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Ultrastructural alterations to chloroplasts in triazine‐resistant weed biotypes
Author(s) -
Vaughn Kevin C.,
Duke Stephen O.
Publication year - 1984
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1984.tb02792.x
Subject(s) - chloroplast , biology , ultrastructure , chenopodium , atrazine , thylakoid , amaranthus hybridus , chlorophyll , botany , photosynthesis , abutilon , weed , stroma , agronomy , pesticide , biochemistry , immunohistochemistry , gene , immunology
Ultrastructural, morphometric and physiological techniques were used to determine the consistent chloroplast differences between triazine‐resistant (R) and triazine‐susceptible (S) biotypes of Amaranthus hybridus L., Chenopodium album L., and Brassica campestris L. All R biotypes had a larger proportion of the chloroplast volume as grana lamellae and a lower proportion of starch and stroma lamellae than S biotypes. In the R biotypes, a greater percentage of grana contain larger numbers of thylakoids per granum. A greater proportion of chlorophyll associated with the light‐harvesting chlorophyll alb protein and a lower chlorophyll alb ratio, traits associated with an increase in grana lamellae, were noted in R biotypes. Chloroplasts of S biotypes could be modified to ultrastructural phenocopies of those in R biotypes by treatment with sublethal levels of the PSII inhibiting herbicides, bentazon, diuron, atrazine and prometon. Despite the structural similarities to R biotypes, the modified S biotypes were not resistant to atrazine as determined by fluorescence measurements. Thus, the structural alterations observed are apparently secondary effects of impaired photosynthetic electron transport in R biotypes, and are not the cause of triazine resistance.