Efeito transgeracional de doses sub-letais de glifosato e quizalofop e estresse por déficit hídrico na resposta de Eragrostis plana a ambos os herbicidas

Abstract

Eragrostis plana is the main invasive plant in the fields of the Pampa Biome. It is a highly invasive and competitive species with the native grassland, that tolerates several abiotic stresses and is difficult control. Plants subjected to abiotic stresses and herbicides can develop mechanisms that alleviate or reduce the damage caused by stressors and transmit this ability to the progenies. The objectives of this work were: 1) to investigate the effect of recurrent application of sub-letal rate of herbicides (quizalofop-p-ethyl or glyphosate) with or without drought stress for two generations may have developed reduction in sensitivity to the herbicide; 2) to investigate whether antioxidant enzymes are involved in this enhanced- reduction in sensitivity process; and 3) to investigate the main enhanced- reduction in sensitivity mechanisms in the development of resistance to glyphosate and quizalofop. F2 generation plants subjected to combined stress (drought stress and glyphosate sub-dose - DRYxGLY) showed the highest tolerance to glyphosate. Antioxidant enzymes in conjunction with the overexpression of EPSPS and the ABC MRP10 transporter are involved in increasing the tolerance of the DRYxGLY population to glyphosate. Generation F2 plants subjected to drought stress (named DRY) developed the highest tolerance to quizalofop. The increase in antioxidant enzyme activity together with the overexpression of the genes CYP72A31, CYP81A12 and GSTL2, are involved in the reduction of oxidative stress and possible metabolization of the herbicide, developing of reduction in sensitivity in the DRY population to quizalofop.