Pool of Resistance Mechanisms to Glyphosate in Digitaria insularis

• Published in: Journal of agricultural and food chemistry Vol. 60; no. 2; pp. 615 - 622
• Main Authors: de Carvalho, Leonardo Bianco, Alves, Pedro Luis da Costa Aguiar, González-Torralva, Fidel, Cruz-Hipolito, Hugo Enrique, Rojano-Delgado, Antonia María, De Prado, Rafael, Gil-Humanes, Javier, Barro, Francisco, Luque de Castro, María Dolores
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 18.01.2012
• Subjects: 3-Phosphoshikimate 1-Carboxyvinyltransferase - genetics; 3-Phosphoshikimate 1-Carboxyvinyltransferase - metabolism; Biological and medical sciences; Brazil; Digitaria - drug effects; Digitaria - physiology; Food industries; Fundamental and applied biological sciences. Psychology; Glycine - analogs & derivatives; Glycine - pharmacokinetics; Glycine - pharmacology; Glyoxylates - metabolism; Glyphosate; Herbicide Resistance; Herbicides - pharmacology; Isoxazoles; Mutation; Organophosphonates - metabolism; Plant Leaves - drug effects; Plant Leaves - metabolism; Sarcosine - metabolism; Shikimic Acid - analysis; Shikimic Acid - metabolism; Tetrazoles; mechanisms of resistance; EPSPS; N-phosphonomethylglycine; weed resistance; sourgrass; Resistance; Glyphosate; Mechanism
• ISSN: 0021-8561; 1520-5118
• DOI: 10.1021/jf204089d

Digitaria insularis biotypes resistant to glyphosate have been detected in Brazil. Studies were carried out in controlled conditions to determine the role of absorption, translocation, metabolism, and gene mutation as mechanisms of glyphosate resistance in D. insularis. The susceptible biotype absorbed at least 12% more 14C-glyphosate up to 48 h after treatment (HAT) than resistant biotypes. High differential 14C-glyphosate translocation was observed at 12 HAT, so that >70% of the absorbed herbicide remained in the treated leaf in resistant biotypes, whereas 42% remained in the susceptible biotype at 96 HAT. Glyphosate was degraded to aminomethylphosphonic acid (AMPA), glyoxylate, and sarcosine by >90% in resistant biotypes, whereas a small amount of herbicide (up to 11%) was degraded by the susceptible biotype up to 168 HAT. Two amino acid changes were found at positions 182 and 310 in EPSPS, consisting of a proline to threonine and a tyrosine to cysteine substitution, respectively, in resistant biotypes. Therefore, absorption, translocation, metabolism, and gene mutation play an important role in the D. insularis glyphosate resistance.