Глуфосинат: свойства, применение и воздействие на растения и здоровье.

Broad spectrum herbicide

Glufosinate (also known as phosphinothricin and often sold as an ammonium salt) is a naturally occurring broad spectrum herbicide produced by several species of Streptomyces soil bacteria. Glufosinate is a non selective, contact herbicide, with some systemic action. Plants may also metabolize bialaphos and phosalacine, other naturally occurring herbicides, directly into glufosinate. The compound irreversibly inhibits glutamine synthetase, an enzyme necessary for the production of glutamine and for ammonia detoxification, giving it antibacterial, antifungal and herbicidal properties. Application of glufosinate to plants leads to reduced glutamine and elevated ammonia levels in tissues, halting photosynthesis and resulting in plant death.

In the 1960s and early 1970s, scientists at University of Tübingen and at the Meiji Seika Kaisha Company independently discovered that species of Streptomyces bacteria produce a tripeptide they called bialaphos that inhibits bacteria; it consists of two alanine residues and a unique amino acid that is an analog of glutamate that they named "phosphinothricin". In the late 1980s scientists discovered enzymes in these Streptomyces species that selectively inactivate free phosphinothricin; the gene encoding the enzyme that was isolated from Streptomyces hygroscopicus was called the "bialaphos resistance" or "bar" gene, and the gene encoding the enzyme in Streptomyces viridochromogenes was called "phosphinothricin acetyltransferase" or "pat". Glufosinate also has shown to provide some protection against various plant diseases, as it also acts to kill fungi and bacteria on contact.

Genetically modified crops resistant to glufosinate were created by genetically engineering the bar or pat genes from streptomyces into the relevant crop seeds.

Phosphinothricin is a glutamine synthetase inhibitor that binds to the glutamate site. Glufosinate treated plants die due to a buildup of ammonia in the thylakoid lumen, leading to the uncoupling of photophosphorylation. Elevated levels of ammonia are detectable within one hour after application of phosphinothricin. The herbicide is also persistent; it has been found to be prevalent in spinach, radishes, wheat and carrots that were planted 120 days after the treatment of the herbicide.

There are no exposure limits established by the Occupational Safety & Health Administration or the American Conference of Governmental Industrial Hygienists. The WHO/FAO recommended acceptable daily intake (ADI) for glufosinate is 0.02 mg/kg. There are no exposure limits established by OSHA or the American Conference of Governmental Industrial Hygienists. It has been withdrawn from the French market since October 24, 2017 by the Agence nationale de sécurité sanitaire de l'alimentation, de l'environnement et du travail due to its classification as a possible reprotoxic chemical (R1b).