(Wiley, 2023) Barco Antoñanzas, María; Font Farre, María; Eceiza, Mikel Vicente; Gil Monreal, Miriam; Van der Hoorn, Reiner; Royuela Hernando, Mercedes; Zabalza Aznárez, Ana; Institute for Multidisciplinary Research in Applied Biology - IMAB; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
The herbicides glyphosate and pyrithiobac inhibit the enzyme 5-enolpyruvylshikimate3-phosphate synthase (EPSPS) in the aromatic amino acid biosynthetic pathway and
acetolactate synthase (ALS) in the branched-chain amino acid biosynthetic pathway,
respectively. Here we characterise the protease activity profiles of a sensitive (S), a
glyphosate-resistant (GR) and a multiple-resistant (MR) population of Amaranthus palmeri in response to glyphosate and pyrithiobac. Amino acid accumulation and cysteine
protease activities were induced with both herbicides in the S population and with pyrithiobac in the GR population, suggesting that the increase in cysteine proteases is
responsible for the increased degradation of the available proteins and the observed
increase in free amino acids. Herbicides did not induce any changes in the proteolytic
activities in the populations with target-site resistance, indicating that this effect was
only induced in sensitive plants.