Assessment of acetolactate synthase (ALS) tolerance to imazethapyr in red rice ecotypes (Oryza spp) and imidazolinone tolerant/ resistant rice (Oryza sativa) varieties

Abstract

Three red rice ecotypes (Oryza spp), including LA 5, MS 5 and TX 4, were evaluated for acetolactate synthase resistance/tolerance to imazethapyr. The red rice ecotypes were compared with a tolerant line (CL-121), a resistant line (CL-161) and a conventional rice variety (Cypress). Based on enzymatic activity, the mean I(50) values were 1.5, 1.1, 1.5, 1.6, 20.8 and 590.6 microM imazethapyr, respectively, for LA 5, MS 5, TX 4, Cypress, CL-121 and CL-161. CL-161 was 32 times more resistant than CL-121 and at least 420 times more resistant than the average of the red rice ecotypes and Cypress. Results from the acetolactate synthase (ALS) assay showed that red rice ecotypes and Cypress had high susceptibility to imazethapyr when compared with the tolerant CL-121 and the resistant CL-161. Measurable enzymatic tolerance to ALS-inhibiting herbicides has not yet developed in these red rice ecotypes.

Resposta de biótipos de Euphorbia heterophylla a doses de glyphosate

“…Para utilização desse fator, foi necessário verificar o intervalo de confiança em nível de 95% do biótipo em estudo de menor tolerância, em relação aos demais. A sobreposição do intervalo de confiança do biótipo de menor tolerância em relação ao biótipo avaliado indica que não ocorreu diferença significativa entre C 50 dos biótipos (Avila et al, 2005).…”

Development and validation of a method using SPE and LC-ESI-MS-MS for the determination of multiple classes of pesticides and metabolites in water samples

“…The fact that they are frequently detected in the samples can be explained, for example, by the system of rice cultivation, which works with a variety of rice that is very resistant to the pesticides of the imidazolinones class; they are effective against red rice, the main pest in the irrigated rice plantation. 45 The fungicide tebuconazole and the herbicides atrazine and simazine were detected in the sampling since May, and the tebuconazole kept being detected in all samples. Triazines are used in the world as pre and post-emerging selective herbicides to control weeds in many cultures, such as corn, wheat, sugar cane and barley.…”

“…43 Besides, diuron and irgarol are used as antifouling in paints for vessels. 44,45 The association of these uses increase the contamination by diuron in waters, specially in portuary regions such as Rio Grande where there is intensive navigation. The presence of 3,4-DCA, the main metabolite of diuron and of propanil confirm the use of these compounds.…”

Field and laboratory assessments of sugarcane mutants selected in vitro for resistance to imazapyr herbicide

“…The IC 50 value of Mut1 was significantly higher than those of Mut2 and control N12; no other significant differences were recorded. By way of comparison, two commercially released imidazolinone-resistant rice mutants have been shown to exhibit IC 50 values of 13 and 369 times greater than non-mutant rice (Avila et al 2005). These rice mutants were considered tolerant and resistant, respectively.…”

“…Mut2 and Mut3 could be considered 'escapes' from the in vitro selection protocol. A more stringent in vitro selection protocol could be used in the future to increase the likelihood of obtaining mutants with greater levels of resistance, such as those seen in Clearfield ® rice cultivars (Avila et al 2005).…”