Two roles of thylakoid lipids in modifying the activity of herbicides which inhibit photosystem II

Thesis/Dissertation · Tue Jan 01 00:00:00 EST 1985

OSTI ID:5073303

Kupatt, Jr, C C

Thylakoid lipids may modify the activity of herbicides which inhibit electron transport at the Q/sub B/ protein of photosystem II in two ways: (1) lipids can act as a hydrophobic barrier to a binding site localized close to the loculus of the membrane, and (2) changes in lipid composition can reduce the ability of inhibitors to block electron transport, possibly due to a change in the conformation of the Q/sub B/ protein. The herbicide binding site was localized close to the locular side of the thylakoid membrane by determining the activity of a number of substituted phenylurea and s-triazine herbicides in inverted and non-inverted thylakoids. Quantitative structure-activity relationship analysis showed that inversion of thylakoids reduced the requirement of molecular lipophilicity deemed necessary for phenylurea activity in non-inverted membranes, whereas s-triazines exhibited no differences in the lipophilicity requirement in thylakoid membranes of either orientation. The binding affinity of /sup 14/C-diuron was reduced in bicarbonate-depleted thylakoids relative to reconstituted or control membranes, as is the case with atrazine binding. These observations support a model of the herbicide binding site containing both common and herbicide family specific binding domains. Thylakoids isolated either from detached lambs quarters (Chenopodium album L.) leaves, treated with SAN 6706, or from soybean (Glycine max L.), with norflurazon or pyrazon applied preemergence, exhibited decreased susceptibility to atrazine. The ability of lipid-modifying treatments to decrease the atrazine susceptibility of field-grown soybeans was also investigated.

• Research Organization: Rutgers-the State Univ., New Brunswick, NJ (USA)
• OSTI ID: 5073303
• Resource Relation: Other Information: Thesis (Ph. D.)
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
LIPIDS
BIOCHEMISTRY
PHOTOSYNTHETIC MEMBRANES
STRUCTURE-ACTIVITY RELATIONSHIPS
PHOTOSYNTHETIC REACTION CENTERS
INHIBITION
CARBON 14 COMPOUNDS
CHLOROPLASTS
ELECTRON TRANSFER
GLYCINE HISPIDA
HERBICIDES
LEAVES
PLANTS
BACTERIA
CELL CONSTITUENTS
CHEMISTRY
LABELLED COMPOUNDS
LEGUMINOSAE
MEMBRANES
MICROORGANISMS
ORGANIC COMPOUNDS
PESTICIDES
RHIZOBIUM
550201* - Biochemistry- Tracer Techniques