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.
Botrytis cinerea, which causes gray mold, is an important pathogen in four important economic crops, tomato, tobacco, cucumber and strawberry, in China and worldwide. Metabolic phenomics data on B. cinerea isolates from these four crops were characterized and compared for 950 phenotypes with a BIOLOG Phenotype MicroArray (PM). The results showed that the metabolic fingerprints of the four B. cinerea isolates were similar to each other with minimal differences. B. cinerea isolates all metabolized more than 17% of the tested carbon sources, 63% of the amino acid nitrogen substrates, 80% of the peptide nitrogen substrates, 93% of the phosphorus substrates, and 97% of the sulfur substrates. Carbon substrates of organic acids and carbohydrates, and nitrogen substrates of amino acids and peptides were the significant utilization patterns for B. cinerea. Each B. cinerea isolate contained 94 biosynthetic pathways. These isolates showed a large range of adaptabilities and were still able to metabolize substrates in the presence of the osmolytes, including up to 6% potassium chloride, 10% sodium chloride, 5% sodium sulfate, 6% sodium formate, 20% ethylene glycol, and 3% urea. These isolates all showed active metabolism in environments with pH values from 3.5 to 8.5 and exhibited decarboxylase activities. These characterizations provide a theoretical basis for the study of B. cinerea in biochemistry and metabolic phenomics and provide valuable clues to finding potential new ways to manage gray mold.
Tobacco (Nicotiana tabacum L.) is a leafy, annual, solanaceous plant grown commercially for its leaves in China. In continuing research on foliar diseases of tobacco in Guizhou province in August 2019, diseased leaves of tobacco that had sandy beige, elliptical or irregular shaped lesions, with brown in edge, and surrounded by yellow halos on 40% of leaves on 5% plants were obtained (cv. Yunyan 87) in Zhenan (28.55° N, 107.43° E), Guizhou, China (Fig. 1A, 1B). Diseased leaf segments were surface sterilized and plated on potato dextrose agar (PDA). Isolate (T41) was selected for identification. The colonies had white aerial hyphae, with orange-red on the underside when cultured on PDA (Fig. 1G, 1H). The colonies had woolly aerial hyphae, white to grey eventually, and produced pycnidia on oatmeal agar (OA) (Boerema et al. 2004) (Fig. 1I, 1J). Pycnidia were dark, spherical or flat spherical, and 69.2-178.0 µm in diameter. Conidia were oval mostly, aseptate, usually guttulate, and the size was 5.0 - 6.5 µm × 3.2 - 5.4 µm (Fig. 1K, 1L). The rDNA internal transcribed spacer region (ITS) with primers ITS1f/ITS4 (White et al. 1990; Gardes and Bruns 1993), 28S ribosomal RNA gene (LSU) with primers LROR/LR7 (Rehner and Samuels 1994), beta-tubulin gene (TUB2) with primers Btub2Fd/Btub4Rd (Woudenberg et al. 2009) and RNA polymerase II second largest subunit gene (RPB2) with primers RPB2-5F2/fRPB2-7cR (Liu et al. 1999) of T41 were sequenced (GenBank accession numbers were MN704804, MN710367, MN718012 and MN718013, respectively). Maximum Likelihood (ML) analyses and Bayesian Inferences (BI) analyses based on concatenated these four sequences were conducted with RAxML v. 7.2.6 and MrBayes v. 3.2.1, respectively, which showed that T41 comprised a clade with Epicoccum latusicollum strains (CGMCC 3.18346 and LC 8153) (ML/BI = 100/1) (Fig. 2). Based on morphological and multi-gene molecular data, isolate T41 was identified as E. latusicollum described as a new taxon by Chen et al. (2017). To verify pathogenicity, tobacco plants at seedling stage (7-8 leaves) without visible disease were inoculated using conidial suspension (106 spores/ml), following Guo et al. (2020). All inoculated plants were maintained in a greenhouse with relative humidity ranging from 50% to 85% at 28 °C under a 12/12 h light/dark cycle. Seven days after incubation, typical symptoms were observed on inoculated leaves but not on control leaves (Fig. 1C, 1D, 1E, 1F). Koch's postulates were fulfilled by re-isolation of E. latusicollum from diseased leaves. E. latusicollum has been reported to cause black root on yam in China (Han et al. 2019). Meanwhile, there are many plants could be caused leaf spot by this genus, such as Lablab purpureus (Mahadevakumar et al. 2014) and Bletilla striata (Zhou et al. 2018). However, to the best of our knowledge, this is the first report of E. latusicollum causing leaf spot on tobacco in China. Because considerable loss occurred due to infection from E. latusicollum on tobacco leaves, this pathogen is worthy of further study and disease management practices need to be developed to prevent further losses.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.