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Subcellular localization of rice leaf aryl acylamidase activity
1Department of Biochemistry and Microbiology, Cook College, Rutgers-The State University of New Jersey, New Brunswick, New Jersey 08903.
Plant Physiology
|May 1, 1983
Summary
Rice plants possess immunity to the herbicide propanil thanks to aryl acylamidase. This enzyme, crucial for detoxification, is primarily located on the outer membrane of rice leaf mitochondria.
Area of Science:
- Plant biochemistry
- Molecular biology
- Agricultural science
Background:
- Rice (Oryza sativa) exhibits natural immunity to the herbicide propanil.
- Aryl acylamidase (aryl-acylamide amidohydrolase, EC 3.5.1.13) is known to hydrolyze and detoxify propanil.
- Understanding the enzyme's localization is key to explaining rice's herbicide resistance.
Purpose of the Study:
- To investigate the intracellular localization of aryl acylamidase in rice leaves.
- To determine the specific organelle and membrane fraction containing the enzyme responsible for propanil detoxification.
Main Methods:
- Isolation and fractionation of rice mesophyll protoplasts.
- Differential centrifugation to isolate cellular components.
- Density gradient centrifugation using Percoll for further separation.
- Biochemical marker analysis to assess purity of mitochondrial fractions.
Main Results:
- The highest specific activity of aryl acylamidase was found in the crude mitochondrial fraction.
- Further purification confirmed the enzyme's mitochondrial localization.
- Biochemical markers indicated minimal contamination in the purified mitochondrial fraction.
- Subfractionation of mitochondria localized the enzyme to the outer membrane.
Conclusions:
- Aryl acylamidase, responsible for propanil detoxification in rice, is located on the outer mitochondrial membrane.
- This specific localization contributes to the rice plant's inherent resistance to propanil herbicide.
- The findings provide a molecular basis for understanding herbicide immunity in crop plants.