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Taxonomic resolution of fleabane species (Conyza spp.) based on morphological and molecular markers and their dispersion across soybean-cropping macroregions and seasons in Brazil

Published online by Cambridge University Press:  29 January 2024

Augusto Kalsing*
Affiliation:
Graduate Student, Postgraduate Group of Crop Protection, São Paulo State University, Botucatu, SP, Brazil; current: Researcher, Corteva Agriscience, Crop Protection Discovery and Development, Mogi Mirim, SP, Brazil
Felipe A. Nunes
Affiliation:
Researcher, Corteva Agriscience, Crop Protection Discovery and Development, Mogi Mirim, SP, Brazil
Guilherme A. Gotardi
Affiliation:
Researcher, Corteva Agriscience, Crop Protection Discovery and Development, Mogi Mirim, SP, Brazil
Jaqueline B. Campos
Affiliation:
Researcher, Corteva Agriscience, Crop Protection Discovery and Development, Mogi Mirim, SP, Brazil
Angelo A. Schneider
Affiliation:
Professor, Biological Sciences Department, Pampa Federal University, São Gabriel, RS, Brazil
Leandro Tropaldi
Affiliation:
Professor, Agricultural and Technological Sciences Department, São Paulo State University, Dracena, SP, Brazil
Edivaldo D. Velini
Affiliation:
Professor, Crop Protection Department, São Paulo State University, Botucatu, SP, Brazil
Aldo Merotto Jr
Affiliation:
Professor, Crop Science Department, Federal University of Rio Grande do Sul, Porto Alegre, RS, Brazil
Caio A. Carbonari
Affiliation:
Professor, Crop Protection Department, São Paulo State University, Botucatu, SP, Brazil
*
Corresponding author: Augusto Kalsing; Email: augusto.kalsing@corteva.com

Abstract

The Conyza genus includes nearly 150 species, comprising closely related weedy species. Proper identification of Conyza spp. is essential to develop effective strategies for their management. The overlap of traits, species varieties, and the putative occurrence of hybridization hampers the identification of Conyza spp. and its management in agricultural and natural environments. Herein, we assessed five DNA barcodes and 32 morphological traits to classify Conyza spp. and survey their dispersion in soybean fields [Glycine max (L.) Merr.] in Brazil in 2019, 2020, and 2021. The Conyza accessions included two species, hairy fleabane [Conyza bonariensis (L.) Cronquist) and Sumatran fleabane [Conyza sumatrensis (Retz.) E. Walker], and each species comprised two varieties. The ITS and rps16-trnQ gene regions showed the ability to distinguish between the two Conyza species, while the matK, rbcL, and trnF-trnF gene regions were not polymorphic. Out of 32 morphological traits, phyllary color, involucre shape, capitulescence type, and inflorescence type were the most polymorphic and even reliable for taxonomic purposes. The combination of ITS or ITS+rps16-trnQ regions and the four morphological markers was able to discriminate 91% of the plants, except those of C. bonariensis var. angustifolia. These results support the taxonomic resolution between C. bonariensis and C. sumatrensis and are useful for other Conyza spp. and other closely related weedy species worldwide. Conyza sumatrensis was detected in 94% of soybean fields across macroregions and seasons in Brazil, while C. bonariensis was sparsely dispersed, mainly in the southern macroregion (MRS 1).

Information

Type
Research Article
Copyright
© The Author(s), 2024. Published by Cambridge University Press on behalf of Weed Science Society of America

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