Related Growth-Regulating Hormones

Chapter 24, Integration of Metabolism and Hormone Action, explains the organization strategies used to integrate metabolic processes in a multicellular organism. Like the first chapter in part 4, the content of chapter 24 relates to all of the chapters on metabolism (chapters 11-24). This chapter emphasizes the fact that hormones and closely related growth factors play a dominant role in regulating metabolic activities in different tissues. 

Different Activities of Several Brassinosteroids in Two Bean Internode Tests. It is a well-known phenomenon that structurally closely related plant growth regulators exhibit different orders of activity in different bioassays. This makes it difficult to define the criteria of specificity of their hormonal action. The same situation exists in the case of BRst, and it can be documented by the comparison of different BRst in the two bioassays. 

The first study relates to the identification and design of novel herbicides and plant growth regulators that act by inhibiting polar transport of the plant hormone auxin (100). Previous studies (101) had identified seven auxin transport inhibitors, from which it was possible to describe a three-component... 

C10H9N5O, Mr 215.21, mp. 267°C. K. belongs to the cytokinin group and is a derivative of adenine it occurs in various higher plants and yeasts and acts as a cell division factor. Like the closely related zeatin, K. is still active at million-fold dilutions and is thus considered to be a plant hormone. K. is isolated from autoclaved, aqueous slurries of deoxyribonucleic acids and is sometimes considered to be an artefact. K. is used as a plant growth regulator and also for inducing callus formation in plant cell cultures, etc.. ... 

A similar mode of action on the above photosynthetic parameter has been reported about another growth regulator-Jasmonic acid (JA) (10). To a certain extent the action of JA is similar to the inhibiting effect of ABA on the processes of germination and ageing, and also similar in the maner of effect on the stomata and on the protein hydrolysis (14, 17). In its chemical structure and methods of synthesis JA is very close to the group of the prostanoids which, in the case of animals are known to belong to the class of stress-related hormones (19). 

For the last two decades, in order to develop insecticides with selective toxicity, efforts to identify mimics (agonists) of 20-hydroxyecdysone, the insect molting hormone, have always led to the use of ecdysteroids or closely related steroidal analogs which are not commercially cost-effective. Recently, a new class of insect growth regulators, the 1,2-diacyl-l-alkylhydrazines, has been discovered and shown to be the first nonsteroidal agonists of 20-hydroxyecdysone. 

It has been demonstrated that 1,2-diacyl-l-alkylhydrazines represent a new class of selective insecticides in which RH-5849 and its structurally related analogs proved to be the first nonsteroidal mimics of 20-hydroxyecdysone insect molting hormone. Hopefully, by using this and other new insect growth regulators, we can gradually reduce our dependence on the conventional insecticides which have given us many problems related to the environmental impact. 

---