ARS | Publication request: 4-CHLOROINDOLE-3-ACETIC AND INDOLE-3-ACETIC ACIDS IN FRUITS AND ROOTS OF PISUM SATIVUM

Submitted to: Phytochemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 7, 1997
Publication Date: N/A

Interpretive Summary: Indole-3-acetic acid (IAA) is an important plant hormone that is found in all plants and in all plant tissues. In some plants, such as peas, a novel form of IAA, 4-CI-IAA, was also found. In order to understand the metabolism and activity of IAA and 4-CI-IAA better, we studied the distribution of both compounds in the pea plant and in pea fruit during development. 4-CI-IAA appears to be critically important to fruit growth in peas where it is uniquely required for pod elongation. This data will be useful to biochemists and plant breeders interested in improving fruit growth in peas and related crops plants. These results may also be of interest to scientists involved in studies of chemical regulation of fruit growth and could lead to improved techniques for chemical or genetic control of fruit size and/or quantity.

Technical Abstract: Endogenous IAA and 4-chloroindole-3-acetic acid (4-CI-IAA) were analyzed in vegetative and reproductive tissues of the garden pea (Pisum sativum L.) using gas chromatography-mass spectrometry selected ion monitoring in the presence of stable-isotope labeled internal standards. In fruit collected 3-8 days after anthesis (DAA) conjugates of both auxins were more abundant than the free hormones. Auxin levels (ng/g fr.wt) in the seeds are small at this stage, the pericarp nevertheless contained a substantial fraction of the overall quantity of IAA and 4-CI-IAA. While, in young fruit tissues, IAA was more abundant than 4-CI-IAA, the opposite was true for seeds at the "table-ready" stage and for roots of nine-day-old seedlings. Our data suggest that both IAA and 4-CI-IAA are required to coordinate the vegetative and reproductive growth of pea plants.