The fungus Myrothecium verrucaria (Alb. & Schwein.) (MV), originally isolated from diseased sicklepod (Senna obtusifolia L.), has bioherbicial activity against kudzu and several other weeds when applied with low c...The fungus Myrothecium verrucaria (Alb. & Schwein.) (MV), originally isolated from diseased sicklepod (Senna obtusifolia L.), has bioherbicial activity against kudzu and several other weeds when applied with low concentrations of the surfactant Silwet L-77. To more fully understand the initial events of MV infection or disease progression, and to improve knowledge related to its mechanism of action, the effects of MV and its product (roridin A) on kudzu seedlings were examined at the ultrastructural level. Ultrastructural analysis of MV effects on kudzu seedlings revealed a rapid (~1 h after treatment) detachment of the protoplast from the cell wall and plasmodesmata appeared to be broken off and retained in the wall. These symptoms occurred well in advance of the appearance of any fungal growth structures. Some fungal growth was observed after severe tissue degeneration (24 to 48 h after treatment), but this occurred primarily at the extra-cellular location with respect to the kudzu tissues. Kudzu seedlings treated with roridin A, a trichothecene produced by the fungus, exhibited some symptoms similar to those induced by the fungus applied in spore formulations with surfactant. The overall results are the first to report the ultrastructural effects of this bioherbicide on plants and suggest that penetration of a phytotoxic substance(s) in the fungal formulation was facilitated by the surfactant, and that roridin A exerts phytotoxicity toward kudzu.展开更多
The effects of Roundup </span><span><span style="font-family:Verdana;">WeatherMax</span><sup><span style="font-family:Verdana;"><sup>®</sup>&...The effects of Roundup </span><span><span style="font-family:Verdana;">WeatherMax</span><sup><span style="font-family:Verdana;"><sup>®</sup></span></sup></span></span><span><span><span style="font-family:Verdana;"> and </span><span style="font-family:Verdana;">Engame<sup>TM</sup></span></span></span><span><span><span style="font-family:Verdana;"> formulations of glyphosate were investigated on the cotyledons of glyphosate resistant (GR) and glyphosate sensitive (GS) isogenic cotton cultivars. </span><span style="font-family:Verdana;">Engame<sup>TM</sup></span></span></span><span><span><span style="font-family:Verdana;"> is a mixture of glyphosate and 1-aminomethanamide dihydrogen tetraoxosulfate (AMADS). Fully expanded cotton cotyledons treated with </span><span style="font-family:Verdana;">Engame<sup>TM</sup></span></span></span><span><span><span style="font-family:Verdana;"> or AMADS developed surface lesions within 2 hours after treatment whereas surfactant-treated control or </span><span><span style="font-family:Verdana;">WeatherMax</span><sup><span style="font-family:Verdana;"><sup>®</sup></span></sup></span></span></span><span><span><span style="font-family:Verdana;">-treated tissues did not develop lesions. The </span><span style="font-family:Verdana;">Engame<sup>TM</sup></span></span></span><span><span><span style="font-family:""><span style="font-family:Verdana;"> and AMADS damage appeared as depressions which were confirmed </span><span style="font-family:Verdana;">by scanning electron microscopy. Light micrographs of cross sections</span><span style="font-family:Verdana;"> through the depressions revealed collapsed and compressed epidermal and mesophyll cells with congealed cytoplasmic contents in the palisade and spongy mesophyll cells. Changes to photosynthetic electron transport were evident at 4 hours after treatment (HAT) in all treatments as revealed by chlorophyll A fluorescence. In GR cotton, the fluorescence perturbations decreased with time such that at 72 HAT </span></span><span style="font-family:Verdana;">Engame<sup>TM</sup></span></span></span><span><span><span style="font-family:Verdana;">-treated cotyledons could not be distinguished from the surfactant-or </span><span><span style="font-family:Verdana;">WeatherMax</span><sup><span style="font-family:Verdana;"><sup>®</sup></span></sup></span></span></span><span><span><span style="font-family:Verdana;">-treated plants. The GS cotton continued to show progressive decreases in the fluorescence parameters Fv/Fm and performance index (PI) to 72 HAT. Shikimate levels increased following glyphosate treatment in glyphosate sensitive cotton and </span><span style="font-family:Verdana;">Engame<sup>TM</sup></span></span></span><span><span><span style="font-family:Verdana;"> caused a two-to three-fold greater increase in shikimate compared to </span><span><span style="font-family:Verdana;">WeatherMax</span><sup><span style="font-family:Verdana;"><sup>®</sup></span></sup></span></span></span><span><span><span style="font-family:Verdana;">. These results indicate that the </span><span style="font-family:Verdana;">Engame<sup>TM</sup></span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">-based glyphosate formulation involved structural tissue damage which likely increased glyphosate uptake and subsequently increased inhibition of photosynthesis and the shikimate pathway.展开更多
文摘The fungus Myrothecium verrucaria (Alb. & Schwein.) (MV), originally isolated from diseased sicklepod (Senna obtusifolia L.), has bioherbicial activity against kudzu and several other weeds when applied with low concentrations of the surfactant Silwet L-77. To more fully understand the initial events of MV infection or disease progression, and to improve knowledge related to its mechanism of action, the effects of MV and its product (roridin A) on kudzu seedlings were examined at the ultrastructural level. Ultrastructural analysis of MV effects on kudzu seedlings revealed a rapid (~1 h after treatment) detachment of the protoplast from the cell wall and plasmodesmata appeared to be broken off and retained in the wall. These symptoms occurred well in advance of the appearance of any fungal growth structures. Some fungal growth was observed after severe tissue degeneration (24 to 48 h after treatment), but this occurred primarily at the extra-cellular location with respect to the kudzu tissues. Kudzu seedlings treated with roridin A, a trichothecene produced by the fungus, exhibited some symptoms similar to those induced by the fungus applied in spore formulations with surfactant. The overall results are the first to report the ultrastructural effects of this bioherbicide on plants and suggest that penetration of a phytotoxic substance(s) in the fungal formulation was facilitated by the surfactant, and that roridin A exerts phytotoxicity toward kudzu.
文摘The effects of Roundup </span><span><span style="font-family:Verdana;">WeatherMax</span><sup><span style="font-family:Verdana;"><sup>®</sup></span></sup></span></span><span><span><span style="font-family:Verdana;"> and </span><span style="font-family:Verdana;">Engame<sup>TM</sup></span></span></span><span><span><span style="font-family:Verdana;"> formulations of glyphosate were investigated on the cotyledons of glyphosate resistant (GR) and glyphosate sensitive (GS) isogenic cotton cultivars. </span><span style="font-family:Verdana;">Engame<sup>TM</sup></span></span></span><span><span><span style="font-family:Verdana;"> is a mixture of glyphosate and 1-aminomethanamide dihydrogen tetraoxosulfate (AMADS). Fully expanded cotton cotyledons treated with </span><span style="font-family:Verdana;">Engame<sup>TM</sup></span></span></span><span><span><span style="font-family:Verdana;"> or AMADS developed surface lesions within 2 hours after treatment whereas surfactant-treated control or </span><span><span style="font-family:Verdana;">WeatherMax</span><sup><span style="font-family:Verdana;"><sup>®</sup></span></sup></span></span></span><span><span><span style="font-family:Verdana;">-treated tissues did not develop lesions. The </span><span style="font-family:Verdana;">Engame<sup>TM</sup></span></span></span><span><span><span style="font-family:""><span style="font-family:Verdana;"> and AMADS damage appeared as depressions which were confirmed </span><span style="font-family:Verdana;">by scanning electron microscopy. Light micrographs of cross sections</span><span style="font-family:Verdana;"> through the depressions revealed collapsed and compressed epidermal and mesophyll cells with congealed cytoplasmic contents in the palisade and spongy mesophyll cells. Changes to photosynthetic electron transport were evident at 4 hours after treatment (HAT) in all treatments as revealed by chlorophyll A fluorescence. In GR cotton, the fluorescence perturbations decreased with time such that at 72 HAT </span></span><span style="font-family:Verdana;">Engame<sup>TM</sup></span></span></span><span><span><span style="font-family:Verdana;">-treated cotyledons could not be distinguished from the surfactant-or </span><span><span style="font-family:Verdana;">WeatherMax</span><sup><span style="font-family:Verdana;"><sup>®</sup></span></sup></span></span></span><span><span><span style="font-family:Verdana;">-treated plants. The GS cotton continued to show progressive decreases in the fluorescence parameters Fv/Fm and performance index (PI) to 72 HAT. Shikimate levels increased following glyphosate treatment in glyphosate sensitive cotton and </span><span style="font-family:Verdana;">Engame<sup>TM</sup></span></span></span><span><span><span style="font-family:Verdana;"> caused a two-to three-fold greater increase in shikimate compared to </span><span><span style="font-family:Verdana;">WeatherMax</span><sup><span style="font-family:Verdana;"><sup>®</sup></span></sup></span></span></span><span><span><span style="font-family:Verdana;">. These results indicate that the </span><span style="font-family:Verdana;">Engame<sup>TM</sup></span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">-based glyphosate formulation involved structural tissue damage which likely increased glyphosate uptake and subsequently increased inhibition of photosynthesis and the shikimate pathway.