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Rapid photosynthetic and physiological response of 2,4-D–resistant Sumatran fleabane (Conyza sumatrensis) to 2,4-D as a survival strategy
- Jéssica F. L. Leal, Amanda dos S. Souza, Junior Borella, André Lucas S. Araujo, Ana Claudia Langaro, Monique M. Alves, Luana Jéssica S. Ferreira, Sarah Morran, Luiz H. S. Zobiole, Felipe R. Lucio, Aroldo F. L. Machado, Todd A. Gaines, Camila F. de Pinho
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- Journal:
- Weed Science / Volume 70 / Issue 3 / May 2022
- Published online by Cambridge University Press:
- 21 February 2022, pp. 298-308
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In this work, we evaluated the short time-induced oxidative stress–mediated rapid metabolic and physiological responses of resistant and susceptible Sumatran fleabane [Conyza sumatrensis (Retz.) E. Walker; syn.: Erigeron sumatrensis Retz.] to 2,4-D herbicide. Under fixed conditions (25 C and 65 ± 5% relative humidity), we assayed injury symptoms, chlorophyll a fluorescence, and antioxidative systems of biotypes both resistant and susceptible to 2,4-D (1,005 g ae ha−1). Under 15 versus 25 C temperatures and light and dark conditions, oxidative stress–mediated damage was assayed on plants that received 2,4-D herbicide applications. The injury symptoms observed in the 2,4-D–resistant biotype were rapid necrosis in leaves within 30 min, with the reestablishment of normal growth within 1 to 2 wk after 2,4-D treatment. The basal antioxidant enzyme activities of superoxide dismutase, catalase, and ascorbate peroxidase were greater in the resistant than in the susceptible biotype, although the activities of all enzymes generally did not differ between untreated and treated in the resistant biotype. The resistant biotype showed great reduction (at 1 and 4 h after application) in the photosynthetic electron transport chain performance index, while these metabolic changes were only detected after 4 h in the susceptible biotype. The resistant biotype recovered from the foliar damage 1 to 2 wk after 2,4-D application, while the susceptible biotype was controlled. The production of H2O2 was responsive to temperature and increased more rapidly in the 2,4-D–resistant biotype than in the susceptible one at both 15 and 25 C; however, there was a greater increase at 25 C in the resistant biotype. H2O2 production was not light dependent in 2,4-D–resistant C. sumatrensis, with increases even under dark conditions. The 2,4-D–resistant biotype showed rapid photosynthetic damage, possibly due to the rapid necrosis and leaf disruption, and increased H2O2 content compared with the susceptible biotype.
Sumatran fleabane (Conyza sumatrensis) resistant to PSI-inhibiting herbicides and physiological responses to paraquat
- Jéssica F. L. Leal, Amanda dos S. Souza, Junior Borella, André Lucas S. Araujo, Ana Claudia Langaro, Ana Carolina Chapeta, Eduardo S. Amorim, Gabriela S. Silva, Sarah Morran, Luiz Henrique S. Zobiole, Todd A. Gaines, Camila F. de Pinho
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- Journal:
- Weed Science / Volume 70 / Issue 1 / January 2022
- Published online by Cambridge University Press:
- 02 November 2021, pp. 46-54
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Herbicide-resistant weed management is one of the greatest agricultural challenges in crop production. Thus, the quick identification of herbicide-resistant weeds is extremely important for management. This study aimed to evaluate resistance to PSI-inhibiting herbicides (diquat) and physiological response to paraquat application in Sumatran fleabane [Conyza sumatrensis (Retz.) E. Walker; syn.: Erigeron sumatrensis Retz.]. The research was conducted with two C. sumatrensis biotypes, one susceptible and the other with multiple resistance to herbicides from five different modes of action (glyphosate, paraquat, diuron, saflufenacil, and 2,4-D). A dose–response assay was carried out to evaluate herbicide resistance to diquat in the paraquat-resistant C. sumatrensis biotype. The enzymatic activities of superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX), hydrogen peroxide (H2O2) content, and chlorophyll a (Chl a) fluorescence were measured in both biotypes after paraquat (400 g ai ha−1) application. The dose–response assay confirmed resistance of C. sumatrensis to diquat with resistance factor levels of 26-fold and 6-fold for LD50 and GR50 values, respectively, compared with the susceptible biotype. Accumulation of H2O2 occurred more rapidly in the paraquat-susceptible biotype than in the resistant one. Paraquat treatment caused an increase in SOD and APX activity in the susceptible biotype, but antioxidant enzyme activities were unaffected by paraquat in the resistant one at 5 h after application (HAA). Chl a fluorescence increased across the first 4 HAA in both resistant and susceptible biotypes. However, at 24 HAA, the resistant biotype showed a decline in fluorescence close to untreated plants, while the susceptible biotype died, confirming resistance to diquat in the paraquat-resistant C. sumatrensis biotype. The paraquat-resistant biotype does not induce antioxidative enzymes, as a possible mechanism of resistance to paraquat, but shows rapid recovery of photosynthesis and continuous growth when subjected to paraquat, while the paraquat-susceptible biotype does not survive.