Characterization of acifluorfen selectivity mechanisms in tomato and related Lycopersicon species
Ricotta, Jacqueline Anne
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https://hdl.handle.net/2142/19597
Description
Title
Characterization of acifluorfen selectivity mechanisms in tomato and related Lycopersicon species
Author(s)
Ricotta, Jacqueline Anne
Issue Date
1990
Doctoral Committee Chair(s)
Masiunas, John B.
Department of Study
Crop Sciences
Discipline
Crop Sciences
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Biology, Plant Physiology
Language
eng
Abstract
Fourteen tomato (Lycopersicon esculentum) genotypes, Eastern Black nightshade, and 35 wild Lycopersicon accessions were screened for tolerance to acifluorfen. Response to acifluorfen was not species specific, but in general, the cultivated tomato varieties were slightly more tolerant than the wild accessions. From the genotypes initially screened, 15 with differential tolerance were chosen for further study depending on their fresh weight response to aciflourfen as well as their vigor rating after treatment. The relationship of trichome and stomate density, quantity of epicuticular wax and cuticle, and wax composition to acifluorfen tolerance was determined. There was no correlation between trichome density and acifluorfen tolerance or susceptibility, however, an inverse relationship between stomate density and tolerance was observed. Amount and composition of the epicuticular wax and the cuticle differed among genotypes, but did not correlate to acifluorfen tolerance.
Further investigations were conducted to determine the mechanism of selectivity within the genus. Absorption of $\sp{14}$C acifluorfen ranged from 4 to 14% after 48 hours, and 6 to 32% after one week, but uptake was not greater in susceptible genotypes. Translocation was minimal, and no metabolism occurred in any of the genotypes. Assays of chlororphyll content revealed differences among genotypes in amounts of chl A, chl B and total chl, but chlorophyll levels did not correlate to tolerance or susceptibility. Genotypes were screened for cross-tolerance to paraquat. All were susceptible, implying that enzymatic free radical protectant systems were not involved in acifluorfen tolerance. The toxic oxygen scavenger ascorbate was quantified. Tolerant genotypes Bellstar, Nova, and 204976 (an L. esculentum x L. pimpinellifolium hybrid) had lower levels of ascorbate than the susceptible genotypes, suggesting the involvement of antioxidants in acifluorfen selectivity in the Lycopersicon genus.
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