Characterization of the physiological mechanisms for mesotrione tolerance in black oats (Avena strigosa Schreb)

• Grant number: 24/00076-1
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: April 01, 2024
• End date: November 30, 2025
• Field of knowledge: Agronomical Sciences - Agronomy - Crop Science
• Principal Investigator: Carlos Alberto Labate
• Grantee: Ana Júlia Faganello Dressano
• Host Institution: Escola Superior de Agricultura Luiz de Queiroz (ESALQ). Universidade de São Paulo (USP). Piracicaba , SP, Brazil

Abstract

Growing competitive cover crops such as black oats (Avena strigosa) during the off-season currently represents a promising alternative for improving the management of herbicide-resistant weed populations, nonetheless the few small number of registered herbicides for use in these crops impact their use and wide adoption. Recent research results have demonstrated black oats' tolerance to mesotrione herbicide, hence the objectives of this project are to determine (i) mesotrione tolerance levels in a commercial genotype and (ii) the underlying physiological mechanism which allows to crop to tolerate this herbicide. Experiments will be conducted in a greenhouse in order to determine tolerance levels through spraying with increasing rates of mesotrione (0.25 to 4X the labelled rate in a commercial product), either alone or mixed with the metabolic inhibitor malathion. Visual injury levels will be determined from 3-35 days after spraying as well as biomass at the latter. Afterwards, mesotrione absorption, translocation, and metabolic studies will be conducted at the Ecotoxicology lab (CENA/USP) in order to clarify the underlying tolerance mechanism. 14C-mesotrione will be applied to crop plants and these will be evaluated from 12-168h after treatment (HAT), when these will be washed to remove the unabsorbed herbicide, and translocation will be determined using plant autoradiography and tissue combustion. At 96 HAT, metabolites will be extracted from each plant, and their respective Rf obtained by thin layer chromatography and reading in radioscanners.