| Research Abstract |
We studied on the synthesis and the physiological activities of the novel plant growth regulating substance, lepidimoide, using Arabidopsis thaliana.
1. We analyzed lepidimoide-like substance (LM) by means of HPLC and TLC, and clarified that almost organs (seeds, rosette leaves, stems, roots, inflorescences and immature fruits) of growing plants of A.thaliana, and the seeds of Capsella Bursa-pastris included LM.
2. We made clear that LM showed the two-faced activity in A.thaliana, i. e. promotion of hypocotyl elongation, cotyledon growth and cotyledon-petiole elongation, but inhibition of root elongation. LM reduced the growth of rosette leaves, plant heights, fresh weights of plants, pod number, yield of seeds. However, LM hastened flowering without decreasing number of rosette leaves suggesting LM accelerates the development of leaves within a shorter period. This effect of LM hastens the life cycle of plants.
3. We made a search for sensitive lines of A.thallana from a large number of ecotypes in "The Sendai Arabidopsis Seed Stock Center", and selected 2 lines (Aa-0, Bur-0), hypocotyl elongation and cotyledon growth of which were markedlypromoted.
4. The cells of seed coat of Brassicaceae have a differential structure, central elevation, from which LM seemed to be secreted. Therefore, we investigated the morphosis of the central elevations of newly related Brassica species. We recognized that all the plants (10 species) observed have the central elevation which secreted mucilage. However, the seeds of a mutant lacking the central elevation also secreted LM at about half amount of that in wild types.
5. We treated LM to the seedlings of various herbaceous plants, and recognized various opposite effects according to plant species and growth conditions.
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