Efficacy of Chlorine-based, Enzymatic and Combined Chlorine-enzyme Treatments on Biofilm Removal

Glyphosate resistance evolution in weeds is a growing problem in world agriculture. Here, we have investigated the mechanism(s) of glyphosate resistance in a Lolium rigidum population (DAG1) from South Africa. Nucleotide sequencing revealed the existence of at least three EPSPS homologues in the L. rigidum genome and identified a novel proline 106 to leucine substitution (P106L) in 52% DAG1 individuals. This mutation conferred a 1.7-fold resistance increase to glyphosate at the whole plant level. Additionally, a 3.1-fold resistance increase, not linked to metabolism or translocation, was estimated between wild-type P106-DAG1 and P106-STDS sensitive plants. Point accepted mutation analysis suggested that other amino acid substitutions at EPSPS position 106 are likely to be found in nature besides the P106/S/A/T/L point mutations reported to date. This study highlights the importance of minor mechanisms acting additively to confer significant levels of resistance to commercial field rates of glyphosate in weed populations subjected to high selection pressure

Base molecular para resistência a fluazifop-p-butyl em capim-camalote (rottboellia cochinchinensis) da Costa Rica

Rottboellia cochinchinensis is an annual grass weed species known as itchgrass, or “caminadora” in America´s Spanish speaking countries, and has become a major and troublesome weed in several crops. The application of fluazifop-P-butyl at recommended rates (125 g a.i. ha-1) was observed to be failing to control itchgrass in a field in San José, Upala county, Alajuela province, Costa Rica. Plants from the putative resistant R. cochinchinensis population survived fluazifop-P-butyl when treated with 250 g a.i. ha-1 (2X label rate) at the three- to four-leaf stage under greenhouse conditions. PCR amplification and sequencing of partial carboxyl transferase domain (CT) of the acetyl-CoA carboxylase (ACCase) gene were used to determine the molecular mechanism of resistance. A single non-synonymous point mutation from TGG (susceptible plants) to TGC (putative resistant plants) that leads to a Trp-2027-Cys substitution was found. This Trp-2027-Cys mutation is known to confer resistance to all aryloxyphenoxyproprionate (APP) herbicides to which fluazifop-P-butyl belongs. To the best of our knowledge, this is the first report of fluazifop-P-butyl resistance and a mutation at position 2027 for a Costa Rican R. cochinchinensis population.Rottboellia cochinchinensis, espécie de planta daninha anual conhecida como capim-camalote, ou “caminadora”, em países de língua espanhola das Américas, tornou-se uma planta daninha significativa e problemática em diversas culturas. Observou-se que a aplicação de fluazifop-p-butyl nas doses recomendadas (125 g i.a. ha-1) não conseguiu controlar capim-camalote em uma região em San José, condado de Upala, província de Alajuela, Costa Rica. As plantas da população supostamente resistente de R. cochinchinensis sobreviveram a fluazifop-p-butyl quando tratadas com 250 g i.a. ha-1 (2X a dose do rótulo) na fase de três a quatro folhas em condições de estufa. Amplificação e sequenciamento de reação em cadeia da polimerase de domínio de transferase de ácido carboxílico parcial (TC) do gene acetil-CoA carboxilase (ACCase) foram utilizados para determinar o mecanismo molecular de resistência. Foi encontrada uma mutação de ponto não sinônimo individual de TGG (plantas suscetíveis) para TGC (plantas supostamente resistentes) que conduz a uma substituição de Trp-2027-Cys. Sabe-se que essa mutação de Trp-2027-Cys confere resistência a todos os herbicidas ariloxifenoxipropionatos (AFP) a que fluazifop-p-butyl pertence. Pelo visto, este é o primeiro relato de resistência a fluazifop-p-butyl de uma mutação na posição 2027 para uma população costarriquenha de R. cochinchinensisWest Florida Research and Education Center, University of Florida/[]//United States of AmericaUCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Agroalimentarias::Estación Experimental Agrícola Fabio Baudrit Moreno (EEAFBM