scholarly journals First Report of Powdery Mildew on Euphorbia pekinensis Caused by Podosphaera euphorbiae-helioscopiae in China

Plant Disease ◽  
2011 ◽  
Vol 95 (10) ◽  
pp. 1314-1314
Author(s):  
S. Y. Liu ◽  
L. L. Wang ◽  
W. T. Jiang ◽  
Y. Li
Keyword(s):  
Powdery Mildew ◽  
Perennial Grass ◽  
Morphological Characteristics ◽  
28S Rdna ◽  
Direct Sequence ◽  
Internal Transcribed Spacer Region ◽  
Powdery Mildew Fungi ◽  
Germ Tubes ◽  
Euphorbia Pekinensis Rupr ◽  
Taxonomical Study

Euphorbia pekinensis Rupr, the Peking spurge, is a perennial grass that is planted throughout northeast China. Its roots can be used as a Chinese medicine for diuretic or purgative purposes. Some diterpenoids isolated from Euphorbia spp. show strong antitumor, antivirus, skin-irritating, and tumor-promoting activities. Some species contain chemicals that can be used as pesticides. In September and October 2009, spurge plants were seriously infected by powdery mildew fungi in Changchun Agri-Expon, Jilin Province, China. White mildew colonies appeared in early autumn and initial colonies coalesced to cover the entire upper sides of leaves, stems, and petals 3 to 4 weeks after the disease was noticed. Until late October, chasmothecia were observed on leaves and stems and the infected areas also became dark brown. Mycelium was amphigenous, in patches, white, and persistent. Conidia with distinct fibrosin bodies were ellipsoid-cylindrical, 21.6 to 33.8 × 12 to 15.6 μm, and produced in chains. Germ tubes arose near a pole of the conidia and terminated in simple, unlobed apices. Conidiophores were 59.8 to 139.9 μm; foot cells were straight to slightly flexuous, followed by one to three cells, and 24 to 48 × 8.4 to 10.8 μm. Hyphal appressoria were papillate. Chasmothecia were 70 to 95 μm in diameter, averaging 79.4 μm, and were immersed in mycelia. Mycelioid appendages (5 to 12) occurred in the lower part of the chasmothecia and were flexuous, curved, thick walled, and strongly undulate. Appendages were long (349-) 490 to 1,000 (-1,300) μm, averaging 759.4 μm. They were often densely crowded around the chasmothecia. Asci were single, sessile or short stalked, 60 to 80 × 45 to 70 μm, and eight spored. Ascospores were ellipsoid-ovoid and 16.8 to 28.8 × 10.8 to 18 μm. The fungus was identified as Podosphaera euphorbiae-helioscopiae on the basis of morphological characteristics of the anamorphic and teleomorphic stages. An herbarium specimen was deposited in the Herbarium of Mycology of Jilin Agriculture University (CJLCC100). Genomic DNA was extracted from the chasmothecia, and the internal transcribed spacer region (ITS) and the D1/D2 domains of the 28S rDNA were amplified and sequenced (GenBank Nos. JF795490 and JF795491). The ITS sequence has 98% identity with those of Podosphaera lini, P. macularis, and P. spiraeae, and the D1-D2 sequence of 28S rDNA has 99% identity with those of P. negeri and P. spiraeae, which indicated that this fungus belongs to the genus Podosphaera, even though there is no direct sequence evidence that it is P. euphorbiae-helioscopiae. P. euphorbiae-helioscopiae has only been previously reported in Japan (2), occurring on Euphorbia helioscopia. This species is unique because of the long and curved, thick-walled appendages, and there is no comparable species (1). P. euphorbiae-hirtae and P. euphorbiae are reported to infect Euphorbiaceae plants. Both species differ from P. euphorbiae-helioscopiae in their conspicuously shorter appendages (1,3). To our knowledge, this is the first reported occurrence of powdery mildew on E. pekinensis, and P. euphorbiae-helioscopiae is new to China. This is also the first description of the anamorph of the fungus since there is no record in the Erysiphales Database. References: (1) U. Braun. Nova Hedwigia 89:1, 1987. (2) Y. Nomura. Taxonomical Study of Erysiphaceae of Japan. Yokendo LTD, Tokyo, 1997. (3) R. Y. Zheng and Y. N. Yu. Flora Fungorum Sinicorum. Vol. 1. Erysiphales. Science Press, Beijing, 1987.

scholarly journals Occurrence of Powdery Mildew Caused by Blumeria graminis f. sp. poae on Poa pratensis in China

Plant Disease ◽  
2020 ◽  
Author(s):  
Mo Zhu ◽  
Jie Ji ◽  
Wenqi Shi ◽  
YongFang Li
Keyword(s):  
Powdery Mildew ◽  
Germ Tube ◽  
Poa Pratensis ◽  
Perennial Grass ◽  
Morphological Characteristics ◽  
Signs And Symptoms ◽  
Its Region ◽  
Width Ratio ◽  
Leaf Surfaces ◽  
Length Width

Poa pratensis, known as bluegrass, is a perennial grass and one of the best varieties with highly valued pasture and turf grass uses. It is widely grown on golf courses and used for lawns in squares and parks (Luo et al. 2020). During April and May 2020, powdery mildew-like signs and symptoms were observed on leaves of P. pratensis in Muye Park, Xinxiang city (35.3°N; 113.9°E), Henan Province, China. White or grayish powdery masses in spots- or coalesced lesions were abundant on the adaxial surfaces of leaves and covered up to 90 % of the leaf area. Some of the mildew-infested leaves appeared chlorotic or began senescence. Mildew-infested leaves were collected to microscopically observe the morphological characteristics of this pathogen. Conidiophores were composed of foot cells, followed by one or two cells, and conidia. The ellipsoid- shaped conidia (n = 50) were 25 - 36 × 10 - 15 μm (length × width), on average 30 × 13 μm, with a length/width ratio of 2.3. Foot-cells (n = 15) were 30 - 44 μm long and 7 - 15 μm wide. On leaf surfaces, germinated conidia produced a short primary germ tube and then a long secondary germ tube that finally differentiated into a hooked appressorium. Chasmothecia were not found. Based on these morphological characteristics, the pathogen was initially identified as B. graminis f. sp. poae, the known forma specialis (f. sp.) of B. graminis on P. pratensis (Braun and Cook 2012; Troch et al. 2014). Mycelia of the pathogen were scraped from infected leaves and total genomic DNA was isolated using the method described previously (Zhu et al. 2019). The rDNA internal transcribed spacer (ITS) region was amplified applying primer pairs ITS1/ITS4 (White et al. 1990). The amplicon was cloned and sequenced by Invitrogen (Shanghai, China). The obtained sequence for the pathogen was deposited into GenBank under Accession No. MT892956 and was 100 % identical (549/549 bp) to B. graminis on P. pratensis (AB273530) (Inuma et al. 2007). In addition, the phylogenetic analysis clearly showed that the identified fungus and B. graminis f. sp. poae were clustered in the same branch. To perform pathogenicity analysis, leaf surfaces of eight healthy plants were inoculated by dusting fungal conidia from diseased leaves. Eight non-inoculated plants served as a control. The non-inoculated and inoculated plants were separately maintained in two growth chambers (humidity, 60 %; light/dark, 16 h/8 h; temperature, 18 ℃). Twelve to fourteen days after inoculation, B. graminis signs were visible on inoculated leaves, while control plants remained healthy. The pathogenicity assays were repeated twice and showed same results. Therefore, based on the morphological characteristics and molecular analysis, the pathogen was identified and confirmed as B. graminis f. sp. poae. This pathogen has been reported on P. pratensis in Switzerland and Japan (Inuma et al. 2007). This is, to our best knowledge, the first disease note reporting B. graminis on P. pratensis in China. Because the hybridization of B. graminis formae speciales (ff. spp.). allow the pathogens to adapt to new hosts, P. pratensis may serve as a primary inoculum reservoir of B. graminis to threaten other species, including cereal crops (Klingeman et al. 2018; Menardo et al. 2016). In addition, powdery mildew may negatively affect the yield and quality of grasses. Our report expands the knowledge of B. graminis f. sp. poae and provides the fundamental information for future powdery mildew control.

scholarly journals First Report of Powdery Mildew Caused by Erysiphe diffusa, Oidium neolycopersici, and Podosphaera xanthii on Papaya in Taiwan

Plant Disease ◽  
2011 ◽  
Vol 95 (9) ◽  
pp. 1188-1188 ◽  
Author(s):  
J.-G. Tsay ◽  
R.-S. Chen ◽  
H.-L. Wang ◽  
W.-L. Wang ◽  
B.-C. Weng
Keyword(s):  
Powdery Mildew ◽  
Morphological Characteristics ◽  
Its Region ◽  
Podosphaera Xanthii ◽  
Oidium Neolycopersici ◽  
First Report ◽  
Plastic Bags ◽  
The World ◽  
Golovinomyces Cichoracearum ◽  
Powdery Mildew Fungi

Powdery mildew can be found in most papaya (Carica papaya L.) fields during the winter and spring seasons in Taiwan. It usually causes severe yellowing of the leaf lamina and petiole and serious defoliation. Three types of powdery mildew fungi were isolated from papaya leaves in Chiayi City (23.28°N, 120.28°E) at the beginning of 2008. Conidia of the first one were single, globose, hyaline, and 24 to 36 × 14 to 18 μm (average 30.2 × 15.6 μm) without fibrosin bodies and with straight or occasionally flexuous conidiophores at the base. The second one had short pseudo-chains of two to four conidia which were ellipsoidal to ovoid, hyaline, and 24 to 40 × 12 to 16 μm (average 29.7 × 13.4 μm) without fibrosin bodies. The third type had chains of ellipsoidal conidia that were hyaline, 24 to 28 × 12 to 16 μm (average 26.3 × 14.4 μm) and contained fibrosin bodies. To confirm the identity of the three fungi, the internal transcribed spacer (ITS) region of rDNA was amplified using the primer pairs G1 (5′-TCC GTA GGT GAA CCT GCG GAA GGA T-3′)/Ed2 (5′-CGC GTA GAG CCC ACG TCG GA-3′), G1 (5′-TCC GTA GGT GAA CCT GCG GAA GGA T-3′)/On2 (5′-TGT GAT CCA TGT GAC TGG AA-3′), and S1 (5′-GGA TCA TTA CTG AGC GCG AGG CCC CG-3′)/S2 (5′-CGC CGC CCT GGC GCG AGA TAC A-3′). The alignment of obtained sequences (GenBank Accession Nos. GU358452, 507 bp; GU358451, 580 bp; and GU358450, 455 bp) showed a sequence identity of 100, 99, and 99% with the ITS sequences of Erysiphe diffusa, Oidium neolycopersici, and Podosphaera xanthii (GenBank Accession Nos. FJ378880, EU909694, and GQ927254), respectively. On the basis of morphological characteristics and ITS sequence similarities, these fungi were identified as E. diffusa (Cooke & Peck) U. Braun & S. Takam., O. neolycopersici L. Kiss, and P. xanthii (Castagne) U. Braun & S. Takam., respectively (1,3). Single colonies on papaya leaves infected with powdery mildew were identified in the laboratory and maintained on papaya leaves as inoculum. Pathogenicity was confirmed through inoculations by gently pressing a single colony of each fungus onto leaves of healthy papaya seedlings (cv. Horng-Fe). Five seedlings were inoculated for each fungus and then covered with plastic bags for 2 days. Five noninoculated seedlings served as control. After inoculation, treated plants were maintained separately from the control in different rooms of a greenhouse at 25°C under natural daylight conditions. Seven days after inoculation, typical symptoms of powdery mildew were observed on inoculated plants, but not on noninoculated plants. The same species from diseased lesions following artificial inoculation with each fungus were identified with light microscopy. Papaya was previously described as a host to O. caricae Noack in many tropical and subtropical areas of the world including Taiwan (2). However E. cruciferarum, Golovinomyces cichoracearum, Oidiopsis sicula, O. caricae, O. caricae-papayae, O. caricicola, O. indicum, O. papayae, Ovulariopsis papayae, P. caricae-papayae, P. macularis, P. xanthii, and Streptopodium caricae were reported to infect papaya (4). To our knowledge, this is the first report of papaya powdery mildew caused by E. diffusa and O. neolycopersici in the world and the first report of the three fungi found on papaya in Taiwan. References: (1) U. Braun and S. Takamatsu. Schlechtendalia 4:1, 2000. (2) H. S. Chien and H. L. Wang. J. Agric. Res. China 33:320, 1984. (3) L. Kiss et al. Mycol. Res. 105:684, 2001. (4) J. R. Liberato et al. Mycol. Res. 108:1185, 2004.

scholarly journals First Report of Sawadaea polyfida Causing Powdery Mildew of Acer palmatum in China

Plant Disease ◽  
2021 ◽  
Author(s):  
Yu Wan ◽  
Yuan-Zhi Si ◽  
Yang-Chun-Zi Liao ◽  
Li-Hua Zhu
Keyword(s):  
Powdery Mildew ◽  
Phylogenetic Analyses ◽  
Morphological Characteristics ◽  
Signs And Symptoms ◽  
Species Identity ◽  
Internal Transcribed Spacer Region ◽  
Voucher Specimen ◽  
First Report ◽  
Effective Strategies ◽  
And Control

Acer palmatum Thunb. is an important colorful leaf ornamental tree species widely distributed in Japan, Korea and China (Carlos et al. 2016). In October 2019, powdery mildew was observed on leaves of A. palmatum planted at Qixia Mountain Park and the campus of Nanjing Forestry University, Nanjing, Jiangsu, China. The powdery mildew infected and colonized leaves, covering both leaf surfaces with white mycelia, giving affected plants an unsightly appearance. Nearly 17.4% of the plants (87/501) exhibited these signs and symptoms. Fresh specimens were collected and examined for the identification of the pathogen. Photos were taken with a ZEISS Axio Imager A2m microscope and a scanning electronic microscope. Chasmothecia were scattered or aggregated on the upper and lower surfaces of the leaves, blackish brown, oblate, 157.5 to 238.1 × 152.3 to 217.8 μm (n=30), with numerous appendages (100 to 200). Appendages were often (1−) 2 to 3 times branched from the middle of the stalk, uncinate to circinate at the apex, hyaline, aseptate, 30.0 to 70.8 × 4.1 to 8.2 μm (n=30). Asci were 11 to 21 per chasmothecium (n=30), long oval, oval, oblong, with short stalk or sessile, 80.6 ± 8.6 × 40.3 ± 4.0 um (n=30) in length, 6 to 8 spored (n=30). Ascospores were ovoid, 18.2 ± 1.6 × 11.1 ± 1.2 μm (n=30). Microconidiophores were 25 to 50 × 4.0 to 5.5 μm, producing microconidia in chains. Microconidia were ellipsoidal, subglobose, 8.7 ± 0.6 × 7.2 ± 0.6 μm (n=30). Macroconidia were not observed. Based on the morphological characteristics, the fungus was identified as Sawadaea polyfida (C.T. Wei) R.Y. Zheng & G. Q. Chen (Zheng and Yu 1987). To confirm the causative species identity, a representative voucher specimen collected and deposited at Nanjing Forestry University was used for a molecular analysis. Mycelia and conidia were collected from diseased leaves and genomic DNA of the pathogen was extracted and the internal transcribed spacer region (ITS) was amplified with primers ITS1/ITS4 (White et al. 1990). The resulting sequence of 461 bp was deposited in GenBank (accession no. MW255383). BLAST result showed that this sequence fully agreed with a sequence of S. polyfida [AB193381.1 (ITS), identities = 461/461 (100%)]. A maximum likelihood phylogenetic analyses using IQtree v. 1.6.8 with the ITS sequence placed this fungus in the S. polyfida clade. Based on the morphology and phylogeny, the fungus was identified as S. polyfida (Hirose et al. 2005; Zheng and Yu 1987). Pathogenicity was tested through inoculation by gently pressing the naturally infected leaves onto healthy ones of three potted A. palmatum seedlings wih five leaves. Healthy leaves from three other seedlings served as control. Inoculated and control seedlings were placed in separate growth chambers maintained at 20 ± 2°C, 70% humidity, with a 16 h/8 h light/dark period. Symptoms developed 8 days after inoculation. The powdery mildew developing on the inoculated seedlings was sequenced and confirmed as S. polyfida. The control leaves did not develop powdery mildew. S. polyfida has been reported on Acer catalpifolium in China (Zheng and Chen 1980), A. amoenum, A. australe, A. japonicum, A. palmatum, A. shirasawanum, and A. sieboldianum in Japan (Hirose et al. 2005; Meeboonet al. 2015), as well as A. takesimense in Korea (Lee et al. 2011). To the best of our knowledge, this is the first report of powdery mildew caused by S. polyfida on A. palmatum in China. These results form the basis for developing effective strategies for monitoring and managing this disease.

scholarly journals First Report of Powdery Mildew on Heath Aster Caused by Erysiphe cichoracearum in Argentina

Plant Disease ◽  
2000 ◽  
Vol 84 (9) ◽  
pp. 1044-1044
Author(s):  
S. Wolcan ◽  
L. Ronco
Keyword(s):  
Powdery Mildew ◽  
Buenos Aires ◽  
Morphological Characteristics ◽  
Buenos Aires Province ◽  
Abaxial Surface ◽  
Basal Ring ◽  
First Report ◽  
Erysiphe Cichoracearum ◽  
Aster Ericoides ◽  
Germ Tubes

In 1995, powdery mildew was observed on commercial greenhousegrown Aster ericoides L. from La Plata, Buenos Aires Province. The disease affected about 95% of the growers. Mildew first appeared as white circular patches on the adaxial surface of leaves. As disease progressed, the abaxial surface of leaves, petioles, stems, and calyces were covered by cottony masses of mycelium and conidia, and basal leaves later wilted and died. Young plants (4 to 5 leaves) through flowering plants were affected. Conidia were ovoid-cylindrical, often slightly constricted at the ends, and were produced in chains on unbranched conidiophores. Conidia lacked fibrosin bodies and ranged from 30 to 41 μm × 10 to 19 μm. Long unbranched germ tubes were formed from the ends of conidia. The morphological characteristics of the fungus fit those described for Erysiphe cichoracearum DC (1). In addition, the perfect stage was found on older tissues. Subglobose, dark brown cleistothecia (105 to 210 μm in diameter) with a basal ring of myceloid appendages were observed. Cleistothecia contained multiple ellipsoid asci (48 to 69 μm × 30 to 37 μm) with two hyaline, one-celled, ellipsoid ascospores (22 to 26 μm × 11 to 15 μm). Pathogenicity was tested by pressing diseased leaves onto healthy leaves of aster cv. Sunset and incubating plants in humidity chambers for 48 h. The powdery mildew that developed was morphologically identical to the original isolate. This is the first report of E. cichoracearum on heath aster in Argentina. Reference: (1) H. J. Boesewinkel. Bot. Rev. 46:167, 1980.

scholarly journals First Report of Powdery Mildew Caused by Erysiphe macleayae on Torenia fournieri in China

Plant Disease ◽  
2014 ◽  
Vol 98 (9) ◽  
pp. 1277-1277 ◽  
Author(s):  
X.-Y. Men ◽  
S.-Y. Liu ◽  
W.-T. Jiang ◽  
Y. Li
Keyword(s):  
Powdery Mildew ◽  
Morphological Characteristics ◽  
Its Region ◽  
Chelidonium Majus ◽  
Torenia Fournieri ◽  
Chinese Medicinal Herb ◽  
First Report ◽  
Advanced Stages ◽  
Voucher Specimens ◽  
Germ Tubes

Torenia fournieri (Linderniaceae) is a common ornamental plant in China. It is also an important Chinese medicinal herb for its heart clearing and toxin removal properties. In October 2013, severe powdery mildew infections were observed on T. fournieri in Baihuayuan Garden (125.35°E, 43.88°N), China. Voucher specimens were deposited in the Herbarium of Mycology of Jilin Agricultural University under the accession number HMJAU02176. Whitish colonies covered the surface of leaves, petioles, sepals, and stems. The infected leaves became yellow and necrotic by advanced stages of the infection. Chasmothecia with a diameter between 63.5 and 95 μm were present singly or in groups, and bore dark brown mycelioid. The appendages were 0.5 to 4 times as long as the chasmothecial diameter, brown at the base and paler toward the apex. Asci were 2 to 6 per chasmothecium, short-stalked or sessile, 50 to 62 × 30 to 50.5 μm, and 2- to 4-spored. Ascospores were pale brown, oval to ellipsoid, 27 to 43 × 13 to 17 μm. Hyphae were flexuous to straight, branched, and septate. Appressoria were well-developed, lobed, and solitary or in opposite pairs. Conidiophores were unbranched, cylindrical, and 94 to 185 × 9 to 15 μm. Foot-cells were straight, cylindrical, 19 to 40 μm long, and followed by 1 to 3 cells shorter or nearly equal to the foot-cell. Conidia were singly produced, cylindrical or oval, 34 to 44 × 16 to 20 μm, and without distinct fibrosin bodies. Lobed germ tubes were produced at the tip of conidia. The morphological characteristics of sexual and asexual structures were consistent with Erysiphe macleayae (1,2). To confirm the identification, the complete internal transcribed spacer (ITS) region of rDNA of the pathogen was amplified with the primers ITS1/ITS4 and sequenced (3). The resulting 574-bp sequence (KJ600796) showed 100% similarity with E. macleayae (KF856294) and Oidium sp. isolated from Chelidonium majus (HQ286645 to 46) and one base different from M. microcarpa (JQ681217). Koch's postulate was completed by gently pressing a diseased leaf onto three young excised leaves of asymptomatic seedlings. Three non-inoculated leaves were used as controls. Inoculated leaves were incubated in separate petri dishes in a greenhouse at 20 to 25°C. Symptoms developed 5 days after inoculation, whereas the control leaves remained symptomless (voucher specimens HMJAU02176I). The morphology of the fungus on the inoculated leaves was identical to that observed on the originally diseased leaves. Powdery mildew on T. fournieri has only been reported as Golovinomyces sp. in Hungary (4). To our knowledge, this is the first report of powdery mildew caused by E. macleayae on T. fournieri worldwide. Infection of Torenia by E. macleayae, a common powdery mildew on various hosts of the Papaveraceae, is very unusual and unexpected. It demonstrates a wider host range of this species beyond the limits of the Papaveraceae. References: (1) U. Braun and R. T. A. Cook. Taxonomic manual of the Erysiphales (Powdery Mildews), CBS Biodiversity Series 11. CBS, Utrecht, the Netherlands, 2012. (2) M. J. Park et al. Plant Dis. 96:1376, 2012. (3) S. Takamatsu et al. Mycol. Res. 113:117, 2009. (4) P. Vági et al. Eur. J. Plant Pathol. 117:89, 2007.

scholarly journals First Report of Powdery Mildew Caused by Blumeria graminis on Poa pratensis var. anceps Gaud cv. Qinghai in China

Plant Disease ◽  
2021 ◽  
Author(s):  
Gensheng Bao ◽  
Xiaoxing Wei ◽  
Wenhui Liu
Keyword(s):  
Powdery Mildew ◽  
Poa Pratensis ◽  
Sequence Similarity ◽  
Perennial Grass ◽  
Morphological Characteristics ◽  
Blumeria Graminis ◽  
Tibet Plateau ◽  
Large Area ◽  
Adaxial Surface ◽  
First Report

Poa pratensis, an important cool-season perennial grass, is widely cultivated for construction of grasslands and ecological management of Qinghai-Tibet Plateau (Dong et al. 2020). Poa pratensis var. anceps Gaud cv. Qinghai (PPAQ) is a variant of P. pratensis (Liu et al. 2009). In June 2016, powdery mildew was observed on PPAQ in an artificial field of PPAQ in Haiyan county of Haibei Tibetan Autonomous Prefecture, Qinghai province, China (36°59′17.76″N, 100°52′54.01″E). Approximately 30 to 50% of leaves (approximate 10 ha) were affected. Initially, irregular white mycelial colonies were observed on the adaxial surface of affected leaves. The colonies increased in number and size, and later covered a large area of leaves and stems. In advanced stages of disease, the colonies covered the whole adaxial surface and white patches appeared on the abaxial surface of affected leaves, and eventually caused leaf death. Conidiophores were unbranched, measuring 160 to 235 × 4 to 13 μm, and borne vertically on hyphae. Each conidiophore produced 4 to 11 conidia in a chain. The conidia were oval, one-celled, and hyaline, measuring 22 to 40 ×10 to 21 μm (n = 50). Chasmothecia were yellow, spherical, and 172 to 240 μm in diameter (n = 20), each of which contained 8 to 17 asci. The appendages were few, and hyphoid. Asci were oblong or ovate, measuring 79 to 115 × 31 to 45 μm (n = 20). Asci were petiolate, containing eight ascospores. Ascospores were round to oval, colorless, one-celled, measuring 17 to 33 × 8 to 14 μm (n = 50). Based on morphological characteristics, the fungal organism was identified as Blumeria graminis (DC.) Speer. To confirm the identification, the internal transcribed spacer (ITS) of 612 bp was amplified from DNA of conidia using ITS5 and P3 primers (Takamatsu et al. 2009). The ITS sequence was deposited in GenBank database (Accession No. MF429949). The ITS showed 95% sequence similarity with those of B. graminis on Poa nemoralis in USA (Accession No. AB273560) and on P. bullbosa in Iran (Accession No. AB273551) (Inuma et al. 2007). Five two-month-old healthy plants were inoculated by spraying a spore suspension (1× 105 conidia ml-1) prepared from conidia brushed from infected plants; five plants sprayed with sterile distilled water served as controls. All the plants were maintained in a growth chamber with a constant temperature of 20°C, a 12 h/12 h light/dark diurnal cycle, and 70% humidity. Two weeks after inoculation, symptoms of powdery mildew were observed on all inoculated plants, whereas the control plants remained symptomless. The same fungus was confirmed by morphological characterization and molecular assays as described above. B. graminis has been reported on P. pratensis in USA (Dugan and Newcombe 2007), Israel (Voytyuk et al. 2009), and China (Zhang et al. 2014), but has not previously been reported on PPAQ. As far as we know, this is the first report of powdery mildew caused by B. graminis on PPAQ in China. These findings indicated that the health of PPAQ was substantially threaten when infected by powdery mildew, therefore, our results also contributed some valuable information how to diagnose this disease on PPAQ in China.

scholarly journals First Report of Brown Rot of fruit on Vitis amurensis Caused by Monilinia polystroma in China

Plant Disease ◽  
2021 ◽  
Author(s):  
Yue Wang ◽  
Yiming Yang ◽  
Shutian Fan ◽  
Wenpeng Lu
Keyword(s):  
Russian Far East ◽  
Morphological Characteristics ◽  
Brown Rot ◽  
Effective Control ◽  
Vitis Amurensis ◽  
Conidial Suspension ◽  
Sterile Water ◽  
Internal Transcribed Spacer Region ◽  
First Report ◽  
Germ Tubes

Vitis amurensis Rupr. (Amur grape) is a wild grape genetic resource widely distributed in Heilongjiang, Jilin, Liaoning, and Inner Mongolia, among other places in China (Song et al. 2009) and the Russian Far East and Korean Peninsula. In September 2018, brown rot symptoms were observed at ripening stage on the fruits of a 5-year-old Amur grapevine germplasm resources nursery of the cultivar ‘Beibinghong’ and a few Russian resources in Zuojia Town, Jilin City, Jilin Province, China. The diseased fruit surface became brown with soft rot and produced buff to brownish-grey sporodochia with conidia. Around 180 plants of ‘Beibinghong’ were examined which had 8 % incidence. Forty five samples were collected from symptomatic fruits of 15 randomly sampled ‘Beibinghong’ grape clusters, cut into 5-mm2 pieces of diseased tissue, surface sterilized with 1% NaOCl for 2 min, rinsed three times with sterile water, dried on sterilized filter paper, and plated on potato dextrose agar (PDA). Thirteen monosporic isolates were obtained using the single-spore isolation method with incubation at 25°C and a 12-h light/12-h dark cycle. The average colony diameter was 46–49 mm after 4 days of culture on PDA. Colonies were white to grayish with even margins. Irregular black stromatal crusts were observed on the reverse side of dishes 10 days after inoculation. Conidial spores were produced when cultured on cherry agar at 25°C under near-ultravolet light. Spores were single-celled and hyaline, limoniform or ellipsoid, and were produced in branched monilioid chains, 12–22 × 8–13 µm (mean: 15.4 ± 1.03 × 9.01 ± 0.72 µm, n = 50). When conidia were cultured on water agar at 25°C for 18 h, the germ tubes were straight, 700–1,000 µm long, and often with two germ tubes per conidium. Morphological characteristics were consistent with those of Monilinia polystroma (van Leeuwen et al. 2002). To confirm the species identification, two DNA regions of the selected isolate ‘VAMPWYZSH8’ were amplified by polymerase chain reaction (PCR) and sequenced: the internal transcribed spacer region (ITS) was generated using primers ITS1/ ITS4 (Munda 2015) and β-tubulin (TUB2) was amplified using primers Bt2a/Bt2b (Zhu et al. 2016). A BLAST analysis of the nucleotide sequence of the PCR products revealed 100% identity with two M. polystroma sequences in the NCBI GenBank (KJ814976 for ITS, KR778970 for TUB2). Our sequences were deposited in GenBank with accession nos. MT038413 for ITS and MT038414 for TUB2. On the basis of these results, the isolate was identified as M. polystroma. To confirm pathogenicity, 78 fresh and healthy bunches of ‘Beibinghong’ grapes at ripening were collected, surface disinfected by immersion in 1% NaOCl for 1 min, rinsed three times with sterile water, then allowed to air dry. Under dry aseptic conditions, the fruits were inoculated using the pin prick method. Each wound was inoculated with 10 μl conidial suspension (106 spore ml−1) and incubated at 25°C with about 90% relative humidity and natural light. Inoculation with water was used as control and the experiment was repeated three times. After a 10-day incubation, typical symptoms of brown rot developed on inoculated fruits, while control fruits were symptomless. The fungus was consistently re-isolated only from diseased fruits and showed the same morphological characteristics as the original isolates, thus fulfilling Koch’s postulates. This is the first report of M. polystroma on V. amurensis in China. The resulting disease decreases fruit quality and yield, necessitating the development of effective control measures.

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