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Title: A MICROTECHNIQUE FOR THE ANALYSIS OF FREE AND CONJUGATED INDOLE-3-ACETIC ACID IN MILLIGRAM AMOUNTS OF PLANT TISSUE USING A BENCHTOP GC-MS1

Author
item RIBNICKY, DAVID - UNIVERSITY OF MARYLAND
item COOKE, TODD - UNIVERSITY OF MARYLAND
item Cohen, Jerry

Submitted to: Plant Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/25/1997
Publication Date: N/A
Citation: N/A

Interpretive Summary: Interpretive Summary Fruit growth and ripening are controlled be the interaction of several signaling compounds (plant hormones), the most important of which are auxin and ethylene. Reduction in auxin levels toward the end of fruit growth is a prelude to the start of a rapid series biochemical processes known as ripening. In order to develop and evaluate the technology to alter auxin levels in fruit, an ultrasensitive and precise method for analysis of auxin in very small tissue samples was developed. This method will be important for the development of improved genetic strategies for the production of tomato fruit with better ripening and postharvest qualities. These results will be useful to plant biochemists and molecular biologist interested in alteration of auxin for plant improvement and to consumers interested in the potential for obtaining improved crop plant varieties.

Technical Abstract: Technical Abstract A microtechnique was developed for the quantification of indole-3-acetic acid (IAA) in plant samples of one milligram fresh weight or less. The method permitted quantification of both free and conjugated IAA using a benchtop gas-chromatograph mass spectrometer. New methods for sample purification with high recovery at microscale levels together with simple changes that result in enhanced sensitivity of the instrumentation, allowed for a significant reduction in the amount of plant material required for analysis. Single oat coleoptile tips could be studied with this method and were found to contain free and total IAA levels of 137 and 399 pg/mg fresh weight, respectively. A single 5-day old Arabidopsis seedling was shown to contain 61 pg/mg fresh weight free IAA and 7850 pg/mg fresh weight of IAA following basic hydrolysis. This microtechnique provides a way to accurately measure IAA levels in very small structures and individual seedlings, thus making it a valuable research tool for elucidating the role and distribution of auxin in relation to growth and development.