|Gimenez-Espinosa, Rosa - UNIV. CORDOBA, SPAIN|
|Plaisance, Kathryn - UNIVERSITY OF MINNESOTA|
|Deprado, Rafael - UNIV. CORDOBA, SPAIN|
Submitted to: International Weed Control Congress Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: June 25, 1996
Publication Date: N/A
Technical Abstract: Recent research conducted with pea (Pisum sativum L.) suggests that dicots are graminicide resistant due to the presence of a graminicide resistant, multisubunit (prokaryotic type) acetyl CoA carboxylase (ACCase) in plastids. There is also evidence that pea contains a cytosolic, multifunctional (eukaryotic type) ACCase that exhibits a moderate level of tolerance to the graminicides. Chickpea (Cicer arietinum L.) is a major grain legume crop in the Mediterranean area. We investigated whether both types of ACCase were present in chickpea and evaluated their tolerance to the graminicide diclofop. Crude extracts from leaves of chickpea were desalted and then applied to an FPLC anion exchange (Q Sepharose) column. Proteins were eluted with a salt (0 to 0.5 M KCl) gradient. Two peaks of ACCase activity were found. The first peak of ACCase activity eluted between 50 to 100 mM KCl and contained a 32 kDa biotinylated subunit. This speak, representing about 60% of the total ACCase activity, contained the multisubunit ACCase. The second peak, which eluted at approximately 200 mM KCl, contained the cytosolic, multifunctional ACCase as indicated by the presence of a 220 kDa biotinylated subunit. Herbicide concentrations required to inhibit ACCase activity by 50% (I50 values) were determined for diclofop for both the multisubunit and multifunctional ACCases. The multisubunit ACCase was resistant to diclofop with only 30% inhibition of activity at 100 uM. The multifunctional ACCase was moderately tolerant with an I50 value of approximately 3 uM. These results support the hypothesis that dicots are resistant to the graminicides because of the presence of the multisubunit, prokaryotic type ACCase in plastids.