First Report of Root and Bulb Rot Caused by Rhizoctonia solani AG-6 on Lanzhou Lily (Lilium davidii var. unicolor) in China.

Lanzhou lily (Lilium davidii var. unicolor) is the only famous sweet lily variety that has high edible, medicinal and ornamental value in China, which is mostly planted in the middle areas of Gansu Province in China. In recent years, severe yellowing and wilting of leaves, stem wilt, root and bulb rot symptoms were observed on Lanzhou lily in Qilihe District, Lanzhou, which has resulted in serious loss of bulb production. From June to August 2022, a survey of Lanzhou lily disease was carried out in Xiguoyuan and Weiling township of Qilihe District, Lanzhou. Typical symptoms of root and bulb rot were observed in Lanzhou lily fields. The disease incidence was estimated up to 30%. Fragments of symptomatic roots and bulbs were surface sterilized with 75% ethanol for 10 s, 2% sodium hypochlorite for 2 min, washed three times with sterilized distilled water, and then blotted dry on sterile filter paper. Fragments were placed on PDA medium and incubated at 25 ± 1°C in darkness for 5 days and 2 isolates were purified by the single-tip culture. Colonies of the fungus were white initially, and then turned light brown to brown, raised, and with entire or undulate edges. Sclerotia were brown and produced on PDA after 25 days of incubation at 25 ± 1°C in the dark. Genomic DNA from each of the two isolates was extracted, and the internal transcribed spacer (ITS) region was amplified and sequenced with the primer pair ITS5/ITS4 (White et al. 1990). The sequences of strains QLH22LD01 and QLH22LD02 were deposited in GenBank (OR710804 and OR710805). Phylogenetic analyses were performed using the Maximum Likelihood method with ITS sequences for anastomosis groups (AG) of Rhizoctonia solani. The phylogenetic tree grouped the two isolates within the R. solani AG-6 clade with high bootstrap support (100%). PCR analysis was performed with 21 primers specifically designed to detect individual anastomosis groups or anastomosis subgroups of R. solani (Carling et al., 2002; Misawa and Kurose, 2019; Misawa et al., 2020; Okubara et al., 2008). Among the 21 specific primer pairs, only AG-6 specific primer amplified the fungal DNA, indicating that the two isolates tested belonged to the R. solani AG-6. Therefore, these two strains were identified as R. solani AG-6. For pathogenicity tests, two isolates were grown individually on sterile wheat kernels at 25 ± 1°C for 14 days. Certified pathogen-free Lanzhou lily bulbs were grown in the plastic pot filled with the sterilized soil. Fifteen 2- week-old plants were inoculated by digging the soil and burying ten infested wheat kernels in the soil adjacent to the roots. Control plants were inoculated with sterile wheat kernels using the same procedure. All plants were placed in a greenhouse with a 12h/12h light/dark photoperiod at 15 to 30°C. Fifty days after inoculation, typical root and bulb rot symptoms developed on all inoculated plants, similar to symptoms observed in the field, whereas control plants remained symptomless. Pathogenicity test was performed three times with similar to symptoms observed in the field. Finally, the fungi were reisolated from the symptomatic plants and identified by molecular analysis as the isolates used for inoculation, thus fulfilling Koch's postulates. To our knowledge, this is the first confirmed report of R. solani AG-6 causing root and bulb rot on Lanzhou lily in China. Our findings improve knowledge about R. solani AGs occurring in Lanzhou lily fields in China. Due to serious damages caused by this disease in recent years in China, further studies should be conducted to investigate the diversity, prevalence, disease control measures and fungicide sensitivity of AGs distributed in the main Lanzhou lily-producing states in China.

First Report of Neck Rot Caused by Botrytis aclada on Onion (Allium cepa L.) in Gansu Province, China.

Onion (Allium cepa L.) is one of the most important cultivated vegetable crops in many countries, including China (Hanci 2018; Steentjes et al. 2021). Gansu, in the northwest region of China, is a major area of onion production (Zhang et al. 2022). In October 2021, typical symptoms of neck rot were observed on stored onion bulbs (cv. Honghe) in Jiuquan, Gansu Province, China. Further surveys of 20 bags of onion bulbs randomly selected in a storage facility with bulbs harvested from 73 ha indicated that approximately 5% of the bulbs had typical neck rot symptoms. The neck of infected bulbs developed a water-soaked decay, with softened and discolored inner scales with white to gray mycelium in the neck. Infection usually began in the neck and sometimes spread through the entire bulb. In severely affected bulbs, the fleshy scales were span style="font-family:'Times New Roman'">decayed and the bulbs had shrunk, with black sclerotia between the rotting scales in the neck and shoulders of the bulb. Small pieces cut from the margins of lesions were surface-disinfested with 75% ethanol for 10 s, and 1% NaClO for 1 min, rinsed three times in sterile distilled water, dried on sterile filter paper, placed onto potato dextrose agar (PDA), and incubated at 20 ± 1℃ for 5 days in the dark. Ten pure cultures were obtained by single-spore isolation (one from each of 10 bulbs). All 10 isolates produced colonies that initially were white, and became gray to dark in color with gray mycelium that was covered with abundant conidia resembling Botrytis species when cultured on PDA at 20 ± 1℃ for 10 days in the dark. Conidia (n = 100 per isolate) were one-celled, ellipsoid or ovoid, beige to dark brown, and 5.6 to 14.8 × 3.9 to 8.5 µm. Sclerotia were not produced by any of the isolates on PDA after incubation at 20 ± 1°C for 30 days. The internal transcribed spacer (ITS) region of ribosomal DNA, glyceraldehyde-3-phosphate dehydrogenase (G3PDH) gene, heat shock protein 60 (HSP60) gene, and DNA-dependent RNA polymerase II core subunit (RPB2) gene of two representative isolates, JQ21AC03 and JQ21AC09, were amplified and sequenced with primers ITS1/ITS4, G3PDH-F/G3PDH-R, HSP60-F/HSP60-R, and RPB2-F/RPB2-R, respectively (Staats et al. 2005), and deposited in GenBank (ITS: OP604277 and OP604283; G3PDH: OP627512 and OP627515; HSP60: OP627513 and OP627516; and RPB2: OP627514 and OP627517). BLASTn analysis of the resulting sequences showed 98 to 100% similarity with those of Botrytis aclada. A maximum likelihood phylogenetic tree generated by combining the sequenced loci using MEGA11.0, clustered isolates JQ21AC03 and JQ21AC09 with B. aclada with 99% bootstrap support. Based on these results, isolates JQ21AC03 and JQ21AC09 were identified as B. aclada. Pathogenicity of the two isolates on the onion cv. Honghe was confirmed by inoculating 30 heathy onion bulbs per isolate with 100 µL of conidial suspension (1×105 conidia/ml), while control bulbs were inoculated with 100 µL sterile distilled water. All 30 bulbs inoculated with each isolates developed neck rot symptoms after 30 days incubation at 15 ± 1ºC in the dark, with symptoms identical to those observed in the original storage facility, whereas control bulbs remained symptomless. The pathogen was re-isolated from the symptomatic tissue of inoculated bulbs, fulfilling Koch's postulates. hang et al (2008) documented this pathogen causing bulb rot of onions in Wuhan, Hubei Province, 1,700 km from Gansu. To the best of our knowledge, this is the first report of B. aclada causing neck rot on onion bulbs in storage in Gansu Province, which is the main onion production region in China. Considering that onion is the main source of income for growers in Gansu, further studies will be required to understand the epidemiology of this disease and foster appropriate disease management measures to avert disease outbreaks in the future.

First Report of Root Rot caused by Coniella fragariae on Paeoniae radix Rubra in China.

Paeoniae radix Rubra is a traditional Chinese herbal medicine, which has the effect of clearing heat and cooling blood, activating blood and removing stasis. It has become popular in the Chinese market in recent years due to its extremely high medicinal value and showy flower color. In May 2021, typical symptoms of root rot were observed in a field (35°7'12″ N, 103°58'48″ E) in Dingxi, Gansu province, China. Approximately 10% of the plants in the field had typical root rot symptoms, and the root of each affected plant is at least 5% severe. The roots of the naturally infected plants in the field discolored and decayed with black brown spots on the surface of the root bark, the root bark detached from the phloem，and some leaves were chlorosis, shrunken and smaller, and the branches were dead and underdeveloped. In the transverse section, the xylem was black diffusion and abnormal odor. Three diseased plants with typical symptoms were chosen at random and brought back to the lab. Small pieces cut from the margins of lesions were surface disinfested with 75% ethanol for 15 s, and 0.5% NaClO solution for 30 s, rinsed three times in sterile distilled water, dried on sterile filter paper, plaed onto potato dextrose agar (PDA), and incubated at 25 ± 1℃ for 7 days in the dark. The pure cultures were obtained by single-spore isolation. All isolates produced wavy on the surface, radial from the inside out, initially white or milky white to orange colonies with abundant black brown oily conidiomata pycnidia on PDA at 25 ± 1℃ after 15 days in the dark. The conidiomata pycnidia is spherical to irregularly spherical, 231.5 to 512.4 µm, initially transparent with age turning brown, with a dark brown internal conidial mass inside, and with a 13.1 to 45.4 µ m wide ostiole central. Young conidia (n=100) developed from conidiogenous cells, which were simple, tapering, hyaline, smooth, and 12.3 to 18.0 × 2.5 to 4.6 µm, 1.0 to 1.5 µm wide at apex. Mature conidia (n=100) were ellipsoid, apices tapering, subobtusely rounded, brown, and 6.5 to 11.0 × 4.1 to 7.5 µm. The morphological characteristics of the isolates were consistent with previous descriptions of the genus Coniella (Crous et al., 2014). A representation isolate CS-1 was deposited in the Institute of Plant Protection, Gansu Academy of Agricultural Sciences and used for further studies. To confirm the identity of the causal fungus, the internal transcribed spacer (ITS), 28S large subunit of nuclear ribosomal RNA (LSU) and partial translation elongation factor 1-alpha (TEF1-α) gene of the representative isolate CS-1 were amplified and sequenced using primers ITS1/ITS4 (White et al., 1990), LROR/LR7 (Chethan et al., 2017) and EF1-728F/EF1-986R (Carbone and Kohn, 1999), respectively, and deposited on GenBank with accession numbers OP824764 (ITS), OP824767 (LSU)/span>and OP903926 (TEF1-α). Blastn analysis of all sequences resulted in E-value of 0.0 (ITS and LSU) and nearly 0.0 (TEF1-α), with Query cover values of 90% to 99% identity with C. fragariae, confirming the hypothesis based on morphological features examination. To conduct a pathogenicity test, three root segments of healthy plants were wounded using sterilized needles and inoculated by pipetting 10 µL of conidial suspension (1×107 conidia/mL) onto each wound, and controls were inoculated with 10 µL sterile distilled water. These root segments were kept in a moist chamber at 25°C in the dark. The experiment was repeated three times. After 14 days, root rot symptoms were observed on all of the inoculated root segments and identical to those observed in the field, whereas control root segments did not develop symptoms. The pathogen was re-isolated from the lesions of inoculated root segments, fulfilling Koch's postulates. To the best of our knowledge, this is the first report of C. fragariae causing root rot on P. radix Rubra in China. This identification can aid in the selection of appropriate management measures for this disease.

[Effects of Nutrients on the Growth of Microcystis aeruginosa and Bacteria in the Phycosphere].

The "bacteria-algae" system plays an important role in water ecosystems. The effects of bacteria in phycospheres on the growth of Microcystis aeruginosa under in-situ nutrient stimulation were studied to explore the bacteria-algae interaction during a cyanobacteria bloom. The results showed that LB medium could inhibit the growth of M. aeruginosa, and the algicidal rate was 86.49%. Sodium acetate, glucose, and sodium citrate could promote M. aeruginosa, and the growth rate was more than 50%. The addition of nutrients in M. aeruginosa could have changed the biocoenosis in the phycosphere and increased the species richness by 16S rRNA gene sequencing, and the number of bacteria in the phycosphere increased dramatically in the LB medium and peptone groups. The physiological and biochemical responses showed that algae suffered serious lipid peroxidation, and superoxide dismutase (SOD) and catalase (CAT) activities first increased significantly and subsequently decreased under the oxidative stress of LB medium or peptone. Scanning electron microscopy (SEM) indicated that the surface of algae cells appeared wrinkled, invaded, and atrophied under LB medium stimulation, whereas bacteria in the phycosphere significantly increased. Furthermore, six strains of algicidal bacteria were isolated from the LB medium and peptone groups, and the algicidal rate of Bacillus sp. A1 was 97.55%, which confirmed that the phycosphere of M. aeruginosa included algicidal bacteria. Therefore, appropriate external nutrient stimulation can produce algicidal bacteria in situ to prevent cyanobacterial blooms.

First Report of Anthracnose Disease Caused by Colletotrichum fioriniae on Barbary wolfberry (Lycium barbarum L.) in Gansu Province, China.

Barbary wolfberry (Lycium barbarum L.) is a well-known edible and medicinal plant, widely grown in northwest China (Gao et al. 2021). During the summer of 2019, typical anthracnose symptoms were observed on fruits of barbary wolfberry in Baiyin, Gansu province, China. Approximately 30% of the barbary wolfberry fruits had typical anthracnose symptoms. Lesions on barbary wolfberry fruits were dark, circular or irregular, sunken, and necrotic or wilted, with the presence of orange to pink conidial masses under high humidity. Small pieces cut from the margins of lesions were surface disinfested with 75% ethanol for 10 s, and 1% NaClO solution for 1 min, rinsed three times in sterile distilled water, dried on sterile filter paper, placed onto potato dextrose agar (PDA), and incubated at 25 ± 1℃ for 5 days in the dark. The pure cultures were obtained by single-spore isolation. All isolates produced pale gray and dense aerial mycelia, in reverse orange to red, at times showing concentric rings on PDA at 25℃ after 10 days in the dark. Conidia (n=100) were colorless, smooth-walled, aseptate, fusiform elliptical with one or both ends, and 8.3 to 17.6 × 3.7 to 6.2 µm. Appressoria (n = 100) were solitary, pale to medium brown, smooth-walled, subglobose to elliptical, sometimes clavate or irregular, and 5.7 to 11.7 × 4.1 to 8.5 µm. The internal transcribed spacer (ITS) region of ribosomal DNA, glyceraldehyde-3-phosphate dehydrogenase (GAPDH) gene, bate-tubulin 2 (TUB2) gene, actin (ACT) gene, calmodulin (CAL) gene, chitin synthase 1 (CHS-1) gene, and histone H3 (HIS3) gene of the two representative isolates BY19LB02 and BY19LB06 were amplified and sequenced with primers ITS1/ITS4, GDF1/GDR1, T1/Bt2b, ACT-512F/ACT-783R, CL1/CL2A, CHS-79F/CHS-354R, CYLH3F/CYLH3R, respectively (Damm et al. 2012), and deposited on GenBank (ITS, MZ496816 and MZ505524; ACT, MZ557422 and MZ557417; CHS-1, MZ557423 and MZ557418; GAPDH, MZ557424 and MZ557419; HIS3, MZ557425 and MZ557420; TUB2, MZ557426 and MZ557421). BLAST analysis of the resulting for all the sequences showed 98 to 100% similarity with those of C. fioriniae. Based on the above, the isolates BY19LB02 and BY19LB06 were identified as C. fioriniae. To confirm the pathogenicity, detached heathy barbary wolfberry fruits were surface-sterilized with 75% ethanol for 30s, rinsed three times in sterile distilled water, allowed to dry on sterile filter paper, and then wounded using sterilized needles. Fruits were inoculated by pipetting 10 µL of conidial suspension (1×106 conidia/mL) onto each wound, and controls were inoculated with 10 µL sterile distilled water. Each treatment had 30 fruit replicates. These fruits were kept in a moist chamber at 28°C in the dark. The experiment was repeated three times. After 5 days, anthracnose symptoms were observed on all of the inoculated fruits and identical to those observed in the field, whereas control fruits did not develop symptoms. Theathogen was re-isolated from the lesions of inoculated fruits, fulfilling Koch's postulates. To the best of our knowledge, this is the first report of C. fioriniae causing anthracnose on barbary wolfberry in Gansu Province, China. The same disease on barbary wolfberry was reported in Jilin Province, China (Liu et al. 2016). Gansu is one of the main barbary wolfberry producing areas in northwest China and its geographical area, climate and environmental conditions are different from Jilin Province. Considering that barbary wolfberry is the main source of income for growers in Gansu, this identification can aid in the selection of appropriate management measures for this disease.

[Pollution Characterization and Comprehensive Water Quality Assessment of Rain-source River: A Case Study of the Longgang River in Shenzhen].

Rain-source urban rivers are an important part of the urban ecosystem. Due to the small water environment capacity and the rapid development of the regional economy and society, they are vulnerable to serious pollution. The goal of this study was to identify the main pollution characteristics of river water quality and to carry out a scientific comprehensive water quality assessment. Water samples from 12 sampling locations of the Longgang River in Shenzhen, a typical rain-source urban river, were collected from January to December in 2018. According to the Environmental Quality Standard for Surface Water (GB 3838-2002), 22 water quality indicators were analyzed, and the water quality of Longgang River was comprehensively evaluated using the single-factor assessment method, comprehensive pollution index method, and principal component analysis method. The results of the single-factor assessment method showed that water quality of all sampling sites of the Longgang River met the Class V of the Environmental Quality Standard for Surface Water (GB 3838-2002), and the Tiaojiao Shui and Longxi River met the Class Ⅳ and Class Ⅲ of the Environmental Quality Standard for Surface Water (GB 3838-2002), respectively. The results of the comprehensive pollution index method showed that the water quality of 12 sampling sites was clean or relatively clean. Both the results of the comprehensive pollution index and principal component comprehensive score showed that the water quality of Longxi River, Nanyue River, and Tianjiao Shui were the best among all sampling sites. There is still room for improvement in the Wutongshan River, Dakang River, Ailian River, Dingshan River, and Huangsha River, and significant consideration should be given to parameters such as nutrients (TN, TP, and NH4+-N), organic matter (COD and BOD5), fecal coliform, and anionic surfactants. The three methods were a combination of qualitative and quantitative evaluation. The results of each method were not identical. Thus, it is very necessary to explore the comprehensive water quality assessment using various methods for making scientific and reasonable water pollution control strategies.

Hangzhou criteria as downstaging criteria in hepatocellular carcinoma before liver transplantation: A multicenter study from China.

BACKGROUND: The downstaging of hepatocellular carcinoma (HCC) has been confirmed to benefit liver transplantation (LT) patients whose tumors are beyond the transplantation criteria. Milan criteria (MC), a tumor size and number-based assessment, is currently used as the endpoint in these patients. However, many studies believe that tumor biological behavior should be added to the evaluation criteria for downstaging efficacy. Hence, this study aimed to explore the feasibility of Hangzhou criteria (HC), which introduced tumor grading and alpha-fetoprotein in addition to tumor size and number, as an endpoint of downstaging. METHODS: We performed a multicenter and retrospective study of 206 patients accepted locoregional therapy (LRT) as downstaging/bridge treatment prior to LT in three centers of China. RESULTS: Recipients were divided into four groups: failed downstaging to the HC (group A, n = 46), successful downstaging to the HC (group B, n = 30), remained within the HC all the time (group C, n = 113), and tumor progressed (group D, n = 17). The 3-year HCC recurrence probabilities of groups B and C were not significantly different (10.3% vs. 11.6%, P = 0.87). The HCC recurrent rate was significantly higher in group A (52.3%) compared with that in group B/C (P < 0.05). Seven patients (7/76, 9.2%) whose tumor exceeded the the HC were successfully downstaged to the MC, and 39.5% (30/76) to the the HC. In group B, 23 patients remained beyond the MC and their survivals were as well as those of patients within the MC. CONCLUSIONS: Compared to the MC, HC downstaging criteria can give more HCC patients access to LT and furthermore, the outcome of these patients is the same as those matching MC downstaging criteria. Hangzhou downstaging criteria therefore is applicable in clinical practice.

[Allelopathic Effects and Allelochemicals of Myriophyllum elatinoides on Microcystis aeruginosa and Selenastrum capricornutum].

The allelopathic effects of Myriophyllum elatinoides on algal growth were investigated and potential allelochemicals secreted by Myriophyllum elatinoides were analyzed. Myriophyllum elatinoides were co-cultivated with different initial concentrations (105, 106, 107, 108, and 109 ind.·L-1) of Microcystis aeruginosa and Selenastrum capricornutum. The optical density of each group was measured daily. The results showed that 2.5 g·(200 mL)-1 of Myriophyllum elatinoides has significant inhibition effect on Microcystis aeruginosa growth with initial concentrations of 107 ind.·L-1 and 108 ind.·L-1. However, there was no significant inhibition on the growth of Selenastrum capricornutum. Through solvent extraction and GC-MS analysis, hexadecanoic acid was extracted and determined as an allelochemical in Myriophyllum elatinoides. Additionally, three potentially novel allelochemical compounds secreted by Myriophyllum elatinoides were determined as follows:3-ethyl-3-methylheptane, triethyl phosphate and dibutyl phthalate.

Antifungal Activity of Paenibacillus kribbensis Strain T-9 Isolated from Soils against Several Plant Pathogenic Fungi.

The bacterial strain T-9, which shows strong antifungal activity, is isolated from the soils of Samcheok, Gangwondo and identified as Paenibacillus kribbensis according to morphological and taxonomic characteristics and 16S rRNA gene sequence analysis. The P. kribbensis strain T-9 strongly inhibits the growth of various phytopathogenic fungi including Botrytis cinerea, Colletotricum acutatum, Fusarium oxysporum f. sp. radicis-lycopersici, Magnaporthe oryzae, Phytophthora capsici, Rhizoctonia solani, and Sclerotium cepivorum in vitro. Also, the P. kribbensis strain T-9 exhibited similar or better control effects to plant diseases than in fungicide treatment through in vivo assays. In the 2-year greenhouse experiments, P. kribbensis strain T-9 was highly effective against clubroot. In the 2-year field trials, the P. kribbensis strain T-9 was less effective than the fungicide, but reduced clubroot on Chinese cabbage when compared to the control. The above-described results indicate that the strain T-9 may have the potential as an antagonist to control various phytopathogenic fungi.

Biocontrol of fusarium crown and root rot and promotion of growth of tomato by paenibacillus strains isolated from soil.

In this study, bacterial strains were isolated from soils from 30 locations of Samcheok, Gangwon province. Of the isolated strains, seven showed potential plant growth promoting and antagonistic activities. Based on cultural and morphological characterization, and 16S rRNA gene sequencing, these strains were identified as Paenibacillus species. All seven strains produced ammonia, cellulase, hydrocyanic acid, indole-3-acetic acid, protease, phosphatase, and siderophores. They also inhibited the mycelial growth of Fusarium oxysporum f. sp. radicis-lycopersici in vitro. The seven Paenibacillus strains enhanced a range of growth parameters in tomato plants under greenhouse conditions, in comparison with non-inoculated control plants. Notably, treatment of tomato plants with one identified strain, P. polymyxa SC09-21, resulted in 80.0% suppression of fusarium crown and root rot under greenhouse conditions. The plant growth promoting and antifungal activity of P. polymyxa SC09-21 identified in this study highlight its potential suitability as a bioinoculant.

First Report of Potato Stem-End Rot Caused by Fusarium oxysporum in Korea.

In this study, we identified the causative agent of stem-end rot in potatoes that were grown in Gangwon alpine areas of Korea in 2013. The disease symptoms included appearance of slightly sunken circular lesion with corky rot on the potato surface at the stem-end portion. The fungal species isolated from the infected potatoes were grown on potato dextrose agar and produced white aerial mycelia with dark violet pigments. The conidiophores were branched and monophialidic. The microconidia had ellipsoidal to cylindrical shapes and ranged from 2.6~11.4 × 1.9~3.5 µm in size. The macroconidia ranged from 12.7~24.7 × 2.7~3.6 µm in size and had slightly curved or fusiform shape with 2 to 5 septate. Chlamydospores ranged from 6.1~8.1 × 5.7~8.3 µm in size and were present singly or in pairs. The causal agent of potato stem-end rot was identified as Fusarium oxysporum by morphological characterization and by sequencing the internal transcribed spacer (ITS1 and ITS4) regions of rRNA. Artificial inoculation of the pathogen resulted in development of disease symptoms and the re-isolated pathogen showed characteristics of F. oxysporum. To the best of our knowledge, this is the first study to report that potato stem-end rot is caused by F. oxysporum in Korea.