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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Severity assessment in the Nicotiana tabacum-Xylella fastidiosa subsp. pauca pathosystem: design and interlaboratory validation of a standard area diagram set

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Pereira, Willian Eduardo Lino [1, 2] ; de Andrade, Sheila Maria Pereira [3] ; Del Ponte, Emerson M. [3] ; Esteves, Mariana Bossi [4] ; Canale, Maria Cristina [5] ; Takita, Marco Aurelio [1] ; Coletta-Filho, Helvecio Della [1] ; De Souza, Alessandra Alves [1]
Total Authors: 8
[1] Inst Agron Campinas, Ctr Citricultura Sylvio Moreira, BR-13490000 Cordeiropolis, SP - Brazil
[2] Univ Estadual Campinas, Inst Biol Genet & Biol Mol, BR-13083970 Campinas, SP - Brazil
[3] Univ Fed Vicosa, Dept Fitopatol, BR-36470900 Vicosa, MG - Brazil
[4] Univ Sao Paulo, Escola Super Agr Luiz de Queiroz, Dept Entomol & Acarol, BR-13418900 Piracicaba, SP - Brazil
[5] Empresa Pesquisa Agr & Extensao Rural Santa Catar, BR-89803904 Chapeco, SC - Brazil
Total Affiliations: 5
Document type: Journal article
Source: TROPICAL PLANT PATHOLOGY; v. 45, n. 6, SI NOV 2020.
Web of Science Citations: 0

Though an experimental host of Xylella fastidiosa, tobacco (Nicotiana tabacum) is an excellent plant model for biological and functional genomics studies of host-pathogen interactions involving X. fastidiosa. Symptoms induced by X. fastidiosa subsp. pauca on tobacco have been characterized, but severity assessment relies on an ordinal scale developed for symptoms on citrus. We designed a standard area diagram set (SADs) to aid in the visual estimation of percent area affected (% severity) and performed a multi-laboratory validation on tobacco cv. Havana, inoculated with X. fastidiosa subsp. pauca. Inoculated plants were monitored over time and digital images of the symptoms recorded. Three different software programs (APS Asses, ImageJ, and Leaf Doctor) were used to segment the images and calculate percent severity. Ten true-color images composed a 10-image SADs (0.5, 5, 10, 15, 25, 35, 45, 55, 65, and 75%). Fifty raters at four research groups (laboratories) assigned percent severity first without and then with the SADs on the same testing image set of 40 images following the same instructions provided by an examiner at each laboratory. The means of percent severity by all software programs were assumed to represent the actual percent severity given the perfect agreement between them. The unaided estimates were less precise, biased towards overestimation (up to 50% points) and less concordant among raters. Accuracy and precision varied considerably among the raters, and the effect of the SADs on the overall concordance to the actual severity was dependent on the laboratory; in all but one laboratory, the group means of the agreement index statistically improved. The between-rater agreement improved in all laboratories when using the SADs. The SADs may help to standardize and allow comparison across different laboratories, but care should be taken during instructions on how to discriminate symptoms that are not readily discernible as well as on how to correctly use the SADs. (AU)

FAPESP's process: 14/50880-0 - INCT 2014: comparative and functional genomics and citrus-assisted breeding
Grantee:Marcos Antonio Machado
Support Opportunities: Research Projects - Thematic Grants
FAPESP's process: 16/01273-9 - Toxin-antitoxin systems in Xanthomonas citri subsp citri: function and strategy for programmed cell death induction
Grantee:Paula Maria Moreira Martins
Support Opportunities: Scholarships in Brazil - Post-Doctoral
FAPESP's process: 13/10957-0 - Xylella fastidiosa-vector-host plant interaction and approaches for citrus variegated chlorosis and citrus canker control
Grantee:Alessandra Alves de Souza
Support Opportunities: Research Projects - Thematic Grants
FAPESP's process: 11/14629-2 - Nicotiana tabacum and Arabidopsis thaliana as models plants for functional study of genes associated with resistance to citrus variegated chlorosis.
Grantee:Willian Eduardo Lino Pereira
Support Opportunities: Scholarships in Brazil - Master