Nyctinastenes - an Approach to New Phytohormones

A plant responds to an irritation by releasing irritants which may assist the organism endogenously in an intrinsic defence reaction. Only very small energy changes perceived by sensitive plants are sufficient to induce a series of physiological processes ultimately manifested as leaf movement. The chemonastic active compounds of sleeping and sensitive plants the Leaf MovementFactors Factors LMF are factors only in a stimulation chain that definitely also comprises amino acids and possibly even an inhibitor,D—pinitol. The active fraction from Acacia karroo characterized by the Fitting—Hesse-Schildknecht-test with the sensitive plant Mimosa pudica L. contains, besides the three Leaf Movement Factors K-LMF 1, 2 and 3, the Periodic Leaf Movement Factors K-PLMF 1 and 2. The assigned structure of these new phytohormones with the name Nyctinastenes" was confirmed by syntheses. The K-PLMF 1 is the 4-O—[3,5-Dihydroxybenzoic acid]13-D—glucosid-6 '-sulfate. DARWINIAN MOVEMENTS OF PLANTS A hundred years ago, in 188o, 'The Power of Movement in Plants" appeared as one of the later volumes of the collected works of Charles Darwin (Ref. 1). In his book, some 6oo pages long, Darwin described a fascinating behaviour pattern to which all rootlets, shoots, petioles, and leaf perform elliptical to circular motion. Why did Darwin begin at the age of 71 and not in the best of health 5 years before his death in 1882, a series of painstakingly planned experiments with about a dozen genera from completely different plant families on the circumnutation. His own discovery of the principle of evolution compelled him to do so, for according to this, it was impossible that the climbing plants should have developed into many groups if all plants did not possess some small capacity for movement. PLANT MIMICRY Sensitive plants were much discussed by philosophers, various theories being advanced to account for the rapid mimosa reaction. However only recently were investigators courageous enough to see a clear defence reaction in the fact that at the slightest touch the pairs of the pinnules folded together, first the pinnae and then the whole leaf pressing close to the rachis, and the whole plant pressing itself to the ground. The Mimosa plant becomes almost inconspicuous, exposing thorns on the stems. We agree with Hassenstein (Ref. 2) that this behaviour represents an excellent example of plant mimicry. NASTIC MOVEMENTS Movements, especially leaf movements, mostly fall into two categories: Rhythmic leaf movements in nyctinastic plants, and more rapid seismonastic movements, that occur in a limited number of nyctinastic species. Both movements were discussed already in the pre-Christian era, by Theophrast and Plinius T.E., Androsthenes, the admiral of Alexander the Great, described very early, 324/325 B.C., the plant sleep in the case of Tamarindus indica(Ref. 3). Analysis of leaf movements in the early eighteenth century provided the first clue that organisms have internal clocks (De Mairan 1729) (Ref. 4) — Zinn 1759) (Ref. 5) and subsequent studies from Pfeffer 1873 (Ref. 6) and Darwin 1881 (Ref. 1) are providing useful information of periodic nyctitropic movements of the pinnules of Leguminosae.