Identification and screening of fungicides against Piper nigrum basal Fusarium wilt disease in Hainan, China.

Fusarium wilt has occurred in the main Piper nigrum cultivation regions, which seriously affects the yield and quality of P. nigrum. To identify the pathogen of this disease, the diseased roots were collected from a demonstration base in Hainan Province. The pathogen was obtained by tissue isolation method and confirmed by pathogenicity test. Based on the morphological observation, sequence analyses of TEF1-α nuclear gene, Fusarium solani was identified as the pathogen causing P. nigrum Fusarium wilt and induced symptoms on inoculated plants, including chlorosis, necrotic spots, wilt, drying, and root rot. The experiments for the antifungal activity showed that all the 11 fungicides selected in this study showed certain inhibitory effects on the colony growth of F. solani, where 2% kasugamycin AS, 45% prochloraz EW, 25 g·L-1 fludioxonil SC and 430 g·L-1 tebuconazole SC exhibited relative higher inhibitory effects with EC50 as 0.065, 0.205, 0.395, and 0.483 mg·L-1 , respectively, and were selected to perform SEM analysis and test in seeds in vitro. The SEM analysis showed that kasugamycin, prochloraz, fludioxonil, and tebuconazole might have exerted their antifungal effect by damaging F. solani mycelia or microconidia. These preparations were applied as a seed coating of P. nigrum Reyin-1. The kasugamycin treatment was most effective in reducing the harmful impact of F. solani on the seed germination. These results presented herein provide useful guidance for the effective control of P. nigrum Fusarium wilt.

First Report of Pestalotiopsis clavispora causing Leaf Spot on Pandanus amaryllifolius in China.

Pandanus amaryllifolius, also known as pandan, is a perennial herb, growing in Indonesia, China and the Maluku Islands (Wakte et al. 2009). It is the only plant with aromatic leaves in the Pandanaceae. It is widely used in food, medicine, cosmetics and other industries, and is also known as "Oriental Vanilla." Pandan is planted in Hainan province over 1,300 ha and is the main plant intercropped among the forest trees. From 2020, the leaf spot was surveyed for three years. Diseased leaves occurred on 30 to 80% of the surveyed plants, with an incidence of 70% and yield losses of 40%. The disease occured from mid-November to April and was most severe at low temperatures and humidity. Initial symptoms were pale green spots, that formed dark brown, nearly circular lesions. As the lesions expanded, their centers became greyish white, with yellow halos at the junction of the diseased and healthy tissue. When the humidity was high, there were small black spots scattered in the center of the lesion. Symptomatic leaf samples were collected from four different sites. The leaf surface was disinfested with 75% ethyl alcohol for 30 s and washed with sterile distilled water three times. Samples from the junction of diseased and healthy tissue (0.5 × 0.5 cm) were removed and placed on potato dextrose agar (PDA) medium containing 100 µg/mL of cefotaxime sodium and cultivated in a dark incubator at 28°C. After two days, hyphal tips from the edges of growing colonies were transferred to fresh PDA plates for further purification. Following Koch's postulates, colonies from strains were used as inoculum in pathogenicity tests. Colonies with 5 mm diameter were inoculated upside onto fresh and healthy pandan leaves via wounding method (pinpricked by sterilized needles) and non-wounding method. Sterilized PDA was used as control. All plants were setted three replicates and were incubated at 28℃ for 3 to 5 days. When symptoms on leaves similar to those in the field appeared, the fungus were reisolated The colonies formed on PDA were also consistent with the original isolate (Scandiani et al, 2003). After seven days, the colony covered the whole petri dish with white, petal-shaped growth with a slight concentric, annular bulge in the center, irregular edges, with black acervuli emerging at a later stage of colony growth. Conidia were fusiform, 18.1±1.6 × 6.4±0.3 µm, showing four septations and five cells, the middle three cells were brownish black to olivaceous, and the apical cell colorless with two to three filaments, 21.8±3.5 µm long. The caudate cell was colorless with one stalk 5.9±1.8 µm long (Zhang et al. 2021; Shu et al. 2020). According to the colony and conidia characteristics, the pathogen was initially identified as Pestalotiopsis spp. (Benjamin et al. 1961). To confirm the pathogen identity, we used the universal primers ITS1/ITS4, targeting primers EF1-728F/EF1-986R and Bt2a/Bt2b sequences (Tian et al. 2018). The sequences of the PCR products were deposited in NCBI GenBank with accession numbers OQ165166 (ITS), OQ352149 (TEF1-α) and OQ352150 (TUB2). BLAST results showed that the sequences of the ITS, TEF1-α and TUB2 genes shared 100% homology with the sequences of Pestalotiopsis clavispora. The maximum likelihood method was used in the phylogenetic analysis. The result showed that LSS112 was clustered with Pestalotiopsis clavispora with a support rate of 99%. Based on morphological and molecular characteristics, the pathogen was confirmed as Pestalotiopsis clavispora. To our knowledge, this is the first report of leaf spot of pandan caused by Pestalotiopsis clavispora in China. This research will be immediately helpful for the diagnosis and control the disease on pandan.

Pre-operative predictive factors for intra-operative pathological lymph node metastasis in rectal cancers.

BACKGROUND: A number of clinicopathologic factors have been found to be associated with pathological lymph node metastasis (pLNM) in rectal cancer; however, most of them can only be identified by expensive high resolution imaging or obtained after surgical treatment. Just like the Child-Turcotte-Pugh (CTP) and the model for end-stage liver disease (MELD) scores which have been widely used in clinical practice, our study was designed to assess the pre-operative factors which could be obtained easily to predict intra-operative pLNM in rectal cancer. METHODS: A cohort of 469 patients who were treated at our hospital in the period from January 2003 to June 2011, and with a pathologically hospital discharge diagnosis of rectal cancer, were included. Clinical, laboratory and pathologic parameters were analyzed. A multivariate unconditional logistic regression model, areas under the curve (AUC), the Kaplan-Meier method (log-rank test) and the Cox regression model were used. RESULTS: Of the 469 patients, 231 were diagnosed with pLNM (49.3%). Four variables were associated with pLNM by multivariate logistic analysis, age<60 yr (OR=1.819; 95% CI, 1.231-2.687; P=0.003), presence of abdominal pain or discomfort (OR=1.637; 95% CI, 1.052-2.547; P=0.029), absence of allergic history (OR=1.879; 95% CI, 1.041-3.392; P=0.036), and direct bilirubin ≥ 2.60 µmol/L (OR=1.540; 95% CI, 1.054-2.250; P=0.026). The combination of all 4 variables had the highest sensitivity (98.7%) for diagnostic performance. In addition, age<60 yr and direct bilirubin ≥ 2.60 µmol/L were found to be associated with prognosis. CONCLUSION: Age, abdominal pain or discomfort, allergic history and direct bilirubin were associated with pLNM, which may be helpful for preoperative selection.