Plant hormones acid

Abscisin II is a plant hormone which accelerates (in interaction with other factors) the abscission of young fruit of cotton. It can accelerate leaf senescence and abscission, inhibit flowering, and induce dormancy. It has no activity as an auxin or a gibberellin but counteracts the action of these hormones. Abscisin II was isolated from the acid fraction of an acetone extract by chromatographic procedures guided by an abscission bioassay. Its structure was determined from elemental analysis, mass spectrum, and infrared, ultraviolet, and nuclear magnetic resonance spectra. Comparisons of these with relevant spectra of isophorone and sorbic acid derivatives confirmed that abscisin II is 3-methyl-5-(1-hydroxy-4-oxo-2, 6, 6-trimethyl-2-cyclohexen-l-yl)-c s, trans-2, 4-pen-tadienoic acid. This carbon skeleton is shown to be unique among the known sesquiterpenes. 

Maksimov I. V. Yarullina L. G. (2007) Salycilic acid and local resistance to pathogens / / Salycilic acid a plant hormone, Springer-Verlag. Berlin. Heidelberg. P. 323 - 334. 

The alcohol moiety is produced in a different manner from that of the acid moiety. The alcohol moiety resembles the plant hormone jasmonic acid (JA) (26) generated from linolenoyl moiety of lipids via (13,S )-hydroperoxy-linolenic acid (22), (12.13,S )-epoxylinolenic acid (23), and 12-oxo-cis-10.15-phytodienoic acid (24) by the oxylipin or octadecanoid pathway (Fig. 3) [31]. In fact, 13C was incorporated at pyrethrolone (1) carbon positions that agreed with those predicted to be labeled when the alcohol moiety is produced via the pathway (Fig. 3) [30]. Figure 3 illustrates that m-jasmone (25) is hydroxylated to yield jasmololone (4), which is then dehydrogenated to yield pyrethrolone (5). However, it has not yet been determined if this is actually the case. 

Fig. 3 Biosynthetic pathways to pyrethrins. The identified enzymes involved in biosynthesis are shown in orange. Note that green leaf volatiles and the plant hormone jasmonic acid share the oxylipin pathway. The phosphate moiety is indicated as P ...

It is important to keep in mind that any extraction of organic matter from soil will include both naturally occurring organic matter and organic contaminants. Separating the two at some later stage of analysis is thus an essential analytical step. For example, extraction of soil with hexane or dichloromethane will extract both l,l,l-trichloro-2,2-di(4-dicholorphenyl)ethane (DDT), a contaminant, and octadecanoic acid, a natural fatty acid. Also, the herbicide 2,4-dichlorophenoxy acetic acid, a contaminant, and indole-3-acetic acid, a natural plant hormone, are both extracted by water (see Figure 12.3). These... 

The ability of HRP to degrade the plant hormone indole-3-acetic acid (lAA) in the absence of hydrogen peroxide was noted as early as 1955 (136). Plant peroxidases are now known to be of major importance in the metabolism of lAA (137) (note that they are often referred to as indole acetic acid oxidases in the older literature). The mechanism of lAA oxidation by HRP C is complex and has been studied experimentally in great detail by several groups (23, 137). Reaction products include indole-3-methanol, indole-3-aldehyde, and 3-methylene oxin-dole, which is probably a nonenzymatic conversion product of indole-3-methylhydroperoxide. The most important developments in this area have been reviewed (23). 

Structural information on aromatic donor molecule binding was obtained initially by using H NMR relaxation measurements to give distances from the heme iron atom to protons of the bound molecule. For example, indole-3-propionic acid, a structural homologue of the plant hormone indole-3-acetic acid, was found to bind approximately 9-10 A from the heme iron atom and at a particular angle to the heme plane (234). The disadvantage of this method is that the orientation with respect to the polypeptide chain cannot be defined. Other donor molecules examined include 4-methylphenol (p-cresol) (235), 3-hydroxyphenol (resorcinol), 2-methoxy-4-methylphenol and benzhydroxamic acid (236), methyl 2-pyridyl sulfide and methylp-tolyl sulfide (237), and L-tyrosine and D-tyrosine (238). Distance constraints of between 8.4 and 12.0 A have been reported (235-238). Aromatic donor proton to heme iron distances of 6 A reported earlier for aminotriazole and 3-hydroxyphenol (resorcinol) are too short because of an inappropriate estimate of the molecular correlation time (239), a parameter required for the calculations. Distance information for a series of aromatic phenols and amines bound to Mn(III)-substituted HRP C has been published (240). 

Isoprenoids that have hormonal and signaling functions form an important group. These include steroid hormones (1 = 6) and retinoate (the anion of retinoic acid 1 = 3) in vertebrates, and juvenile hormone (1 =3) in arthropods. Some plant hormones also belong to the isoprenoids—e.g., the cytokinins, absci-sic acid, and brassinosteroids. 

NT581 Mousdale, D. M. A. Reversed-phase ion-pair high-performance liquid chromatography of the plant hormones indolyl-3-acetic, and abscisic acid. J Chromatogr 1981 209 489-493. 

DDT was not the only synthetic chemical to find a use in private and commercial gardens. Plant physiologists in the 1930s had accidentally discovered a way of selectively killing weeds in cereal crops (the dominant source of food for humans— wheat, barley, maize and rice). The plant physiologists interested in how plants controlled their growth had discovered a plant hormone—auxin (indole-3-acetic acid). Chemists soon found that, not only was it easy to make this compound, but they could also easily make... 

Formation of 2-AAP could be traced back to the plant hormone indole-3-acetic acid (lAA) [80], which is formed in the grape berry. The oxidative degra-... 

Plant hormones abscisic acid and gibberellic acid... 

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