratory, twenty-eight isolates belonging to the genus Fusarium sensu lato were isolated from the infected samples.. The isolates were identified by carnation leaf agar and SNA under 12 hours of near UV light and 12 hours of darkness. The results of the morphological investigation and phylogenetic analysis based on Elongation factor 1-α (EF 1-α) gene region showed that isolates belonged to Fusarium oxysporum (12 isolates), Fusarium incarnatum (10 isolates), Neocosmospora sp. (7 isolates), and two unknown isolates of Fusarium. The pathogenicity test was conducted to compare the pathogenicity of the species on the Dwarf Cavendish banana variety. Pathogenicity test results showed the isolates could cause leaf spot (Fusarium sp. and Fusarium incarnatum) and wilting (Fusarium oxysporum, Fusarium incarnatum and Neocosmospora sp.) in banana plants under greenhouse conditions. Based on our knowledge, this is the first report of F. incarnatum and Neocosmospora sp. pathogenicity of banana in Iran.

Fusarium wilt is one of the most important diseases of tomato seriously threatening the cultivation and development of this crop worldwide. In this study, the biocontrol potential of four basidiomycota fungal endophytes isolated from wheat and wild oat, namely Rhizoctonia endophytica M32, R. zeae M9, Fomes inzengae M40 and Coprinopsis urticicola M2, was evaluated against fusarium wilt of tomato under laboratory and greenhouse conditions. In lab, identity and race of the pathogen was first determined using phylogenetic inference and specific primers. In addition, antagonistic potential of fungal endophytes in inhibiting the pathogen and possible plant resistance induction was assessed through dual culture, volatile metabolite production, pot cultivation, split-root and root-cutting tests. Molecular evidence determined the identity of the pathogen as Fusarium oxysporum f. sp. lycopersici race 3. Lab tests showed that in duel culture test all four fungal endophytes were able to reduction of colony diameter of pathogen significantly five and seven days after inoculation compared to control. In volatile metabolite test all isolates could reduce mycelial growth of the pathogen significantly compared to control except R. zeae M9 in third and fifth day. Under greenhouse condition, only C. urticicola M2 isolate could significantly reduce the severity of fusarium wilt of tomato and increase plant growth factors compared to the control and other fungal endopytes. Through split-root and root-cutting tests, the possible mechanism of disease severity reduction caused by C. urticicola M2 was identified as stimulation and induction of resistance in tomato plant.

The genus Pseudoaulolaimus Imamura, 1931 along with the genus Aulolaimus are placed in the family Aulolaimidae Jairajpuri & Hooper, 1968, suborder Leptolaimina and order Areolaimida. Pseudoaulolaimus anchilocaudatus Imamura, 1931, is the only species in this genus, which was for the first time described by Imamura (1931) from a rice field in Japan. This species and the genus as well are mainly characterized by an anchor-like (fork-shaped) end of the tail in both males and females, which is a unique feature among all the known free-living members of the phylum Nematoda. The type material of this species was lost during World War II. However, more than 50 years after its first description, Sturhan and Lorenzen (1982) collected and reported P. anchilocaudatus from several localities in Germany and the Netherlands and provided a detailed redescription of the species based on the European type materials. This species has also been reported from Vietnam (Sturhan 2005) and Hungary (Andraasy 1997). In a survey conducted to study nematodes of Pir Naim village, Savadkuh County, Mazandaran province, North of Iran, a population including four females and eight males were extracted from soil of a rice field using tray method during 2020. After preparing the microscopic slides, their morphological and morphometric characteristics were examined and the obtained data of the population fit well to the original description; so, the population was identified as P. anchilocaudatus.

In the spring and summer of 2021, stems and branches of Jand trees (Prosopis cineraria L.) with canker symptoms were collected from the forests of Sahara-Sandy region, Sistan, and Baluchestan province, Iran. Disease incidence was calculated by counting the number of infected trees and part of each tree, ranging from 70 to 100%. Stems and branches with canker symptoms and necrosis were incubated at room temperature in a moist chamber and Water-Agar 2%. After seven days' incubation, black conidia and conidiophores developed. A fungus belonging to the genus Alternaria was isolated from surface-sterilized samples. To identify isolates by morphological criteria, purified cultures were incubated at 23-25°C on Potato Carrot Agar (PCA) medium under 8/16 h light/ dark cycle photoperiod for 5-7 days (Simmons, 2007). Based on morphological characteristics such as colony color, sporulation pattern, sizes of primary and secondary conidiophores, conidia, and surface ornamentation of conidia, isolates were grouped into infectoria sections of Alternaria. On PDA after 7 days, colonies dark with gray aerial mycelia. Conidia were obclavate in long or short chains predominantly with longitudinal septa (Figure 2). The isolate was further identified by sequencing the internal transcribed spacer (ITS) region, glyceraldehyde 3-phosphate dehydrogenase (gpd), and plasma membrane ATPase (ATPase) (White et al. 1990; Berbee et al., 1999). In phylogenetic tree is constructed for the Infectoriae section based on three gene regions (Poursafar et al. 2017; Marin-Felix et al., 2019), the S3BK isolate lied with Alternaria infectoria CBS 210.86, and A. frumenti CBS 119401 in the same clade.