Tranzschelia Discolor Research Articles

First Report of Rust Caused by Tranzschelia discolor on Peach Leaves in Shenzhou, China.

Peach (Prunus persica [L.] Batsch) as an economically important fruit tree is widely cultivated in Shenzhou, China. In September 2021, peach rust was observed in the peach tree in Shenzhou City, Hebei Province (lat. 38°02'56'' N, long. 115°54'57'' E, altitude 22 m). We investigated a peach orchard with a planting area of 1334 m2, where a total of 162 peach trees were planted, and found that about 10% of peach trees exhibited severe disease symptoms. The leaves of infected plant developed 100% disease symptoms, in which 50% of the infected leaves showed about 10 small pale-yellow spots on the front of leaves and reddish-brown pustules on the corresponding abaxial surface of leaves. Urediniospores varied from obovoid to clavate in shape, sometimes in irregular shape. They were orange-brown, echinulate near base with spines smaller towards apex and often smooth at apex, with germ pores 3-4 at equator, size ranging from 25.4 to 38.6 × 10.1 to 18.7 µm (n=100), and with wall 1 to 1.5μm thick at sides and 5-7 μm thick at apex. Golden capitate paraphyses were present, ranging from 25 to 40 µm in length, with a head in diameter of 12 to 14 µm and a tail in width of 5.2 to 6.5 µm. Based on the rust morphological characters, this pathogen was primarily identified as Tranzschelia discolor (Fuckel) Tranzschel & Litv. (Hiratsuka et al. 1992). For molecular identification, total DNA was extracted from 2 isolates, respectively, and the internal transcribed spacer (ITS) region was PCR-amplified using the primer set ITS5-u and ITS4-u (Pfunder et al. 2001). Obtained sequences were compared with sequences in the GenBank repository using BLAST algorithm. BLAST showed a 100% sequence identify to T. discolor (accession nos. AB097449、MT786217、KU712078、KY764179、MH599069). The sequence has been deposited in GenBank with (accession NO. ON950745 and ON950747). Thus, combining morphological observations and molecular identification, the isolate was identified as T. discolor. The pathogenicity was verified by inoculating the abaxial surface of peach leaves with a suspension of 1 × 106 urediniospores/ml. Peach leaves sprayed with sterile water were used as controls. The inoculated peach trees were placed in a greenhouse at 20°C under dark for 24 hours and maintained at 100% relative humidity to promote disease development. Next, the peach trees were grown in a greenhouse at 20°C with a 12 h day length and symptoms were observed on the leaves 14 days after inoculation. In contrast, the control leaves were asymptomatic. Previous studies reported that peach rust occurred in Oman, Korea and Brazil was caused by T. discolor. (Deadman M L, et al.2007, Shin, H D, et al. 2019, Vidal G S, et al. 2021). To our knowledge, this is the first report of T. discolor as a causal agent causing peach leaf rust in Northern China, which will enable us to rapidly diagnose this disease, identify the occurrence of this disease and develop adequate management strategies to control it in China.

A molecular approach reveals Tranzschelia discolor as the causal agent of rust on plum and peach in Brazil.

Plum and peach are important crops in the southernmost regions of Brazil and in the majority, fresh fruit producers are small producers, which guarantee their family income. Tranzschelia discolor and T. pruni-spinosae are the etiological agents of rust on Prunus domestica (plum) and P. persica (peach) in Brazil (Mendes and Urben, 2020). The molecular characterization of Tranzschelia specimens revealed different clades that are not attributed to known species, showing the need for taxonomic evaluation of Tranzschelia species in the tropics (Scholler et al. 2014; 2019). As Tranzschelia species reported in Brazil were identified only by morphological characteristics, this study aimed to carry out a survey to verify the etiology of rust on plum and peach based on molecular data. In 2018, rust symptoms in peach and plum trees were observed with maximum severity of 30% and 35%, respectively, in three Brazilian states. Symptoms of plum and peach rust are yellowish-green spots visible on the adaxial side of the leaves and uredia/uredinial sori releasing the brown urediniospores on the abaxial side (Supplementary figure 1). Symptomatic leaves of plum and peach were collected at Curitiba in the states of Paraná (lat. 25°25'47" S and long. 49°16'19" W, altitude of 935 meters) in a research station, Videira in Santa Catarina (lat. 27°00'30" S and long. 51°09'06" W, altitude of 750 meters) in a research station and Paranapanema in São Paulo (lat. 23º23'19" S and long. 48º43'22" W, altitude of 610 meters) in a farmer field, and deposited in the herbarium of the Municipal Botanical Museum of Curitiba (MBM 429790 to 429795). Urediniospores collected on plum and peach leaves were all echinulate, obovoid, orange-brown, and measured 18.0 - 33.5 μm × 10.5 - 20.5 μm (n=150) and 22.5 - 40.0 μm × 11.5 - 20.5 μm (n=150), respectively. The genomic DNA of the urediniospores was extracted for amplification and sequencing of the internal transcribed spacer region (ITS) using primers ITS5-u and ITS4-u (Pfunder et al. 2001). The sequences were deposited (Accession Nos. MT786213 to MT786218) and compared to sequences in the GenBank repository using the BLASTn algorithm. The sequences of ITS showed a high percentage of identity (>99%) with sequences from T. discolor (Accession Nos. AB097449, EU014071, KU712078, KY764179, MH599069, MN545867, DQ995341, DQ354542, and KX985768). Additionally, our isolates clustered with others T. discolor in a Bayesian phylogenetic tree based on ITS sequences (study S26663 deposited in TreeBASE) (Supplementary figure 2). A pathogenicity test was carried out on plants by inoculation of a 1.5 × 105 urediniospores mL-1 suspension on the abaxial side of the leaves. Leaves sprayed with sterile water were used as controls. The plants were incubated in a growth chamber (GC) in the dark for 48 h at 23 °C and maintained with 100% RH to establish infections. The inoculated plants were afterwards kept in the GC at a photoperiod of 12 h under same conditions until 14 days when the symptoms and pathogen structures were observed to all six isolates. Control leaves remained symptomless. Tranzschelia discolor infect plants in the genus Prunus, including almond, apricot, nectarine, cherry, peach, and plum (Farr and Rossman 2021). As T. pruni-spinosae was not found, T. discolor is probably the prevalent species in the main regions of Brazil. This information reveals T. discolor as the causal agent of plum and peach rust in Brazil and helps to understand the distribution of this disease in tropics or worldwide.

Intensidade de poda verde em pessegueiro para controle da ferrugem Tranzschelia discolor (Fuckel) Tranzschel e Litvinov

Com o objetivo de se avaliar o controle da ferrugem [Tranzschelia discolor (Fuckel) Tranzschel e Litvinov] em pessegueiro 'Flordaprince' [Prunus persica (L.) Batsch], duas intensidades de poda verde foram realizadas aos 45 dias após a colheita: poda leve e poda de renovação. O experimento foi realizado em condições de campo, no Departamento de Produção Vegetal da ESALQ-USP, em Piracicaba-SP, entre novembro de 2004 e janeiro de 2005. O delineamento experimental adotado foi inteiramente ao acaso, com dois tratamentos e doze réplicas. A parcela experimental correspondeu a duas plantas em espaçamento 3,0 x 1,2 m e conduzidas sob sistema de líder central. A avaliação de incidência e severidade de ferrugem foi realizada em folhas de quatro brotações por parcela, sendo duas por planta. As avaliações foram conduzidas de 33 a 81 dias após a poda verde, em intervalos de sete dias, utilizando-se de escala diagramática adaptada para a ferrugem. Os dados referentes à incidência e severidade de ferrugem foram submetidos, respectivamente, ao teste exato de Fisher e ao teste de Wilcoxon. A incidência e a severidade de ferrugem aumentaram com a idade das folhas, independentemente do tipo de poda verde empregada, atingindo, respectivamente, 81,95% das folhas e 1,43% de área foliar lesionada, aos 81 dias após a poda verde. A poda de renovação não reduziu os níveis de ferrugem em pessegueiro 'Flordaprince' em relação à poda leve, a partir dos 40 dias após a poda verde.

FOURTEEN RUSTS FROM NORTHEAST IRAN

Surveys of fields, parks, and forests in the Golestan province of northeast Iran resulted in the record of fourteen rust-induced diseases on weeping willow, black poplar, blackberry, rose, estragon, garlic, wild oat, barley, ryegrass, wheat, peach, plum, alfalfa, and broad bean. Causal agents were identified as Melampsora coleosporioides, M. allii-populina, Phragmidium bulbosum, Ph. violaceum, Ph. rosae-pimpinellifoliae, Ph. tuberculatum, Puccinia absinthii, P. allii, P. coronata f.sp. avenae, P. coronata f.sp. hordei, P. graminis f.sp. avenae, P. hordei, P. persistens subsp. triticina, Tranzschelia discolor, Uromyces striatus, and U. viciae-fabae. Weeping willow rust and barley crown rust are reported for the first time from Iran and Asia, respectively.

First Report of Rust Caused by Tranzschelia discolor on Peach in Oman

Peach (Prunus persica L.) is the primary fruit crop in parts of the northern mountainous regions of Oman. Local cultivars, propagated by seedling, are used to produce fruit for local markets and shade fodder crops planted underneath the peach canopy. In February of 2006, leaf samples showing rust signs and symptoms were collected from Balad Seet, 120 km southwest of Muscat. Angular, yellow spots were observed on leaf upper surfaces with orange sori on the undersides. The disease was observed to be affecting almost 100% of trees, with many leaves having more than 10 sori per leaf. Lesions producing urediniospores were also observed on twigs where spring growth had cracked. Urediniospores typical of Tranzschelia discolor (Fuckel) Tranzschel & M.A. Litv. were obovoid, echinulate, orange-brown, and measured on average 13 to 17 × 26 to 37 μm, with the cell wall 1.3 to 1.8 μm thick at the sides and as much as 5.8 μm thick at the apex. Golden capitate paraphyses were also present, measuring on average 35 to 57 μm long, head 13 to 16 μm in diameter, and tail 4.9 to 6.7 μm wide. Teliospores were not observed because of the time of year of collection. Pathogen identity was confirmed by analysis of a nuclear rDNA sequence spanning from the 5.8S through the ITS-2 into the first 1,000 bp of the 28S gene (1). A voucher specimen was deposited in the U.S. National Fungus Collection (BPI 875341). The voucher's rDNA sequence deposited in GenBank (Accession No. DQ995341) shared 100% sequence similarity with T. discolor (Accession No. DQ354542). Although T. discolor has a worldwide distribution (2), it has not previously been reported from Oman. Improving the quality of peach production in Oman is an agricultural priority because it boosts the economy of smallscale farms in the mountainous regions. This work will facilitate the current research aimed at evaluating cultivar response to rust disease.

Metodologias de preparação de amostras de ferrugem para estudos morfológicos de urediniósporos por meio de microscopia eletrônica de varredura

Amostras de urediniósporos de ferrugens das espécies Melampsora epitea Thum., Melampsora medusae Thuem., Hemileia vastatrix Berk., Uromyces appendiculatum Pers., Puccinia sorghi Schwein., Tranzschelia discolor Fuckel e Phakopsora euvitis Ono, coletadas dos hospedeiros, chorão (Salix sp.), álamo (Populus deltoides Bartr. Ex. Marsh), cafeeiro (Coffea arabica L.), feijoeiro (Phaseolus vulgaris L.), milho (Zea mays L.), pessegueiro (Prunus persicae L.) e videira (Vitis vinifera L.) respectivamente, foram processadas de 3 formas: a) método convencional (fixação em glutaraldeído e tetróxido de ósmio, desidratação em acetona e secagem ao ponto crítico); b) método do vapor de ósmio e metalização com ouro; c) metalização direta de amostras (utilizado para esporos soltos). A técnica de fratura de amostra congelada em nitrogênio líquido também foi testada para o estudo do interior de pústulas da ferrugem da videira (P. euvitis). As amostras foram visualizadas em microscópio eletrônico de varredura no NAP/MEPA da ESALQ/USP. Procedeu-se à mensuração dos esporos e as imagens obtidas foram capturadas pelo software LeoUserInterface e processadas utilizando-se o programa de computador "Corel Draw". Em todos os métodos analisados obteve-se uma boa preservação da estrutura possibilitando imagens de alta qualidade. No entanto, para esporos livres (mantidos em cápsula de gelatina) o método da metalização direta foi mais prático e rápido. Para observação das pústulas em tecido vegetal os dois métodos de processamento de amostras avaliados proporcionaram resultados satisfatórios. A técnica de fratura em nitrogênio líquido também permitiu perfeita visualização do interior das pústulas da ferrugem da videira.

Initial Infection and Colonization of Leaves and Stems of Cling Peach by Tranzschelia discolor

ABSTRACT Initial infection processes and the subsequent colonization of leaves and young stems of peach by Tranzschelia discolor were studied. On leaves where multiple disease cycles of peach rust occur during the growing season, urediniospores germinated after 4 h of wetness. Germ tubes became septate and formed appressoria only over leaf stomata beginning 18 h after inoculation. No appressoria, however, formed over stomata of positive replicas of leaf surfaces indicating nonthigmotropic responses of germ tubes. On young, primary-growth stems (ca. 8 weeks old), stomata were mostly closed, less frequent than on leaves, and recessed from the surface of the cuticle of the epidermis. Although appressoria formation was not observed on inoculated stems, germ tube growth of urediniospores was directional toward stomata. Penetration of stem tissue is apparently a less common event that was reflected by a lower occurrence of stem lesions compared with that of leaf lesions in our potted plant inoculation studies and previous field observations. Still, stem lesions are important as sources of primary inoculum each spring and were reproduced in this study for the first time. Fungal colonization of leaves and stems was subepidermal-intercellular and haustoria were commonly found within mesophyll or cortical cells, respectively. No fungal colonization was observed in cambial stem tissue. Vascular tissue was also not colonized and delimited lesions in leaves and stems. Morphological host responses were not observed in infections on either leaves or young stems. In older stems (>32 weeks old), however, the infection was delimited by a wound periderm after uredinial formation. Furthermore, with continued secondary growth, stems recovered and fungal lesions became part of the bark tissue of woody branches. Thus, the fungus must infect primary-growth branches each year to establish stem lesions.

An annotated list of Urediniomycetes (rust fungi) from South Africa 1: Melampsoraceae and Pucciniaceae, excluding <i>Puccinia</i> and <i>Uromyce</i>s

Up-to-date information is given on the identity, occurrence, nomenclature, host ranges, geographical distribution and literature references of the Urediniomycetes in South Africa. Species of the family Melampsoraceae and all species of the family Pucciniaceae other than those in the genera Puccinia Pers. and Uromyces (Link) Unger are listed. New species records since 1945 include the following: Melampsora allii-populirui Kleb.. Melampsora coleosporioides Dietel. Melampsora laricipopulina Kleb.. Melampsora medusae Thiim., Frommea obtusa-duchesneae (Arthur) Arthur. Hemileia gardeniae-thunbergiae Maubl. Roger. Phakopsora gossypii (Arthur) Hirats. F. Uromycladium tepperianum (Sacc.) McAlpine and Tranzschelia discolor (Fuckel) Tranzschel M.A. Litv. Although many species of rusts have already been recorded, these are thought to represent only a small percentage of the rust population in southern Africa. Furthermore, only a small portion of rust specimens at present housed at PREM have so far been studied. Continued research on this economically important group of fungi is therefore essential.

Incidência de ferrugem em folhas de pessegueiro e nectarineira do germoplasma IAC

Avaliou-se, em fins do verão de 1993, o grau de incidência da ferrugem (Tranzschelia discolor f. sp. domesticae), em dezoito seleções IAC de pessegueiro e seis de nectarineira, mantidos em lote de germoplasma na Estação Experimental de Jundiaí (23°08'S; 46°55'W). A porcentagem de incidência do patógeno foi estimada através de observações macroscópicas das folhas, atribuindo-se notas de 1 a 5 (1 = nula, 2 = leve, 3 = moderada, 4 = severa, 5 = muito severa), conforme o grau da severidade do sintoma. Todo o material pesquisado mostrou-se suceptível ao patógeno, entretanto, as seleções apresentaram sensíveis variações em graus de susceptibilidade. As seleções com maior tolerância ao patógeno foram: 1) pêssegos 'Régis' e IAC 4685-45 e 2) nectarinas 'Josefina' e IAC N 2680-91.

Overwintering of Tranzchelia discolor in prune orchards in New South Wales

There are several ways in which Tranzschelia discolor may overwinter in prune orchards in the Murrumbidgee Irrigation Areas of New South Wales. The aecial state, cross-infection from peach and almond, twig cankers, and urediniospores on living leaves persisting through winter were considered, but were thought to be unlikely. The ability of urediniospores to survive on infected leaf litter, either on the ground under trees or lodged within the framework of trees, was studied over two winters. Urediniospore viability declined with time, but in both seasons a proportion were capable of germination in the spring. Spores exposed within the tree framework survived better than those exposed on the ground, with about 20% and less than 5% respectively remaining viable by spring. In both winters spores from litter which overwintered within the framework of the tree were able to infect prune leaves in the spring. The infectivity of spores exposed on the ground was tested in the spring of one year and infections resulted on inoculated plants. The implications of these findings for the control of the rust in prunes are discussed.

Evaluation of fungicides for curative activity against Tranzschelia discolor, cause of the rust disease of French prune (Prunus domestica L.)

The ergosterol biosynthesis inhibitors, propiconazole, RH-2161 and RH-3866, exhibited strong curative activity against Tranzschelia discolor infections in French prune leaves. Foliar sprays (25-50 ppm) applied during the latent period, up to 7 days after inoculation, completely suppressed the disease. When these fungicides were applied after the appearance of symptoms, they inhibited further lesion growth and sporulation. Other fungicides having some curative activity were triforine and oxycarboxin. Fungicides with little or no curative activity against T. discolor were bitertanol, PP969, triadimefon and tridemorph.