Response characterization and target site mechanism study in glyphosate-resistant populations of Lolium multiflorum L. from Brazil.

Italian ryegrass (Lolium multiflorum L.) is an invasive species widely spread in croplands worldwide. The intensive use of glyphosate has resulted in the selection of resistance to this herbicide in Italian ryegrass. This work characterized the response to glyphosate of Italian ryegrass populations from the South and Southwest regions of Paraná, Brazil. A total of 44 Italian ryegrass populations were collected in farming areas, and were classified for glyphosate resistance with 75% of populations resistant to gloyphosate. Of these, 3 resistant (VT05AR, MR20AR and RN01AR) and three susceptible (VT07AS, MR05AS and RN01AS) of these populations were selected to determine the resistance level and the involvement of the target site mechanisms for glyphosate resistance. Susceptible populations GR50 ranged from 165.66 to 218.17 g.e.a. ha-1 and resistant populations from 569.37 to 925.94, providing RI ranging from 2.88 and 4.70. No mutation in EPSPS was observed in the populations, however, in two (MR20AR and RN02AR) of the three resistant populations, an increase in the number of copies of the EPSPs gene (11 to 57×) was detected. The number of copies showed a positive correlation with the gene expression (R2 = 0.86) and with the GR50 of the populations (R2 = 0.81). The increase in EPSPS gene copies contributes to glyphosate resistance in Italian ryegrass populations from Brazil.

Essential oils of Tahiti lemon and cinnamon bark in control of storage fungi and the physiological and sanitary quality of beans / Óleos essenciais de limão Taiti e canela em casca no controle de fungos de armazenamento e na qualidade fisiológica e sanitária de feijão

With the objective to evaluate the efficiency of essential oils of Citrus latifolia (Tahiti lemon) and Cinnamomum zeylanicum (cinnamon bark) in the control of plant pathogens Penicillium sp. and Aspergillus sp. and the quality of the bean seeds, two experiments were conducted. In the first one, the effect of essential oils of C. latifolia and C. zeylanicum was evaluated in vitro development of the fungi Penicillium sp. and Aspergillus sp. and, in the second one, the influence of essential oils on the physiological and sanitary quality of bean seeds. The variables mycelial growth, conidial germination and sporulation of Penicillium sp. and Aspergillus sp. were measured in the first experiment, while the seed germination test, first count of germination, germination speed index (GSI) and sanity test of bean seeds were measured in the second. The essential oil (EO) of C. zeylanicum was more efficient than C. latifolia in the control of Aspergillus sp. and Penicillium sp., but decreased the physiological quality of the beans seeds. The fungal diversity identified in the seed health test was composed by fungi of the genera Aspergillus, Penicillium, Cladosporium, Fusarium, Chaetomium and Rhizopus. The results indicate the potential of the use of these EOs in the seeds treatment.(AU)

Com o objetivo de avaliar a eficiência dos óleos essenciais de Citrus latifolia (limão taiti) e Cinnamomum zeylanicum (canela em casca) no controle dos fitopatógenos Penicillium sp. e Aspergillus sp. e na qualidade das sementes de feijão, foram conduzidos dois experimentos. No primeiro, avaliou-se o efeito dos óleos essenciais de C. latifolia e C. zeylanicum no desenvolvimento in vitro dos fungos Penicillium sp. e Aspergillus sp. e, no segundo, a influência dos óleos essenciais sobre a qualidade fisiológica e sanitária das sementes de feijão. As variáveis crescimento micelial, germinação de conídios e esporulação de Penicillium sp. e Aspergillus sp. foram aferidas no primeiro experimento, enquanto o teste de germinação de sementes, primeira contagem de germinação, índice de velocidade de germinação (IVG) e teste de sanidade de sementes de feijão foram aferidas no segundo. O óleo essencial (OE) de C. zeylanicum foi mais eficiente que C. latifolia no controle dos fungos Aspergillus sp. e Penicillium sp., mas diminuiu a qualidade fisiológica das sementes de feijão. A diversidade fúngica identificada no teste de sanidade de sementes foi composta por fungos dos gêneros Aspergillus, Penicillium, Cladosporium, Fusarium, Chaetomium e Rhizopus. Os resultados indicam o potencial do uso desses óleos essenciais no tratamento de sementes.(AU)