Ethylene physiological responses

Bell CL, Peppas NA. Water, solute and protein diffusion in physiologically responsive hydrogels of poly(methacrylic acid-g-ethylene glycol). Biomaterials 1996, 17, 1203-1218. 

Physiological Responses to Ethylene. Classically, two types of fruit have been recognized with respect to their response to ethylene (1) (a) climacteric fruit, such as apples... 

Ethylene coordinates the expression of genes responsible for enhanced respiratory metabolism, chlorophyll degradation, carotenoid synthesis, conversion of starch to sugars, increased activity of cell wall-degrading enzymes, aroma volatile production, and so on. All these events stimulate a series of biochemical, physiological, and structural changes making fruits mature and attractive to the consumer. 

The production of ethylene in fruit tissue and in small amounts in leaves may justify its consideration as a hormone, functioning in the gaseous state, Cherimoyas and some varieties of pear produce 1000 times the effective physiological concentration. Ethylene formation is closely linked to oxidation and may be centered in the mitochondria. Its effects are to promote cell-wall softening, starch hydrolysis, and organic add disappearance in fruits—the syndrome known as ripening. Ethylene also decreases the geotiopic responses of stems and petioles. 

Several other thermally responsive systems can be cited, such as poly- or oligo(ethylene glycol) methacrylate (OEGMA) derivatives [33 13], We recently showed that copolymers of 2-(2-methoxyethoxy)ethyl methacrylate (MEO2MA) and OEGMA exhibited a LCST in water that can be adjusted to physiological... 

The three experiments with brassinolide showed that the physiological effect of brassinolide seems to be that of both an auxin and cytokinin. The twining growth effect, however, is the characteristic response evoked by brassi-nosteroids, and it was thought that the twining movement of the tendril and the twiner (climber) reported for auxin, or abscisic acid (ABA), or ethylene earlier is doubtful. In other words, brassinolide as a steroid may act on membrane systems. 

Until the discovery of brassinolide by USDA scientists in 1979, it was thought that only five groups (indole auxins, gibberellins, cytokinins, abscisic acid, and ethylene) of hormones were responsible for regulating plant growth and development. Following this discovery, a number of compounds similar to brassinolide both in structure and physiological activity were isolated from different parts of plants. On the basis of published... 

---