Redox status regulation and action of extra- and intravascular defense mechanisms are associated with bean resistance ag

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ORIGINAL ARTICLE

Redox status regulation and action of extra- and intravascular defense mechanisms are associated with bean resistance against Fusarium oxysporum f. sp. phaseoli Felipe M. de Quadros 1 & Mateus B. de Freitas 1 & Carmen Simioni 2 & Chirle Ferreira 2 & Marciel J. Stadnik 1 Received: 22 February 2020 / Accepted: 4 June 2020 # Springer-Verlag GmbH Austria, part of Springer Nature 2020

Abstract Genetic resistance is the main strategy to control one of the most destructive diseases of common bean (Phaseolus vulgaris L), i.e., the Fusarium wilt caused by Fusarium oxysporum f. sp. phaseoli (Fop). However, little is known on host defense reactions in Fop-bean interaction. Thus, this work examined the defense mechanisms in root and hypocotyl tissues of common bean against Fop. Resistant and susceptible bean plants were inoculated by dipping their roots in a conidial suspension. Cross sections of roots and hypocotyls were observed in light microscopy at 1, 3, 6, and 9 days after inoculation (dai) to monitor Fop colonization, and at 3 and 9 dai to detect callose, carbohydrates, lipids, phenolics, and protein, and under electronic microscopy at 9 dai to observe ultrastructural changes in xylem cells. The content of hydrogen peroxide (H2O2), lipid peroxidation, and activity of the antioxidant enzymes ascorbate peroxidase (EC 1.11.1.11) and catalase (EC 1.11.1.6) were monitored spectrophotometrically in roots and hypocotyls at 0, 1, 3, 6, and 9 dai. Fop colonized inter- and intracellularly the epidermis and cortex reaching the xylem vessels faster in susceptible genotype. Fop inoculation induced phenolics and carbohydrates accumulation, callose deposition, and formation of occlusion material inside xylem vessels mainly in resistant genotype. Lipid peroxidation occurred mainly in susceptible plants. In contrast, the antioxidant enzymes seem to have contributed to reducing damage caused by H2O2 accumulation in resistant plants. This study gives evidences that inter- and intracellular physicochemical mechanisms can act together to delay Fop colonization in resistant plants. Keywords Fusarium wilt . Disease resistance . Histochemical/fluorescence reactions . Cell ultrastructure . Defense mechanisms

Abbreviations APX Ascorbate peroxidase BHT Butylated hydroxytoluene CAT Catalase CBB Coomassie brilliant blue CWA Cell wall apposition dai Days after inoculation

Handling Editor: Ulrike Mathesius * Felipe M. de Quadros [email protected] * Marciel J. Stadnik [email protected] 1

Laboratory of Phytopathology, Federal University of Santa Catarina, Florianopolis, SC 88034-001, Brazil

2

Plant Cell Biology Laboratory, Federal University of Santa Catarina, Florianópolis, SC 88049-900, Brazil

Fop FOX FW Fw H2O2 LHPO MDA ROS TBO TCA

Fusarium oxysporum f. sp. phaseoli Ferrous oxidation xylenol orange Fresh weight Fusarium wilt Hydrogen peroxide Lipid hydroperoxide Malondialdehyde Reactive oxygen species Toluidine blue O Trichloroacetic acid

Introduction Fusarium oxysporum Schlechtend.:Fr. f. sp. phaseoli JB Kendri