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Oxidation-responsive PEG-b-PVBMS vesicles were prepared via RAFT-mediated PISA of VBMS in ethanol/water, and their sequential oxidation-induced order–disorder–order multiple-phase transitions were reported.

Pearl plum (Prunus salicina Lindl.) is mainly cultivated in Tian’e County in Guangxi Province, southern China. Anthracnose is a devastating disease on pearl plum, causing extensive leaf blight. Diseased leaves were sampled from 21 orchards in Tian’e County. Isolates were first screened for ones resembling Colletotrichum, and 21 representative isolates were selected for sequencing of portions of the ribosomal internal transcribed spacer (ITS), the intergenic region of apn2 and MAT1-2-1 genes (ApMAT), actin (ACT), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), calmodulin (CAL), chitin synthase (CHS-1), and β-tubulin 2 (TUB2). Based on colony, conidial, and appressorial morphology and sequence analyses, the Colletotrichum isolates associated with pearl plum anthracnose were identified as four species: Colletotrichum fructicola (16 isolates), C. gloeosporioides (3 isolates), C. cigarro (1 isolate), and C. siamense (1 isolate). The results of pathogenicity tests showed that isolates of all four species were pathogenic to wounded leaves of pearl plum seedlings. In this study, we microscopically observed the infection processes of isolates of these four species on attached pearl plum leaves. For C. cigarro and C. siamense, the entire infection processes took 120 h; for C. fructicola and C. gloeosporioides, it only took 72 h. This is the first report of C. fructicola and C. cigarro causing anthracnose on pearl plum worldwide, and also the first report of C. siamense causing anthracnose on pearl plum in China.

Plum (Prunus salicina L.) is a traditional fruit in Southern China and is ubiquitous throughout the world. In August 2021, leaves of plum trees showed water-soaking spots and light yellow-green halos with incidence exceeding 50% in Babu district in Hezhou, Guangxi (N23°49′-24°48′, E111°12′-112°03′). To isolate the causal agent, three diseased leaves collected from three different trees growing in different orchards were cut into 5 mm × 5 mm pieces, disinfected with 75% ethanol for 10 sec, 2% sodium hypochlorite for 1 min and rinsed three times in sterile water. The diseased pieces were ground in sterile water and then kept static for about 10 min. Ten-fold serial dilutions in water were prepared and 100 µL of each dilution from 10-1 to 10-6 were plated on Luria-Bertani (LB) Agar. After incubation at 28℃ for 48 h, the proportion of isolates with similar morphology was 73%. Three representative isolates (GY11-1, GY12-1 and GY15-1) were selected for further study. The colonies were non-spore-forming, yellow, round, opaque, rod shaped, convex with smooth and bright neat edges. Biochemical test results showed that the colonies were strictly aerobic and gram-negative. The isolates were able to grow on LB agar containing 0-2% (w/v) NaCl and could utilize glucose, lactose, galactose, mannose, sucrose, maltose and rhamnose as a carbon source. They displayed a positive reaction for H2S production, oxidase, catalase and gelatin, but negative for starch. Genomic DNA of the three isolates was extracted for amplification of the 16S rDNA with primers 27F and 1492R. The resulting amplicons were sequenced. Additionally, five housekeeping genes atpD, dnaK, gap, recA, and rpoB of the three isolates were amplified using the corresponding primer pairs and sequenced. The sequences were deposited in GenBank (16S rDNA, OP861004-OP861006; atpD, OQ703328-OQ703330; dnaK, OQ703331-OQ703333; gap, OQ703334-OQ703336; recA, OQ703337-OQ703339; and rpoB, OQ703340-OQ703342). The isolates were identified as Sphingomonas spermidinifaciens based on the phylogenetic tree inferred by maximum-likelihood using MegaX 7.0 of the concatenated six sequences (multilocus sequence analysis, MLSA) compared with sequences from different Sphingomonas type strains . Pathogenicity of the isolates was tested on healthy leaves of the two-year-old plum plants in a greenhouse. The leaves were wounded by a sterilized needle and sprayed with bacterial suspensions prepared in PBS (Phosphate buffer saline) at OD600=0.5. PBS buffer solution was used as negative control. Each isolate was used to inoculate on 20 leaves per plum tree. The plants were covered with plastic bags to maintain high humidity. Dark brown-to-black lesions were observed on leaves 3 days post incubation at 28℃ with constant light. The average diameter of lesions was 1 cm after seven days, but the negative controls were symptomless. Bacteria reisolated from the diseased leaves were the same as the ones used for inoculation on the basis of morphological and molecular identification, fulfilling Koch's postulates. Plant disease caused by a Sphingomonas species has been reported on mango, pomeand Spanish melon. However, this is the first report of S. spermidinifaciens causing leaf spot disease of plum in China. This report will help to develop effective disease control strategies in the future.

Chilli (Capsicum annuum) is considered as one of the most important vegetables and spice crops throughout the world which is widely cultivated in China. In October 2019, fruit rot symptoms were observed on chilli in Guilin, Guangxi, China (N24°18′, E109°45′). Irregular dark green spots initially appeared on the middle or bottom of the fruit, then extended to larger grayish brown lesions and started to rot. In the late stage, the whole fruit dried up after water loss. Three disease samples were collected from three towns of different counties in Guilin where the disease incidence of chilli fruits was 15-30%. The margin of diseased fruits was cut into small pieces (3×3 mm), disinfected with 75% ethanol solution for 10 s, 2% NaOCl for 1 min, and rinsed in sterile distilled water three times. Tissue pieces were separately plated on potato dextrose agar (PDA) and incubated at 25°C for seven days. Fifty-four fungal isolates with similar morphology were consistently recovered from diseased tissues of three fruits, with 100% isolation frequency. Three representatives GC1-1, GC2-1 and PLX1-1 were selected for further analysis. The colonies produced abundant whitish to yellowish aerial mycelium on PDA after 7 days incubation at 25°C in the dark. Macroconidia cultured on carnation leaf agar (CLA) for 7 days were long, hyaline, falcate, with dorsal and ventral lines often gradually wider toward apex, curved apical cell and foot-shaped basal cell, mostly 2 to 5 septa, and ranged from 24.16 to 38.88 × 3.36 to 6.55 μm (average 31.39×4.48 μm), from 19.44 to 28.68 × 3.02 to 4.99 μm (average 23.02×3.89 μm), and from 20.96 to 35.05 × 3.30 to 6.06 μm (average 26.24×4.51 μm) for GC1-1, GC2-1, and PLX1-1, respectively. Microconidia were hyaline, fusoid or ovoid, one-septate or nonseptate, and ranged from 4.61 to 10.14 × 2.61 to 4.77 μm (average 8.13×3.58 μm), from 3.55 to 7.85 × 1.95 to 3.04 μm (average 5.79×2.39 μm), and from 6.75 to 18.48 × 3.05 to 9.07 μm (average 14.32×4.31 μm) for GC1-1, GC2-1, and PLX1-1, respectively. Genomic DNA was extracted from 7-day-old aerial mycelia of these isolates. The internal transcribed spacer (ITS), translation elongation factor (TEF1), calmodulin (CAM) and partial RNA polymerase second largest subunit (RPB2) were amplified using primers ITS4/ITS1, EF1/EF2, CL1/CL2A, and 5F2/7cR, respectively (White et al. 1990; O’Donnell et al. 2000, 2010). Sequences were deposited in GenBank (ITS: OQ080044-OQ080046; TEF1: OQ101589-OQ101591; CAM: OQ101586-OQ101588; RPB2: OQ101592-OQ101594). A maximum Likelihood (ML) phylogenetic tree was constructed with RAxML version 8.2.10 based on the concatenated sequences (ITS, CAM, TEF1, RPB2). According to morphology and phylogenetic analysis, the isolates were identified as Fusarium sulawesiense (Maryani et al. 2019). For pathogenicity tests, multiple punctures in a 5-mm-diameter circle were made with a sterilized toothpick on detached young healthy fruits, followed by inoculation with 10 μl of conidial suspension (106 spores/ml in 0.1% sterile Tween 20). Each isolate was inoculated onto eighteen fruits. Controls were inoculated with water containing 0.1% sterile Tween 20 under the same conditions. Symptoms were observed on the inoculated fruits 7 days after incubation at 25°C, whereas non-inoculated controls were asymptomatic. The fungus was re-isolated from inoculated chilli fruits, completing Koch’s postulates. To our knowledge, this is the first report of Fusarium sulawesiense causing fruit rot on Chilli in China. These results will provide valuable information for prevention and management of fruit rot on Chilli.

Xanthomonas oryzae pv. oryzae is the causal agent of bacterial blight, one of the most devastating diseases of rice. Here, a hypervirulent strain, C9-3, defeating Xa1, Xa10, xa13, and Xa23 resistance genes, was used to extract genomic DNA for single molecule real-time (SMRT) sequencing. After assembly, the genome consists of a single-circular chromosome with the size of 4,924,298 bp with G+C content of 63.7% and contains 4,715 genes. Annotation and analysis of the TALE genes using a suite of applications named AnnoTALE suggested that 17 transcription activator-like effectors, including 15 typical TALEs and 2 iTALEs/truncTALEs, were encoded in the genome. The approach and genome resource will contribute to the discovery of new virulence effectors and understanding on rice-X. oryzae pv. oryzae interactions.

Persimmon (Diospyros kaki Thunb.) is widely cultivated in China. On October 15, 2019, about 10% of persimmon fruits showed fruit rot in the orchards of Guilin, Guangxi, China (24°45′ N, 110°24′ E), which could cause more than 15% of yield losses. The initial symptoms of fruit rot exhibited irregular brown to black spots (range from 2 to 4 cm in diameter), the areas surrounding the blackened spots would be soft and rotten, and three diseased fruit samples were collected from three orchards, respectively. Tissues (5×5 mm) were cut from infected margins, surface-disinfected in 75% ethanol for 10 s, 2% NaClO for 2 min, rinsed three times in sterilized distilled water, and incubated on potato dextrose agar (PDA) at 25°C under 12/12 h light/darkness for a week. Forty-one tissues yielded morphologically similar cultures, and three representative isolates LPG1-1, LPG1-2, and YSG-1 were selected from three samples for further study, respectively. Their colonies showed wavy edges, white surfaces, and dense aerial hyphae on PDA after two weeks. Conidia were fusiform, straight to slightly curved, and 4-septate; basal cells were conical, hyaline, thin, and verruculose with two or three long and hyaline apical appendages and one short apical appendage; three median cells of LPG1-1 with length 14.06 to 17.69 μm (n=100), and LPG1-2 with length 14.03 to 17.61 μm (n=100) were dark brown to olivaceous, while three median cells of YSG-1 with length 12.54 to 15.58 μm (n=100) were dark brown. The conidial sizes of LPG1-1, LPG1-2, and YSG-1 were 17.41 to 27.68 × 4.63 to 8.55 μm (n=100), 18.06 to 27.41 × 4.33 to 8.21 μm (n=100), and 16.58 to 27.73 × 4.99 to 8.39 μm (n=100), respectively. The morphological characteristics were consistent with Neopestalotiopsis spp. (Maharachchikumbura et al. 2012; Maharachchikumbura et al. 2014). Primer pairs ITS4/ITS5, BT2a/BT2b, and EF1-526F/EF-1567R were used to amplify internal transcribed spacer (ITS), beta-tubulin (TUB2), and translation elongation factor 1 alpha (TEF1-α), respectively (Shu et al., 2020). All DNA fragments were sequenced by Sangon Biotech Co., Ltd. (Shanghai, China). Sequences have been deposited in GenBank (ITS: OM349120 to OM349122, TUB2: OM688188 to OM688190, TEF1-α: OM688191 to OM688193). Based on BLASTn analysis of ITS, TUB2, and TEF1-α sequences, the LPG1-1 and LPG1-2 showed over 99% similarity to N. saprophytica, and YSG-1 showed over 99% similarity to N. ellipsospora. Phylogenetic analysis of the three isolates was performed with MEGA10 (version 10.0) based on sequences of ITS, TUB2, and TEF1-α using maximum parsimony analysis. The results revealed that LPG1-1 and LPG1-2 were clustered with N. saprophytica, and YSG-1 was clustered with N. ellipsospora. Pathogenicity tests of three isolates were conducted on 72 healthy persimmon fruits with and without wounds, and 9 fruits are for each treatment. The wound was made by a sterilized needle. Fruits were pre-processed with 75% ethanol for 10 s, 1% NaClO for 2 min and rinsed three times in sterile water. Conidial suspensions (10 µL, 106 conidia/mL in 0.1% sterile Tween 20) were inoculated on each site (4 sites/fruit). Control group was treated with 0.1% sterile Tween 20. All inoculated sites were covered with wet cotton. The inoculated fruits were placed in a plastic box to maintain humidity at 28℃. After 5 days, all wounded fruits showed fruit rot, whereas unwounded and control fruits remained asymptomatic, there were significant differences (P

Jasmine (Jasminum sambac (L.) Aiton) is cultivated as a commercial floricultural crop in many countries around the world (Gao et al., 2020). From June to August 2020, leaf spots on jasmine were observed on a jasmine plantation in Hengzhou of Guangxi province. Over 40% of the plants in 6 ha fields were infected. This disease was prevalent in jasmine production area of China (Chen et al., 2012; Du et al., 2020). Symptoms began as chlorotic regions (from 5 to 10 mm in diameter) with light brown necrotic centers, which gradually expanded to the entire leaf. Eventually, the disease leaded to defoliation and dieback. The edges of the affected parts from diseased leaves were cut into pieces (3 mm2). Pieces were treated with 75% ethanol for 10 s, soaked in 2% NaClO solution for 1 min, washed three times with sterile water, and then incubated on potato dextrose agar (PDA) plates at 28℃ for 5 days in the dark. Fungal cultures that showed similar morphological characteristics were isolated, and three representative isolates (HL6-1 to HL6-3) were purified following Mo et al. (2018). The cultures on PDA changed from white to dark grey after 7 days and produced conidiomata after 14 days. Conidia were hyaline, one-celled, guttulate, cylindrical, of 12.07 to 18.09 × 4.04 to 8.05 μm, 13.17 to 16.35 × 4.22 to 6.13 μm and 10.11 to 22.17 × 3.65 to 8.1 μm for HL6-1, HL6-2 and HL6-3, respectively. Gray-brown or dark brown appressoria formed from conidia were subglobose or elliptical. Conidial appressoria and mycelial appressoria were 5.53 to 13.96 × 3.58 to 13.95 μm and 4.24 to 14.01 × 2.4 to 10.86 μm. Genomic DNA was extracted from three isolates and the partial internal transcribed spacer (ITS) regions, intergenic region of apn2 and MAT1-2-1 (ApMAT), and fragments of actin (ACT), glyceraldehydes-3-phosphate dehydrogenase (GAPDH), chitin synthase (CHS-1), and β-tubulin (TUB2) genes were amplified, sequenced and submitted to GenBank (ITS, ON115173 to ON115175; ApMat, ON156517 to ON156519; ACT, ON146469 to ON146471; GAPDH, ON156502 to ON156504; CHS-1, ON156507 to ON156509; TUB-2, ON156512 to ON156514). Phylogenetic tree was constructed with MrBayes v. 3.2.6 and MEGA v. 10.1.5 based on the concatenation of multiple sequences. Three isolates were grouped with strain C. siamense ICMP 18578. Results indicated three isolates were identified as Colletotrichum siamense Prihastuti, L. Cai & K.D. Hyde. To confirm the pathogenicity of the three isolates, four sets (five plants per set) of 160 healthy leaves of 2-year-old plants (J. sambac, eight leaves per plant) were slightly scratched with a sterilized toothpick at each of eight locations. Conidial suspension (1×106 conidia/mL) in 0.1% Tween 20 were inoculated onto each wounded spot of three sets as the treatment groups, while wounded leaves treated with sterile water as the control. All plants were covered with plastic bags and cultivated in phytotron (12 h/12 h light/dark, 28°C). After 7 days, irregular chlorotic regions with brown lesions were observed on inoculated leaves while no symptoms on controls. The same fungi were reisolated from inoculated leaves and confirmed by morphological and molecular identification, fulfilling Koch’s postulates. Colletotrichum siamense has been associated with leaf anthracnose of J. sambac in Vietnam (Wikee et al., 2011) and J. mesnyi in China (Zhang et al., 2019). To our knowledge, this is the first report of C. siamense causing jasmine anthracnose in China, which provides a reference for the management of this disease.

Mango (Mangifera indica L.) is one of the most important tropical fruits in China. Bacterial black spot is one of the primary factors limiting mango production and thus leads to huge economic losses (Bie et al. 2022). In June 2020, necrotic symptoms similar to bacterial black spot was observed with incidence 30% to 65% on mango cultivar Yuwen, Jinhuang, Tainong and Guifei in Baise, Guangxi, China. Typically, the lesions began as chlorotic spots that coalesced into an irregular shape, becoming black and slightly raised, with a yellow halo. Thirteen diseased samples collected from five orchards were cut into approximately 5-mm pieces, sterilized for 10 s with 75% ethanol, soaked with 2% NaClO for 1 min, and rinsed in sterilized water three times. The samples were then homogenized and a 10-fold serial dilution was made before plating onto Lysogeny broth (LB) agar. After incubation at 28°C for 3 days, one representative colony that was beige to yellow in color, round, convex and smooth with entire margins from each orchard was selected for further study. Genomic DNA was extracted to amplify the 16S rRNA gene (Lane et al. 1991). The resulting 16S rRNA sequences were compared in GenBank using BLASTn and shared at least 99% identity with Pantoea spp.. Furthermore, six housekeeping genes fusA, gyrB, leuS, pyrG, rplB and rpoB partial sequences of five isolates were amplified and sequenced (Delétoile et al. 2009). The sequences were deposited in GenBank (16S rRNA: OL413424 to OL413246, OP225727-OP225728; leuS: OL441796, OL441798 to OL441801; fusA, gyrB, leuS, pyrG, rplB and rpoB: OP272638-OP272662). The five bacterial isolates were classified as P. vagans based on the phylogenetic tree of the concatenated sequences and sequences derived from different Pantoea reference isolates inferred by maximum-likelihood using MegaX software (Kumar et al. 2018). Biochemical tests showed the isolates were Gram-negative, oxidase negative, and hydrogen oxidase positive, and could use D-glucose, D-fructose, L-rhamnose, D-galactose and D-mannitose as a carbon resource (Bradbury, 1986). Pathogenicity tests were performed on mango cv. Yuwen. The representative isolate was inoculated by infiltration with sterile needleless syringes on healthy leaves and spraying onto slightly scratched leaves with bacterial suspensions (OD600=0.1) respectively (Kutschera, et al. 2019). A Xanthomonas citri pv. mangiferaeindicae (Xcm) suspension and sterilized water were used as positive and negative controls, respectively. Inoculated plants were kept with 90 ± 5% relative humidity and 28 ± 1°C in the greenhouse for 1 week. Black to brown necrotic symptoms were observed on all leaves inoculated by infiltration except the negative control. These were observed in plants inoculated by spraying only after 2 weeks. Bacteria re-isolated from diseased tissues were consistent with the inoculated isolates and identified as P. vagans, fulfilling Koch’s postulates. To date, P. vagans have been isolated from eucalyptus with bacterial blight and dieback, and maize with brown stalk rot (Brady et al. 2009). However, to our knowledge, this is the first report of P. vagans causing bacterial necrosis on mango in China. It was also found that some of the diseased samples were coinfected with P. vagans and Xcm in our investigation. Therefore, it is necessary to further study the infection mechanisms of this pathogen.

Persimmon originated from China where it has a long cultivation history. Anthracnose fruit rot and leaf blight caused by Colletotrichum species are major diseases of persimmon in China and cause severe economic losses. To determine the species causing anthracnose of persimmon in Guilin, Guangxi province, diseased samples were collected from the four local counties: Gongcheng, Yangshuo, Pingle, and Lipu. Seventy-five isolates were obtained from persimmon samples with anthracnose symptoms and had similar morphological characteristics. Isolates were identified using a BLAST search and phylogenetic analysis of the internal transcribed spacer region, glyceraldehyde -3-phosphate dehydrogenase, partial actin, β-tubulin, chitin synthase genomic regions, Apn2-Mat1-2 intergenic spacer partial mating type gene and calmodulin genes. Five species: C. fructicola, C. horii, C. karsti, C. cliviicola and C. siamense, accounted for 54.7%, 25.3%, 12.0%, 5.3% and 2.7%, respectively, of the total isolates. All five Colletotrichum species were pathogenic on attached leaves and detached fruits of persimmon (cv. Gongcheng Yueshi) in pathogenicity assays. The infection processes of the five Colletotrichum species were observed on persimmon leaves using light microscopy. Conidia of C. fructicola germinated at 12 hours post inoculation (hpi), while quickly formed acervuli at 6 days post inoculation (dpi) and showed the most aggressive. By contrast, conidia of C. cliviicola germinated at 3 hpi, but produced the acervuli at 8 dpi, and showed the least aggressive. This is the first description of C. fructicola, C. cliviicola and C. siamense as causal agents of persimmon anthracnose in Guangxi province, China.

To practice green development in highway construction and improve the theory slope ecological restoration, this paper analyzes the connotation characteristics and idea of green highway, and puts forward the needs and management suggestions of green highway idea for slope ecological restoration. The results show that: (1) the ecological restoration of highway slope should adapt to the needs of green highway development in the new period from five aspects: optimizing design, intensive using of resources, adopting different repair techniques, considering the life cycle costs and building beautiful highways. (2) The high-quality development of ecological restoration of highway slopes can promote from four types of initiatives: encouragement, compulsiveness, recommendation and guidance. The research results provide guidance and strategy for develops slope ecological restoration, which is conducive to promoting the transportation industry to practice green development and ecological civilization strategy.

There is nearly 5,800 ha of Sanhua plum (

Mango is an economically important fruit crop in southern China. However, leaf spots restrict the development of mango trees, reducing the yield and production. Pestalotioid fungi are one of the major agents causing leaf spots on mango. During 2016 and 2017, 21 isolates of pestalotioid fungi associated with leaf spots on mango leaves were collected from five provinces in southern China: Guangxi, Hainan, Yunnan, Guangdong, and Fujian. All 21 isolates were subjected to morphological characterization and DNA sequence analysis. The morphological data were combined with analyses of concatenated sequences of the ITS (internal transcribed spacer), TEF 1-α (translation elongation factor), and TUB2 (β-tubulin) for higher resolution of the species identity of these isolates. The results showed that these isolates belong to Neopestalotiopsis clavispora, Pestalotiopsis adusta, P. anacardiacearum, P. asiatica, P. photinicola, P. saprophyta, P. trachicarpicola, and Pseudopestalotiopsis ampullacea. Pathogenicity test results showed that all these species could cause symptoms. On detached mango leaves (cv. Tainong), early foliar symptoms on leaves were small yellow-to-brown lesions. Later, these spots expanded with uneven borders, turned white to gray, and coalesced to form larger gray patches. To our knowledge, this is the first description of N. clavispora, P. adusta, P. asiatica, P. photinicola, P. saprophyta, P. trachicarpicola, or Ps. ampullacea as causal agents for leaf spots on mango worldwide.

Plum (

Cavendish banana (Musa spp. AAA group) is an important tropical and subtropical fruit with significant economic value. It is widely planted in Guangxi, Yunnan, Hainan, Fujian and Guangdong provinces in China. In November 2020, leaf spots were observed on nearly 80% of the plants growing in three Cavendish banana plantations in Chongzuo, Guangxi, China. The symptoms on Cavendish banana leaves initially appeared as small black necrosis spots, which gradually expanded and connected, eventually covered the entire leaf. Three diseased leaves from three plantations were collected, sectioned into small pieces (5 ×5 mm), surface sterilized (10 s in 75% ethanol, followed by 1 min in 1% sodium hypochlorite and rinsed three times in sterile water) and placed on potato dextrose agar (PDA) at 28℃ for 5 days for pathogen isolation. The fungal colonies were white, cottony, while the reverse sides were white, concentric circles with yellowish-brown discoloration in 7-day cultures. The conidia were hyaline, aseptate, cylindrical, oval, measuring 10.3 to 17.71 μm (mean 14.06 ± 1.45 μm; n = 200) in length and 4.48 to 9.57 μm (mean 7.46 ± 0.69 μm; n = 200) in width. Three representative isolates (DX1-5, LZ4-5, and FS1-3) were obtained by monosporic isolation. The partial internal transcribed spacer (ITS) regions, actin (ACT), chitin synthase (CHS-1), glyceraldehydes-3-phosphate dehydrogenase (GAPDH), calmodulin (CAL), and β-tubulin (TUB2) were amplified from genomic DNA for the three isolates (Weir et al. 2012). The sequences of the amplified fragments were deposited in GenBank (accessions OL361844 to OL361858, for GAPDH, CAL, ACT, CHS-1, and TUB2 of isolate DX1-5, LZ4-5 and FS1-3; OL305066 to OL305068 for ITS) and showed over 99% identities with the corresponding sequences of C. citricola. A neighbor-joining phylogenetic tree based on the above six genes of type or ex-type specimens of Colletotrichum (Fu et al. 2019) was constructed with MEGA 5.2 using the concatenation of multiple sequences (Kumar et al. 2016). All three isolates clustered together with the type culture of C. citricola (CBS 134228, CBS 134229, CBS 134230) with 82% bootstrap support in the phylogenetic tree. According to the molecular and morphological characteristics, all three isolates were identified as C. citricola. Pathogenicity tests were conducted on one-month-old primary hardened tissue culture plantlets. Tender, healthy leaves were gently scratched with a sterile needle, and each wound site was inoculated with sterile cotton impregnated with conidial suspension (106 spores/ml) for each isolate. Wounded leaves were treated with sterile cotton impregnated with conidial suspension of C. fructicola as positive controls and sterile water as negative controls. Each isolate was inoculated with three tissue culture plantlets, six inoculated sites on each plantlet, the same as controls. All inoculated tissue culture plantlets were covered with plastic bags to maintain high humidity and placed in a 28℃ growth chamber with constant light. Black necrotic lesions were clearly observed on the inoculated leaves and the positive controls after 7 days, whereas no symptoms appeared on the negative control leaves. The fungus was re-isolated from inoculated leaves, and these isolates matched the morphological and molecular characteristics of the original isolates confirming Koch's postulates. To our knowledge, this is the first report of leaf spot caused by C. citricola on Cavendish banana worldwide.

Among two-dimensional materials, Fe3GeTe2 has come to occupy a very important place owing to its ferromagnetic nature with one of the highest Curie temperatures among known van der Waals materials and the potential for hosting skyrmions. In this combined experimental and theoretical work, we investigate the magnetic bubble domains as well as the microscopic domain wall profile using spin-polarized scanning tunneling microscopy in combination with atomistic spin-dynamics simulations performed with parameters from density functional theory calculations. We find a weak magneto-electric effect influencing the domain wall width by the electric field in the tunneling junction and determine the critical magnetic field for the collapse of the bubble domains. Our findings shed light on the origins of complex magnetism that Fe3GeTe2 exhibits.

We present an unexpectedly strong influence of the proximity effect between the bulk Ru(0001) superconductor and atomically thin layers of Co on the crystal structure of the latter. The Co monolayer grows in two different modifications, such as hcp stacking and a reconstructed ε-like phase. While hcp islands show a weak proximity effect on Co and a little suppression of superconductivity in the substrate next to it, the more complex ε-like stacking becomes almost fully superconducting. We explain the weak proximity effect between Ru and hcp Co and the rather abrupt jump of the superconducting order parameter by a low transparency of the interface. In contrast, the strong proximity effect without a jump of the order parameter in the ε-like phase indicates a highly transparent interface. This work highlights that the proximity effect between a superconductor and a normal metal strongly depends on the crystal structure of the interface, which allows to engineer the proximity effect in hybrid structures.

Ultra-high molecular weight polyethylene (UHMWPE) is a kind of high performance polymer. But sintering-Molded UHMWPE thick products have the problems of long processing time and structural heterogeneity in products. Here, we compared the time required to complete sintering of UHMWPE thick products with different molecular weights, and found that the higher the molecular weight, the longer the time it took to complete sintering. With the increase of sintering time, the homogeneity of UHMWPE thick products can be improved continuously and will reach a saturation state, at which increasing the sintering time will not change various properties of the products. We compared several kinds of properties of UHMWPE thick products with different molecular weights and found that with the increase of molecular weight, the hardness, Young's modulus, tensile strength, and yield strength of the products barely change, but the elongation at break and the impact strength decrease. Finally, we attribute this phenomenon to the thickness increase of amorphous region.

Coal combustion has represented a very important atmospheric mercury (Hg) source in the past 5 decades, especially in eastern Asia. Compared with coal-fired power plants (CFPPs) and industrial boil...

Litchi (Litchi chinensis Sonn.), a native fruit tree from southern China, has been planted in many subtropical and tropical countries for its fruit which are considered delicious and of medicinal value (Anderson et al. 2013). Anthracnose, one of the most important diseases on litchi, can cause flower drop, fruit drop, and fruit rot. Infected leaves form dark brown spots which turn to reddish brown with gray-white edges. Infected fruits formed dark brown spots which developed eventually to entire black rotted fruits. On both tissues, small dots of acervuli appeared with high humidity (Lai et al. 2004). On 20 April 2019, two leaf spots samples of litchi from different plants were collected from a 2 ha litchi orchard in Xintang Town (N 22.38˚, E 108.61˚), Qinzhou City, Guangxi province. The incidence of leaf spots in the orchard was above 20%. Each sample was cut into multiple pieces targeting zone between symptomatic and healthy plant tissues, disinfected with 75% ethanol for 10 s and 1% sodium hypochlorite (NaClO) for 1 min, and then washed three times with sterilized distilled water. The sterilized leaf tissues were placed on potato dextrose agar (PDA) and incubated at 28°C in darkness for one week. The growing hyphae from each sample was transferred to fresh PDA. The pieces from each leaf yielded a similar fungal morphotype over 75% of the time, and a representative one from each leaf was retained and called LZ1-1 and LZ3-1. The resulting colonies were incubated on the PDA for 7 days with gray to white aerial tufted hyphae, and abundant colorless to pale orange conidia in center of colony. The conidia were smooth, apex obtuse, base truncate, straight, cylindrical, and the contents remained granular. The conidial size of LZ1-1 was 10.6 to 21.4 × 4.5 to 9.1 μm (n=100) and that of LZ3-1 was 12.7 to 16.7 × 5.5 to 8.0 μm (n=100). Appressoria of LZ1-1 (6.9 to 14.9 × 6.0 to 11.1 μm) (n=100) and LZ3-1 (6.5 to 15.4 × 5.4 to 11.4 μm) (n=100) were pale to medium brown, ovoid to bullet-shaped, not nodose, and smooth-walled to undulate. DNA was extracted from two isolates, followed by PCR amplification and sequencing using primers for the rDNA internal transcribed spacer (ITS), actin (ACT), calmodulin (CAL), chitin synthase (CHS-1), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), and β-tubulin (TUB2) (Damm et al. 2012). The resulting sequences were deposited in GenBank (ITS: MW494453 and MW494454, ACT: MW495034 and MW495035, CAL: MW495036 and MW495037, CHS-1: MW495038 and MW495039, GAPDH: MW495040 and MW495041, TUB2: MW495042 and MW495043). The concatenated sequences comprised of six genomic regions of LZ1-1, LZ3-1 and other sequences of Colletotrichum obtained from GenBank were used to construct a Neighbor-Joining (NJ) tree with 1000 bootstrap replicates using MEGA4 (Tamura et al. 2007). The results revealed both LZ1-1 and LZ3-1 were clustered with type strain of C. karstii with high bootstrap value. The pathogenicity of the two isolates was determined by inoculating on leaves of 1-year-old litchi saplings in the greenhouse. Slight scratches were made on the surface of healthy leaves and 10 μL of spore suspension (106 conidia/mL) in 0.1% Tween 20 were inoculated onto each wounded spot. The blank control groups were inoculated with 10 μL 0.1% Tween 20. Each isolate was inoculated onto at least 27 leaves of three saplings, with each leaf wounded at spots. The inoculated saplings were placed in a greenhouse (12 h/12 h light/dark, 25 ± 2°C), and humidity maintained by covering plastic bags. The leaves inoculated with spore suspension showed reddish-brown spots after one week, while no symptoms were observed in the control. Each fungal isolate was consistently reisolated from inoculated leaves, thus fulfilling Koch's postulates. It was reported that members of the C. acutatum species complex and the C. gloeosporioides species complex could cause anthracnose on litchi (Ling et al. 2019), including C. gloeosporioides, C. siamense, C. fioriniae, and C. simmondsii (Ling et al. 2019; 2020). To our knowledge, this is the first report of anthracnose on litchi in China caused by C. karstii, a member of the C. boninense species complex. This study expands the understanding of the pathogen of anthracnose on litchi which can lead to improved management and control.

A previous study using healthy “Valencia” orange fruit found that juicing extraction methods dramatically changed the orange juice (OJ) flavor and phytochemical profiles. The present study was conducted to confirm whether the same changes occur when Huanglongbing (HLB)-affected oranges were used. HLB has extensively spread to most OJ processing regions around the world, substantially deteriorating fruit and juice flavor quality and altering the phytochemical profiles. In this study, the effect of two major juice extractor types, a shear force extractor (SFE) and a reamer extractor (RE), on the juice quality and physiochemical profile was assessed using HLB-affected orange fruit. Juice extracted via SFE resulted in a lower yield with lower peel oil and higher pellet (peel tissue particles) content compared to juice obtained via RE. The SFE juice also had higher levels of hesperidin and other flavonoid glycosides, mainly due to plentiful peel tissue particles. The SFE juice was also abundant in carotenoids due to a large amount of flavedo particles in the juice. On the other hand, polymethoxylated flavones occurred at higher concentrations in the RE juice, and this may be due to the higher peel oil content in this juice. The SFE juice was rich in flavonoid glycosides and carotenoids, which are associated with potential antioxidant properties, however, the extra portion of the phytonutrients mostly existed in the pellets and possibly had low bioavailability. The results obtained from the HLB-affected oranges are in agreement with the previous observations of healthy oranges.

Papaya (Carica papaya L.) is a rosaceous plant widely grown in China, which is economically important. Anthracnose caused by Colletotrichum sp. is an important postharvest disease, which severely affects the quality of papaya fruits (Liu et al., 2019). During April 2020, some mature papaya fruits with typical anthracnose symptoms were observed in Fusui, Nanning, Guangxi, China with an average of 30% disease incidence (DI) and over 60% DI in some orchards. Initial symptoms of these papayas appeared as watery lesions, which turned dark brown, sunken, with a conidial mass appearing on the lesions under humid and warm conditions. The disease severity varied among fruits, with some showing tiny light brown spots, and some ripe fruits presenting brownish, rounded, necrotic and depressed lesions over part of their surface. Samples from two papaya plantations (107.54°E, 22.38°N) were collected, and brought to the laboratory. Symptomatic diseased tissues were cut into 5 × 5 mm pieces, surface sterilized with 2% (v/v) sodium hypochlorite for 1 minute, and rinsed three times with sterilized water. The pieces were then placed on potato dextrose agar (PDA). After incubation at 25°C in the dark for one week, colonies with uniform morphology were obtained. The aerial mycelium on PDA was white on top side, and concentric rings of salmon acervuli on the underside. A gelatinous layer of spores was observed on part of PDA plates after 7 days at 28°C. The conidia were elliptical, aseptate and hyaline (Zhang et al., 2020). The length and width of 60 conidia were measured for each of the two representative isolates, MG2-1 and MG3-1, and these averaged 13.10 × 5.11 μm and 14.45 × 5.95 μm. DNA was extracted from mycelia of these two isolates with the DNA secure Plant Kit (TIANGEN, Biotech, China). The internal transcribed spacer (ITS), partial actin (ACT), calmodulin (CAL), chitin synthase (CHS), β-tubulin 2 (TUB2) and glyceraldehyde 3-phosphate dehydrogenase (GAPDH) regions were amplified by PCR and sequenced. The sequences were deposited into GenBank with accessions MT904003, MT904004, and MT898650 to MT898659. BLASTN analyses against the GenBank database showed that they all had over 99% identity to the type strain of Colletotrichum siamense isolate ICMP 18642 (GenBank accession numbers JX010278, GQ856775, JX009709, GQ856730, JX010410, JX010019) (Weir et al., 2012). A phylogenetic tree based on the combined ITS, ACT, CAL, CHS, TUB2 and GAPDH sequences using the Neighbor-joining algorithm also showed that the isolates were C. siamense. Pathogenicity tests were conducted on 24 mature, healthy and surface-sterilized papaya fruits. On 12 papaya fruits, three well separated wounded sites were made for inoculation, and for each wounded site, six adjacent pinhole wounds were made in a 5-mm-diameter circular area using a sterilized needle. A 10 µl aliquot of 1 × 106 conidia/ml suspension of each of the isolates (MG2-1 and MG3-1) was inoculated into each wound. For each isolate, there were six replicate fruits. The control fruits were inoculated with sterile distilled water. The same inoculation was applied to 12 non-wound papaya fruits. Fruits were then placed in boxes which were first washed with 75% alcohol and lined with autoclaved filter paper moistened with sterilized distilled water to maintain high humidity. The boxes were then sealed and incubated at 28°C. After 10 days, all the inoculated fruits showed symptoms, while the fruits that were mock inoculated were without symptoms. Koch's postulates were fulfilled by re-isolation of C. siamense from diseased fruits. To our knowledge, this is the first report of C. siamense causing anthracnose of papaya in China. This finding will enable better control of anthracnose disease caused by C. siamense on papaya.

Alocasia macrorrhiza (L.) Schott, known as Alocasia is found in the Araceae, and is widely planted in southern China for its ornamental and medicinal value. This plant has a wide range of pharmacological effects, and has potential anti-tumor activity (Lei et al. 2013). In July of 2019, leaf spots were observed on A. macrorrhiza in the Xixiangtang Area, Nanning, Guangxi, China. Disease symptoms began with water-soaked yellow-green spots and progressed to form brown, round or oval lesions with yellow halos. Under severe conditions, spots merged into larger irregular lesions. More than 60% of the plants in a 0.5 ha field showed disease symptoms. Symptomatic leaves were collected and cut into small pieces (3×3 mm). Leaf pieces from the margin of the necrotic tissue were surface sterilized in 75% alcohol for 10 s, followed by 2% sodium hypochlorite solution for 2 min, then rinsed three times in sterile distilled water. Tissues were plated on potato dextrose agar (PDA) and incubated at 28°C for 5 days in the dark. Among over 30 isolates, most shared a similar morphology, the isolation rate of these was 86.7% and three of these (GY1-1A, GY1-1B, and GY1-1C) were chosen for single-spore purification and used for fungal morphological characterization and identification. White feathery aerial mycelia with olivaceous gray mycelia below were observed in 7-day cultures. After 14 days, orange conidia were observed. Conidia were hyaline, guttulate, smooth, one-celled, and cylindrical, averaged 13.79 μm × 5.26 μm, 13.89 μm × 5.33 μm and 13.92 μm × 5.42 μm for GY1-1A, GY1-1B and GY1-1C, respectively. Appressoria were mostly irregular in outline, deeply lobed or lightly lobed, gray brown to dark brown, conidial appressoria were 7.93 to 8.74 μm × 5.26 to 5.42 μm, mycelial appressoria were 7.15 to 10.11 μm × 5.60 to 7.44 μm. These morphological characteristics were similar to the C. siamense as previously described (Weir et al. 2012). The partial internal transcribed spacer (ITS) regions, actin (ACT), chitin synthase (CHS-1), glyceraldehydes-3-phosphate dehydrogenase (GAPDH), calmodulin (CAL), β-tubulin (TUB2), and the intergenic region of apn2 and MAT1-2-1 (ApMAT) were amplified from genomic DNA for the three isolates using primers ITS4/ITS1 (White et al. 1990), ACT-512F/ACT-783R, CHS-79F/CHS-354R, GDF1/GDR1, CL1C/CL2C, Bt2a/Bt2b (Weir et al. 2012), and AM-F/AM-R (Silva et al. 2012) and sequenced. All sequences showed over 99% identity with C. siamense and were deposited in GenBank (ITS, MW040179-MW040181; ACT, MW049220-MW049222; CHS-1, MW049229-MW049231; GAPDH, MW049232-MW049234; CAL, MW049226-MW049228; TUB, MW049235-MW049237; ApMAT, MW049223-MW049225). Maximum Likelihood (ML) phylogenetic tree was constructed with MEGA 5 using the concatenation of multiple sequences (ACT, CHS-1, GAPDH, ITS, TUB2, CAL). According to the phylogenetic tree, all three isolates were found with C. siamense with 95% bootstrap support. To confirm pathogenicity, three sets (three plants per set) of healthy leaves were slightly scratched with autoclaved toothpicks at each of eight locations. Each inoculation location was a cross (2 mm length) and inoculation location was at least 3 cm apart. Ten μl of conidial suspension (106 conidia /ml in 0.1% sterile Tween 20) was applied to the inoculation areas. A control group was mock inoculated with 0.1% sterile Tween 20. Plants were covered with plastic bags to maintain a high humidity environment and placed in a 28°C growth chamber with constant light for 7 days. Inoculated leaves showed yellowish brown spots (0.4 × 0.65 cm), but no symptoms were observed in the control group. The fungus was reisolated from inoculated leaves, and these isolates matched the molecular and morphological characteristics of the original isolates confirming Koch's postulates. Reported hosts of this pathogen include Coffea arabica, Carica papaya, Melilotus indicus and Litchi chinensis (Weir et al. 2012; Qin et al. 2017; Ling et al. 2019) and so on. To our knowledge, this is the first report of C. siamense causing leaf spot on A. macrorrhiza in China. The identification of this pathogen provides a foundation for the management of leaf spot on this medicinal plant.

Mango is one of the important commercially cultivated fruit crops in southern China. In continuing research on foliar diseases of mango in south of China during 2016-2017, leaf spot disease was common at all mango orchards investigated. The purpose of this study was to investigate Fusarium species associated with leaf spots of mango in the main production areas of China, and to identify them to species. Twenty-two Fusarium isolates were obtained from diseased leaves from seven provinces (Fujian, Guangdong, Guangxi, Guizhou, Hainan, Sichuan and Yunnan), and then identified using morphological characteristics and phylogenetic analysis. These isolates were from seven species: F. concentricum, F. hainanense, F. mangiferae, F. pernambucanum, F. proliferatum, F. sulawesiense, and F. verticillioides. We found all 22 isolates to be capable of causing leaf spot symptoms on artificially wounded leaves. To our knowledge, this is the first report of F. concentricum, F. hainanense, F. mangiferae, F. pernambucanum, F. sulawesiense and F. verticillioides associated with leaf spots on mango in China, and the first for F. concentricum, F. hainanense, F. pernambucanum, F. sulawesiense from mango worldwide. This is one of the few reports on Fusarium species as potential causal agents of mango leaf spots.

Lotus seed is well known as traditional food and medicine, but its skin is usually discarded. Recent studies have shown that lotus seed skin contains a high concentration of proanthocyanidins that have multi-functions, such as antioxidation, anti-inflammation, and anti-cancer effects. In the present study, we aimed to isolate and purify the proanthocyanidins from lotus seed skin by acetone extraction and rotary evaporation, identify their chemical structures by HPLC-MS-MS and NMR, and further investigate the antioxidant properties of the extract purified by macroporous resin (PMR) from lotus seed skin both in vitro and in vivo. The results showed that PMR mainly contained oligomeric proanthocyanidins, especially dimeric procyanidin B1 (PB1), procyanidin B2 and procyanidin B4. Although it had limited ability to directly scavenge radicals in vitro, PMR could significantly enhance the expressions of antioxidant proteins via activation of nuclear factor-E2-related factor 2 (Nrf2)-antioxidant response element (ARE) pathway in HepG2 cells. Molecular data revealed that PB1, a major component in PMR, stabilized Nrf2 by inhibiting the ubiquitination of Nrf2, which led to subsequent activation of the Nrf2-ARE pathway, including the enhancements of Nrf2 nuclear translocation, Nrf2-ARE binding and ARE transcriptional activity. Moreover, the in vivo results in high fat diet-induced mice further verified the powerful antioxidant property of PMR. These results revealed that lotus seed skin is a promising resource for functional food development.

Zizyphus mauritiana Lam. is an important tropical fruit tree and has significant economic value. It is widely planted in Hainan, Guangdong, Guangxi and Fujian provinces in China (Yang et al. 2017). In March 2019, leaf spot was observed on leaves of Z. mauritiana at Bagui fields in Nanning, Guangxi, China, with incidence exceeding 50%. Symptomatic leaves developed a yellow to tan-brown sunken lesion and finally abscised. To isolate the pathogen causing the symptoms, small pieces (5 × 5 mm) of infected leaves were surface sterilized by exposure to 75% ethanol for 10 sec, 1% sodium hypochlorite for 1 min and rinsed three times in sterile water. Fifty pieces were isolated, surface sterilized, and pieces were plated onto potato dextrose agar (PDA) and grown at 28°C for 7 days. The isolation rate of Colletotrichum species was 100%. Three representative isolates (DQZ3-1, DQZ3-2 and DQZ3-3) were selected for further study. Mycelia were greyish-white for all three isolates, with isolate DQZ3-1 also appearing dark green in the center of the colony. Conidia were elliptical, aseptate and hyaline, with sizes of 13.4 ± 0.12 µm × 5.7 ± 0.1 µm, 14.8 ± 0.1 µm × 5.8 ± 0.1 µm and 15.1 ± 0.1 µm × 5.5 ± 0.1 µm for DQZ3-1, DQZ3-2 and DQZ3-3, respectively. Genomic DNA was extracted using the DNAsecure Plant Kit [Tiangen Biotech (Beijing) Co., Ltd] and the internal transcribed spacer (ITS), partial actin (ACT), calmodulin (CAL), chitin synthase (CHS-1), beta-tubulin (TUB2), and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) genes were sequenced (Weir et al. 2012). Phylogenetic analysis of the three isolates was performed with MEGA-X (Version 10.0) based on sequences of multiple loci (ITS, ACT, CAL, CHS-1, TUB2 and GAPDH) using Maximum Likelihood analysis. Isolate DQZ3-1 was identified as C. fructicola, and the other two isolates, DQZ3-2 and DQZ3-3, were identified as C. siamense (accessions MT039396 to MT039410, for ACT, CAL, CHS-1, GAPDH and TUB2 of DQZ3-1, DQZ3-2 and DQZ3-3; MT041651 to MT041653 for ITS of DQZ3-1, DQZ3-2 and DQZ3-3). Pathogenicity tests were conducted on 1-year-old plants. Young, healthy leaves were artificially wounded by gently scratching with a sterile needle and 10 µl droplets of conidial suspension (106 spores/ml) applied per wound site for each isolate. Some wounded leaves were inoculated with 10 µl droplets of water as controls. Each isolate was inoculated onto three plants, with 15 leaves at least for each plant, same as controls. All inoculated plants were sprayed with water and covered with plastic bags to maintain high humidity. Symptomatic lesions were observed on the inoculated leaves after 7 days at 28°C, whereas no symptoms were observed on the control leaves. To fulfill Koch's postulates, fungi were re-isolated from 50 symptomatic leaf pieces and fungi re-isolated from each leaf piece were morphologically identical to the inoculated isolates, for a 100% isolation frequency. To our knowledge, this is the first report of leaf spot caused by C. fructicola and C. siamense on Z. mauritiana worldwide. This research may accelerate the development of future epidemiological studies and management strategies for anthracnose caused by C. fructicola and C. siamense on Z. mauritiana.

Colletotrichum gloeosporioides, one of the main agents of mango anthracnose, causes latent infections in unripe mango, and leads to huge economic losses during storage and transport. Dimethyl trisulfide (DMTS), one of the main volatile compounds produced by some microorganisms or plants, has shown antifungal activity against some phytopathogens in previous studies, but its effects on C. gloeosporioides and mechanisms of action have not been well characterized. In fumigation trials of conidia and mycelia of C. gloeosporioides for 2, 4, 6, 8, or 10 h, at a concentration of 100 μL/L of air space in vitro, DMTS caused serious damage to the integrity of plasma membranes, which significantly reduced the survival rate of spores, and resulted in abnormal hyphal morphology. Moreover, DMTS caused deterioration of subcellular structures of conidia and mycelia, such as cell walls, plasma membranes, Golgi bodies, and mitochondria, and contributed to leakage of protoplasm, thus promoting vacuole formation. In addition, to better understand the molecular mechanisms of the antifungal activity, the global gene expression profiles of isolate C. gloeosporioides TD3 treated in vitro with DMTS at a concentration of 100 μL/L of air for 0 h (Control), 1 h, or 3 h were investigated by RNA sequencing (RNA-seq), and over 62 Gb clean reads were generated from nine samples. Similar expressional patterns for nine differentially expressed genes (DEGs) in both RNA-seq and qRT-PCR assays showed the reliability of the RNA-seq data. In comparison to the non-treated control groups, we found DMTS suppressed expression of β-1, 3-D-glucan, chitin, sterol biosynthesis-related genes, and membrane protein-related genes. These genes related to the formation of fungal cell walls and plasma membranes might be associated with the toxicity of DMTS against C. gloeosporioides. This is the first study demonstrating antifungal activity of DMTS against C. gloeosporioides on mango by direct damage of conidia and hyphae, thus providing a novel tool for postharvest control of mango anthracnose.

Mango (Mangifera indica L.) is an economically significant fruit crop in provinces of southern China including Hainan, Yunnan, Sichuan, Guizhou, Guangdong and Fujian. The objective of this study was to examine the diversity of Colletotrichum species infecting mango cultivars in major growing areas in China, using morphological and molecular techniques together with pathogenicity tests on detached leaves and fruits. Over 200 Colletotrichum isolates were obtained across all mango orchards investigated, and 128 of them were selected for sequencing and analyses of actin (ACT), chitin synthase (CHS-1), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), the internal transcribed spacer (ITS) region, β-tubulin (TUB2) genomic regions. Our results showed that the most common fungal isolates associated with mango in southern China involved 13 species: Colletotrichum asianum, C. cliviicola, C. cordylinicola, C. endophytica, C. fructicola, C. gigasporum, C. gloeosporioides, C. karstii, C. liaoningense, C. musae, C. scovillei, C. siamense and C. tropicale. The dominant species were C. asianum and C. siamense each accounting for 30%, and C. fructicola for 25%. Only C. asianum, C. fructicola, C. scovillei and C. siamense have previously been reported on mango, while the other nine Colletotrichum species listed above were first reports associated with mango in China. From this study, five Colletotrichum species, namely C. cordylinicola, C. endophytica, C. gigasporum, C. liaoningense and C. musae were the first report on mango worldwide. Pathogenicity tests revealed that all 13 species caused symptoms on artificially wounded mango fruit and leaves (cv. Tainong). There was no obvious relationship between aggressiveness and the geographic origin of the isolates. These findings will help in mango disease management and future disease resistance breeding.

Mango (Mangifera indica L.) is an economically important fruit in southern provinces of China. In May 2012, field surveys including 2,250 mango trees were done in nine orchards of five different counties in Guangxi Province. An outbreak of gummosis was observed in the province involving over 30,000 ha with an average of 50% disease incidence (DI) and a maximum of 70% in some orchards. Until then, gummosis had been considered a common but not serious disease. In 2012, high temperatures in April and extensive rain in May favored increased disease development. Infected plants showed abundant gum secretion from branches, stems, and main trunks. Some branches died from the disease. During the early stages of infection, branches or stems turned brown followed by xylem necrosis and exudation of a milky sap. The sap turned yellow and finally formed amber gum within several days. Initially, the gum appeared as small droplets, increasing in number, and covering most of the branches and the trunk with bark cracking under severe conditions. On potato dextrose agar (PDA), isolates with similar morphology were consistently recovered from symptomatic plant tissues after surface sterilization in 75% ethanol for 30 seconds and then in 0.1% mercuric chloride for 1 min. Five single-spore isolates from five different locations in Guangxi Province were used to evaluate characteristics of the pathogen. On PDA, cultures were gray with an irregularly distributed, fast-growing, and fluffy aerial mycelium, showing a dark underside as the colony changed from greenish to black after 5 days at 28°C. After 1 month, cultures produced globose pycnidia. Conidia were elliptical and hyaline when immature, becoming dark brown and one-septate, longitudinally striate when mature, and ranged from 20.0 to 28.0 × 10.5 to 16.0 μm (average 23.3 × 13.7 μm). Paraphyses produced within the tissues of pycnidia were hyaline, cylindrical, nonseptate, and up to 61 μm long. The fungus was identified as Lasiodiplodia theobromae (Pat.) Griffon & Maubl. (=Botryosphaeria rhodina (Cooke) Arx) based on morphological and cultural characteristics (1,2). The rDNA internal transcribed spacer region of one isolate showed 100% identity to L. theobromae (GenBank HM346876.2) and was deposited in GenBank (JX982240). Pathogenicity of the five isolates was tested in the field on healthy tissues in June 2012. Five green twigs and five 3-year-old branches were used. Three wounds were made on each twig or branch with a sterilized needle. Mycelial plugs were placed on wounds and covered with Parafilm. Uncolonized PDA plugs were used as controls. Two weeks later, typical brown lesions were observed on inoculated branches, and gum exuded from infected wounds. No symptoms were seen on the controls. Koch's postulates were fulfilled by reisolation of L. theobromae from diseased branches. L. theobromae is well documented as a pathogen of mango. In China, the disease was observed in the 1990s in Hainan Province, and the causal agents were identified as L. theobromae and Colletotrichum gloeosporioides Penz. & Sacc based on morphological observation (3). To our knowledge, this is the most severe outbreak reported from China. References: (1) V. S. de Oliveira Costa et al. Eur. J. Plant Pathol. 127:509, 2010. (2) F. Wang et al. Plant Dis. 95:1378, 2011. (3) Q. C. Xiao et al. Tropical Crops Research (in Chinese) 2:25, 1995.