First Report of Plumed Cockscomb (Celosia argentea var. plumosa) Stem Blight Caused by Phytophthora nicotianae in Taiwan.

Celosia spp. is a widely cultivated ornamental plant in gardens or parks in Taiwan. In September 2021, withering leaves and grayish-brown lesions were observed on the lower stem of plumed cockscombs (C. argentea var. plumosa) in Taichung City, with an incidence of about 22% in 136 plants after continuous precipitation, impacting the aesthetic value of the landscape. Symptomatic plants were collected, surface disinfected with 70% EtOH for ~20 sec., blotted dried, and excised diseased tissues (~ 3×3 mm2) were placed on 2% water agar. Four representative isolates were obtained after purification and the colonies were white with aerial and non-septated hyphae on V8 agar for 7 days. Sporangia were ovoid, ellipsoid or obpyriform, papillate, (26.3-55.9) 38.0 × 29.0 (20.1-40.6) µm (n = 200) (Ahonsi et al. 2007). Chlamydospores were spherical, terminal or intercalary, 26.0 (15.1-40.4) µm (n = 200). All isolates belong to A2 mating type with amphigynous antheridia and plerotic oospores, 21.0 (17.7-25.7) µm (n = 200), resembling the descriptions of Phytophthora (Erwin & Ribeiro 1996). For molecular identification, sequences of the ITS, ß-tubulin (ß-tub), and EF-1α regions of all isolates were amplified using ITS1/ITS4, TUBUF2/TUBUR1, and ELONGF1/ELONGR1 primers, respectively (White et al. 1990; Kroon et al. 2004). BLAST analyses of isolates cap1-2 (ITS: OQ581785; ß-tub: OQ590022; EF-1α: OQ590026), cap1-3 (ITS: OQ581786; ß-tub: OQ590023; EF-1α: OQ590027), cap2-1 (ITS: OQ581787; ß-tub: OQ590024; EF-1α: OQ590028), and cap2-2 (ITS: OQ581788; ß-tub: OQ590025; EF-1α: OQ590029) showed 100% of ITS identity, 99.5 to 99.9% of ß-tub identity, and 99.4 to 99.6% of EF-1α identity with Phytophthora nicotianae (ITS: MG865551; ß-tub: MH493987; EF-1α: MH359043). Phylogenetic trees were constructed using concatenated ITS, ß-tub, and EF-1α sequences based on maximum likelihood with a GTR+G model in MEGA X and Bayesian inference method in Geneious Prime 2022.2. All isolates were clustered in P. nicotianae with similar topology, thereby were identified as P. nicotianae. To confirm pathogenicity, 7 to 10-day-old seedlings and 6-week-old plumed cockscomb plants were inoculated in separate trials and each experiment was conducted twice. For each seedling, the lower stem was inoculated with 50 µl of zoospore suspension (104 zoospores/ml), 3 plants per isolate, and then incubated at 30±2℃ with 12 h light. For adult plants, each was inoculated with mycelial plugs from one V8 plate of 10-day-old P. nicotianae, 5 plants per isolate, and incubated at 25±2℃ in a greenhouse. Control plants were inoculated with sterile water and V8 agar plugs, respectively. Stem and root rot were observed on seedlings 4 days after inoculation while wilting and lower stem browning were observed on adult plants 2 months after inoculation. All control plants remained healthy at the end of repeated trials and identical pathogens were re-isolated only from symptomatic plants, thus fulfilling Koch's rules. P. nicotianae has been reported causing root rot and stem necrosis not only on cockscomb (C. plumosa Hort. ex Burvenich) in Argentina (Frezzi 1950), but also infecting several ornamental plants recently in Taiwan (Ann et al. 2018). To our knowledge, this is the first report of stem blight caused by P. nicotianae on plumed cockscombs in Taiwan. This finding suggests limited options for landscaping and the host preference of the isolates obtained in this study should warrant further studies.

Complete genome sequence of Agrobacterium pusense Bbcg2-2, a strain isolated from blueberry crown gall in Taiwan.

Agrobacterium pusense Bbcg2-2 is a strain isolated from a crown gall sample of blueberry (Vaccinium corymbosum) cultivar "Flicker" grown in Taiwan. The complete genome sequence of this bacterium consists of a 2,798,342-bp circular chromosome, a 2,140,031-bp linear chromid, and a 386,016-bp circular plasmid.

First Report of New Guinea Impatiens (Impatiens hawkeri) Leaf Spot Caused by Alternaria burnsii - A. tomato species complex in Taiwan.

New Guinea impatiens (Impatiens hawkeri) is a common ornamental crop usually planted in pots and planters, flower beds, home gardens, or parks in Taiwan. In June 2021, leaf spots on 87.1% (27/31) of potted I. hawkeri plants on National Chung Hsing University (NCHU) campus were observed. Initially, tiny chlorotic leaf spots were found, which aged into brown to grayish white necrotic spots with reddish-purple margins. The necrotic spots enlarged, coalesced, and formed concentric rings. To isolate the pathogen, diseased leaves were surface-disinfected with 70% ethanol for 15 seconds and blotted dry with a paper towel. Small pieces (~2×6 mm2) of tissues were excised from the junction of the lesions and healthy areas, placed onto 2% water agar, and incubated at 25°C with 12-h photoperiod for three days. Individual hyphal tips growing out of diseased tissues were transferred onto potato dextrose agar (PDA). Three isolates, OM10, OM43, and OM45, were obtained and grown on half-strength PDA at 28°C in the dark for at least two weeks. Conidia of each isolate produced on the half-strength PDA were washed off in sterile water with 0.01% of Tween 20. Pathogenicity tests were performed by spraying leaves of 2- to 3-month-old potted healthy I. hawkeri plants with 5 ml of conidial suspension (1 × 105 conidia/ml) of the three isolates, respectively. Control plants were sprayed with sterile water. There were four plants per treatment and the experiments were conducted twice. Inoculated plants were covered with plastic bags for two days and incubated in a greenhouse with a temperature range of 19 to 31°C. Leaf spots similar to those observed in the field were observed at 7 to 14 days after inoculation in both trials. The same fungus was isolated from inoculated plants, whereas control plants showed no symptoms. Thereafter, the three isolates were subjected to morphological and molecular identification. Colonies were brown to gray in the center and white in the border with abundant aerial mycelia. Conidia were brown, obclavate to ovoid, produced in single or branched chains, one to seven transverse and zero to three longitudinal septa. Conidial size of the three isolates ranged between 11.2 to 43.1 × 6.0 to 12.7 µm (n = 50 for each isolate). Conidiophores of the three isolates were dark-brown, septate, branched or unbranched, and measured 27.0 to 147.65 × 2.71 to 4.54 µm (n = 50 for each isolate). Based on the morphological characteristics, the three isolates were identified as Alternaria spp. (Simmons 2007). For molecular identification, the internal transcribed spacer (ITS) region, RNA polymerase II second largest subunit (RPB2), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), and major allergen Alt-a-1 gene (Alt-a-1) were amplified using primer pairs ITS1/ITS4 (White et al. 1990), RPB2-5F2/RPB2-7cR (Sung et al. 2007), gpd1/gpd2 (Berbee et al. 1999), and Alt-for/Alt-rev (Hong et al. 2005), respectively. Sequence analyses of isolates OM10 (ITS: GenBank Accession no. OP358436; RPB2: OP377483; GAPDH: OP377468; Alt-a-1: OP377471), OM43 (ITS: OP358437; RPB2: OP377484; GAPDH: OP377469; Alt-a-1: OP377472), and OM45 (ITS: OP358438; RPB2: OP377485; GAPDH: OP377470; Alt-a-1: OP377473) showed 100%, 99.61 to 100%, 99.65%, and 100% identities with a reference strain CBS 107.38 of A. burnsii for ITS (KP124420), RPB2 (KP124889), GAPDH (JQ646305), and Alt-a-1 (KP123967), respectively. They also showed 100%, 99.61 to 100%, 99.65%, and 99.58% identities with an A. tomato strain CBS 103.30 for ITS (KP124445), RPB2 (KP124915), GAPDH (KP124294), and Alt-a-1 (KP123991), respectively. Based on the morphological and sequence characteristics, the pathogen causing New Guinea impatiens leaf spot was identified as a member of the Alternaria burnsii - A. tomato species complex. The diseased plants on NCHU campus were destroyed. There have been no reports of the disease in other landscape areas or nurseries. To our knowledge, this is the first report of A. burnsii - A. tomato species complex causing New Guinea impatiens leaf spot in Taiwan. Since the pathogens in the species complex have been documented causing diseases on several important economic crops and the New Guinea impatiens is widely planted in nurseries and landscapes, the host range and the significance of the pathogen in agro-ecosystem may warrant further investigations.

Resistance to Fusarium oxysporum f. sp. luffae in Luffa Germplasm Despite Hypocotyl Colonization.

Fusarium wilt of Luffa, caused by Fusarium oxysporum f. sp. luffae, causes great losses in Luffa plants worldwide. In this study, 45 accessions of Luffa germplasm were used to determine their resistance to F. oxysporum f. sp. luffae isolates (FOLUST, FOLUSC, Fomh16, and Fol114) in two independent trials. In the first trial, only FOLUST was used to preliminarily identify resistant accessions. Nine accessions of Luffa acutangula and five of L. aegyptiaca were resistant to the FOLUST isolate. In the second trial, the other three isolates were then used to reevaluate the 14 resistant accessions. The results indicated that the 14 accessions were resistant to FOLUSC but exhibited variable resistance to the Fomh16 and Fol114 isolates. Eight accessions of L. acutangula and one accession of L. aegyptiaca were resistant to Fol114. Seven accessions of L. acutangula and one accession of L. aegyptiaca were resistant to Fomh16. Despite the lack of any symptoms, the F. oxysporum f. sp. luffae isolates were recovered from the hypocotyls of all resistant accessions at 28 days postinoculation, except for isolates FOLUSC and FOLUST on one accession (LA140). A high percentage (87.5%) of accessions collected from Bangladesh were identified as resistant, highlighting the effect of local adaptation on resistance. These results provide potentially valuable genetic resources for breeding programs to develop new varieties or rootstocks that could be beneficial for controlling soilborne diseases in different cucurbit crops and further investigating the mechanisms of resistance to F. oxysporum f. sp. luffae in Luffa plants.

Translocation of Fungicides and Their Efficacy in Controlling Phellinus noxius, the Cause of Brown Root Rot Disease.

Brown root rot disease (BRRD), caused by Phellinus noxius, is an important tree disease in tropical and subtropical areas. To improve chemical control of BRRD and deter emergence of fungicide resistance in P. noxius, this study investigated control efficacies and systemic activities of fungicides with different modes of action. Fourteen fungicides with 11 different modes of action were tested for inhibitory effects in vitro on 39 P. noxius isolates from Taiwan, Hong Kong, Malaysia, Australia, and Pacific Islands. Cyproconazole, epoxiconazole, and tebuconazole (Fungicide Resistance Action Committee [FRAC] 3, target-site G1) inhibited colony growth of P. noxius by 99.9 to 100% at 10 ppm and 97.7 to 99.8% at 1 ppm. The other effective fungicide was cyprodinil + fludioxonil (FRAC 9 + 12, target-site D1 + E2), which showed growth inhibition of 96.9% at 10 ppm and 88.6% at 1 ppm. Acropetal translocation of six selected fungicides was evaluated in bishop wood (Bischofia javanica) seedlings by immersion of the root tips in each fungicide at 100 ppm, followed by liquid or gas chromatography tandem mass spectrometry analyses of consecutive segments of root, stem, and leaf tissues at 7 and 21 days posttreatment. Bidirectional translocation of the fungicides was also evaluated by stem injection of fungicide stock solutions. Cyproconazole and tebuconazole were the most readily absorbed by roots and efficiently transported acropetally. Greenhouse experiments suggested that cyproconazole, tebuconazole, and epoxiconazole have a slightly higher potential for controlling BRRD than mepronil, prochloraz, and cyprodinil + fludioxonil. Because all tested fungicides lacked basipetal translocation, soil drenching should be considered instead of trunk injection for their use in BRRD control.

Identification and Characterization of a Multifunctional Biocontrol Agent, Streptomyces griseorubiginosus LJS06, Against Cucumber Anthracnose.

Twenty-eight bacterial strains isolated from Chinese herb extracts, beer fermentation waste, and raw oyster shells were evaluated for their efficacy in controlling cucumber anthracnose. Four bacterial strains, namely TG01, TG02, LJS06, and LJS08, were found to effectively reduce the mycelial growth of Colletotrichum orbiculare COC3 on PDA media. Spraying or drenching LJS06 spore suspension before inoculation significantly p < 0.05 reduced disease severity; thus, LJS06 was subject to further characterization. On the basis of the morphological, physiological, and biochemical characteristics and a multilocus sequence analysis of partial 16S rRNA, atpD, rpoB, and trpB genes, LJS06 was identified to be Streptomyces griseorubiginosus (Ryabova and Preobrazhenskaya) Pridham et al. Physiological and biochemical tests revealed that S. griseorubiginosus LJS06 can produce amylase, cellulase, chitinase, protease, siderophore, polyamines, and indole-3-acetic acid. Thus, a culture filtrate of LJS06 (specifically SL06) was formulated and evaluated for its efficacy against conidial germination, appressorium formation, and anthracnose management. Diluted SL06 was found to significantly (p < 0.05) inhibit conidial germination and appressorium formation, which can be attributed to impaired membrane integrity, accumulated reactive oxygen species (ROS), and impaired energy metabolism in the conidia. In addition, the spraying and drenching of diluted SL06 before inoculation consistently and significantly (p < 0.05) reduced anthracnose severity. These results jointly suggest that S. griseorubiginosus LJS06 can aid in the management of cucumber anthracnose by directly inhibiting conidial function and priming the plant defense system.

Prevalence and Epidemics of Neoscytalidium Stem and Fruit Canker on Pitahaya (Hylocereus spp.) in South Florida.

Since the 2000s, production of pitahaya (Hylocereus spp.) has increased significantly in South Florida. However, very limited information is available on the main diseases affecting this crop, particularly in regard to disease epidemiology and economic impact on the commodity. In this study, we surveyed five local pitahaya orchards and documented the most prevalent diseases and their causal agents. Three genera of fungal pathogens (Neoscytalidium, Alternaria, and Colletotrichum) were the major groups associated with symptoms on pitahaya cladodes (stems) during the early growing season. Among these, N. dimidiatum was identified as the most prevalent pathogen, with an overall isolation frequency of 29.8% (range, 13.9 to 47.2%). Hence, the temporal progress of N. dimidiatum stem canker infection was monitored and the relationship between stem canker intensity (incidence and severity) and fruit canker incidence was investigated. A significant positive correlation was found between fruit canker incidence and the standardized area under the disease incidence or severity curve on cladodes, suggesting that high stem canker intensity in the early season may contribute to high fruit canker incidence and thereby impact the aesthetic and market value of fruits. In vitro assays showed that both conidial germination and mycelial growth of N. dimidiatum are positively correlated with increasing temperature, with a maximum growth area at 32°C. This finding suggests a higher risk of infection, under an environment with high temperatures, which is common in South Florida. Data obtained in this study represent baseline knowledge for the future development of integrative management programs for controlling major diseases of pitahaya in South Florida.

Prognostic significance of parapharyngeal space venous plexus and marrow involvement: potential landmarks of dissemination for stage I-III nasopharyngeal carcinoma.

PURPOSE: To determine whether the parapharyngeal space venous plexus and marrow of the skull base bones are anatomic landmarks of the potential routes for the spread of disease for Stage I-III (American Joint Commission on Cancer 1997 staging system) nasopharyngeal carcinoma (NPC). METHODS AND MATERIALS: A total of 364 patients with NPC were enrolled in this study. The selection criteria were Stage I-III disease and primary radiotherapy at our hospital between 1990 and 2001. All patients had undergone MRI to evaluate the head-and-neck tumors. Patients who had undergone inadequate radiotherapy at a dose of <60 Gy and/or preradiotherapy chemotherapy before the imaging evaluation were excluded from the study. RESULTS: Of the 364 patients treated between 1990 and 2001, 163 (44.8%) had low-risk Stage I-III NPC (without parapharyngeal space extension or T3 disease). The 5-year distant metastasis-free survival rate, with and without adjuvant chemotherapy, was 97% and 96%, respectively. The remaining 201 patients had Stage II-III with parapharyngeal space extension or T3 disease. Their 5-year recurrence-free survival rate, with and without adjuvant chemotherapy, was 76.8% and 53.2% (p = 0.01), respectively. CONCLUSION: Our findings suggest that the risk of distant metastasis in Stage I-III NPC patients without parapharyngeal space extension or T3 disease is extremely low. Invasion into the parapharyngeal space venous plexus and marrow of the skull base bones is associated with distant metastasis, and involvement of these anatomic sites is considered a potential route for hematogenous disease spread in patients with Stage I-III NPC.

Colorectal cancer screening in asymptomaic adults: comparison of colonoscopy, sigmoidoscopy and fecal occult blood tests.

BACKGROUND AND PURPOSE: Fecal occult blood tests (FOBT) and flexible sigmoidoscopy have previously been recommended for colon cancer screening. More recently, studies have recommended colonoscopy due to the high rates of advanced neoplasm not detected by FOBT and sigmoidoscopy. Previous studies of the effectiveness of colonoscopic screening in Taiwan were limited to families of patients with colorectal cancer. This study compared colonoscopy, sigmoidoscopy and FOBT for colorectal cancer screening in asymptomatic adults. METHODS: Screening colonoscopies and FOBT were performed in asymptomatic adults enrolled in our health-screening program between January 1997 and December 2000. Advanced neoplasm was defined as the presence of a polyp larger than 1 cm, polyps with villous or severe dysplastic features, or cancer. The junction of the splenic flexure and descending colon was defined as the boundary of the proximal and distal colon, and it was presumed that the distal colon would be examined using sigmoidoscopy in all patients. Data on the prevalence of polyps, advanced neoplasm, and cancer among different age groups were obtained. The results of chemical and immunologic FOBT were compared. The anatomic distributions of advanced neoplasm and cancer were analyzed. RESULTS: A total of 7,411 colonoscopic examinations were included in the analysis. Advanced neoplasms were present in 93 examinations (1.3%), including 16 cancers (0.2%). Chemical FOBT detected 20.2% of advanced neoplasms and 37.5% of cancers. Immunologic FOBT detected 48.3% of advanced neoplasms and 87.5% of cancers. If sigmoidoscopy had been performed in place of colonoscopy, 26.9% of advanced neoplasms and 12.5% of cancers would not have been detected. CONCLUSIONS: Colonoscopy can detect neoplastic lesions undetectable by FOBT and sigmoidoscopy in asymptomatic subjects. These results suggest that colonoscopy should be the method of choice in colon cancer screening.