Leaf rust caused by Cerotelium fici (Cast.) Arth. is the main disease affecting Moraceae family plants, such as Ficus and Morus species (Galleti and Rezende 2016; Srikantaswamy et al. 2006). In August 2020, rust symptoms were observed in 100% of mulberry (Morus nigra L.) trees in an experimental orchard (Piracicaba, SP, Brazil; 22°42’28”S, 47°37’42”W). Mulberry leaves with high rust severity became yellowish and fell-off prematurely. Pustules were light brown with yellowish halo and presented mean size of 0.9 mm2. Uredinial paraphyses (n = 50) measured 42.2 ± 0.67 µm long with wall uniformly ca 0.6-1.1 μm thick. Urediniospores were brownish, echinulate, globoid to broadly ellipsoid, and measured 27.1 ± 0.29 × 21.0 ± 0.27 µm with a wall thickness of 0.6 ± 0.01 µm (n = 100). The morphology of the urediniospores observed in this study was similar to that reported in the literature for C. fici on Morus alba and Ficus spp. (Gupta et al. 1994; McKenzie 1986; Hennen et al. 2005). We used a low-coverage genome-skimming approach to retrieve genetic information of the rRNA cluster and the mtDNA. Genomic DNA was extracted from 3-4 mg of stored urediniospores at -80 °C, macerated in liquid nitrogen, using a modified cetyl trimethylammonium bromide extraction procedure (Lo Piccolo et al. 2012), and sequenced with 150-bp paired-end reads on Illumina NovaSeq 6000 System. Raw data, (45,761,957 X 2 reads) were assembled with SPAdes v3.15.1 (Bankevich et al., 2012) and the output used to create a custom BLAST database. Loci used for the phylogenetic analyses were identified by BLASTn using, as a query, sequences of C. fici from Ficus sp. from Australia publicly available: Accession No. MH047210.1 for the rRNA and MW036502.1 for COX3. The retrieved sequences were deposited in GenBank under accession numbers OM296992 and OP797407 for the partial rRNA cluster and COX3, respectively. The Bayesian inference phylogenetic analysis of the three concatenate loci (18S, 28S, and COX3) revealed that the isolate obtained in this study (MN1) was clustered in a well-supported clade with C. fici type species. Pathogenicity tests were conducted using mulberry potted plants under greenhouse conditions (25 ± 5 °C). The urediniospores suspension (5 × 104 urediniospores ml-1) with 0.05% Tween 20 was sprayed with an airbrush on fully expanded leaves until run-off. As a control, mulberry plants were sprayed with distilled water and kept under the same conditions. Inoculated and mock-inoculated plants were kept in a dark moist chamber at 23 °C (± 2 °C) for 24 h. After this period, plants were moved to the greenhouse. The experimental design was completely randomized with five replicates, each replicate consisted of one potted plant and the experiment was performed twice. At 12 days post-inoculation, all inoculated plants showed rust symptoms identical to those observed in the field, whereas control plants had no symptoms. The first symptoms were small pustules on the abaxial surface of fully expanded leaves. Small chlorotic lesions were observed on the adaxial leaf surface, which evolved into necrotic lesions. The pathogen was re-inoculated into potted plants, where it was maintained through monthly inoculations. To our knowledge, this is the first report of mulberry rust on M. nigra in Brazil. As mulberry leaves are the only natural food for silkworm (Bombyx mori L.), rust poses a significant threat to the sericulture industry because the disease can decrease production and quality of mulberry foliage.
Este Guia foi elaborado em 2020, para auxiliar as aulas remotas sobre diagnose de doenças de plantas. Nele, estão apresentados os sintomas e os agentes causais dos principais grupos de doenças de plantas que ocorrem nos estados do Sudeste do Brasil. A ordem em que os grupos de doenças de plantas aparecem no Guia segue a cronologia das aulas de Fitopatologia, ministradas na Escola Superior de Agricultura “Luiz de Queiroz” (ESALQ) da Universidade de São Paulo (USP). Como introdução a cada grupo de doenças, elaborou-se um breve texto sobre a importância daquele grupo, informações sobre o ciclo de relações patógeno-hospedeiro e um mapa com a distribuição mundial de uma das doenças típicas do grupo. Esta publicação não tem a pretensão de apresentar a sintomatologia de todas as doenças de plantas que ocorrem nas principais culturas do Sudeste brasileiro, e não pode abordar cada doença em detalhes. O objetivo é auxiliar o ensino da diagnose a alunos do curso de Engenharia Agronômica.
Esta segunda edição do Guia de Diagnose para Aulas Práticas de Fitopatologia é uma versão revisada e ampliada do primeiro Guia, elaborado em 2020 para auxiliar as aulas remotas sobre diagnose de doenças de plantas. Desta vez, o Guia servirá de auxílio às aulas presenciais, pois, nele, estão apresentados os sintomas e os agentes causais dos principais grupos de doenças de plantas que ocorrem nos estados do Sudeste do Brasil. Como introdução a cada grupo de doenças, há um breve texto sobre a importância daquele grupo, informações sobre o ciclo de relações patógeno-hospedeiro e um mapa com a distribuição mundial de uma das doenças típicas do grupo. Além da inclusão de novas imagens de plantas sintomáticas e de estruturas patogênicas, esta edição apresenta também as sequências utilizadas no preparo de lâminas para visualização de estruturas fúngicas e bacterianas ao microscópio de luz. Esta publicação busca auxiliar o ensino da diagnose a alunos do curso de Engenharia Agronômica.
The demands of high-quality zucchini fruits by the consumer market make studies regarding the improvement of cultivation systems, such as plant nutrition and salinity tolerance. Considering the demands of the consumer market for the high quality of zucchini fruits, it is necessary studies regarding the improvement of production systems for this improvement, such as nutrition and salinity tolerance to plant. Thus, this study aimed to evaluate the zucchini fruits quality characteristics, grown in soilless, under N:K ratios, and levels of electrical conductivity of the nutrient solution. The experiment was conducted in a protected environment in pots with 8.2 dm³ of volumetric capacity filled with commercial substrate. The trial design adopted was randomized blocks, with three replicates, in a 5x3 factorial scheme, with five levels of electrical conductivity (1.0; 2.0; 3.0; 4.0; and 5.0 dS m -1 ) and three N:K ratios (2:1; 1:1; and 1:2), both in the nutrient solution. The application of the nutrient solution was by fertigation through drip irrigation. Throughout the experiment, variables related to fruit quality and total plant biomass production were analyzed. The HIGHLIGHTS• Electrical conductivity (EC) and N:K ratios modify zucchini fruit size.• Organoleptic characteristics of zucchini fruits increase with EC.• Total dry mass production of plants showed interaction between N:K ratio and EC.
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