" Regulation of ethylene biosynthesis [in plant tissues]. "

The chloroplast methylerythritol phosphate pathway is the primary source of the DMAPP used in cytokinin biosynthesis by plant IPT enzymes. This pathway occurs in plastids, which is where the majority of IPT enzymes are localized in plants. Thus, the primary site of cytokinin biosynthesis in plants is in the plastids. However, in Arabidopsis, at least one IPT protein, IPT3, can be modified by the addition of a farnesyl moiety (Galichet et al. 2008). Farnesylation is the addition of a hydrophobic farnesyl group (a long-chain lipid molecule made from isoprene subunits) to C-terminal cysteine(s) of the target protein, which can alter its subcellular localization, often targeting the protein to a membrane. The farnesylation of IPT3 directs it to the nucleus, rather than to the plastids, where the non-farnesylated IPT3 protein is localized. Furthermore, the IPT4 protein is found in the cytoplasm, and the IPT7 protein is found in mitochondria. Thus, the plastids are the primary sites of cytokinin biosynthesis, but not the only sites.

Kende H 1993 Ethylene biosynthesis.

Protein turnover plays a critical role in both ethylene biosynthesis and ethylene signalling.

The role of ACS turnover in regulating ethylene biosynthesis.

Hall BP, Qureshi SN and Schaller GE (2007) Ethylene receptors: ethylene perception and signal transduction. Journal of Plant Growth Regulation 26: 118–130.

Products marketed to reduce ethylene in your refrigerator

Gazzarrini S and McCourt P (2003) Cross‐talk in plant hormone signalling: what Arabidopsis mutants are telling us. Annals of Botany 91: 605–612.

The simple gas ethylene has been recognized as a plant hormone for almost a century ().

Regulation of Ethylene Biosynthesis | SpringerLink

The role of ACC became evident in experiments in which plants were treated with [14C]methionine. Under anaerobic conditions, ethylene was not produced from the [14C]methionine, and 14C-labeled ACC accumulated in the tissue. On exposure to oxygen, however, ethylene production surged. The labeled ACC was rapidly converted to ethylene in the presence of oxygen by various plant tissues, suggesting that ACC is the immediate precursor of ethylene in higher plants and that oxygen is required for the conversion.

Ethylene Biosynthesis | Annual Review of Plant Biology

English PJ, Lycett GW, Roberts JA, Jackson MB 1995 Increased 1-aminocyclopropane-1-carboxylic acid oxidase activity in shoots of flooded tomato plants raises ethylene production to physiologically active levels.

T1 - Regulation of ethylene biosynthesis in response to pollination in tomato flowers

Ethylene Biosynthesis and its Regulation in Higher …

Figure A3.9 The three stages of GA biosynthesis. In stage 1, geranylgeranyl diphosphate (GGPP) is converted to ent-kaurene. In stage 2, ent-kaurene is converted to GA12. In many plants, GA12 is converted to GA53 by hydroxylation at C-13. In stage 3 in the cytosol, GA12 or GA53 is converted, via parallel pathways, to other GAs. This conversion proceeds with a series of oxidations at C-20, resulting in the eventual loss of C-20 and the formation of C19-GAs. A 3β-hydroxylation reaction then produces GA4 and GA1 as the bioactive GAs in each pathway. In most plants the 13-hydroxylation pathway predominates, although in Arabidopsis and some other plants, the non-13-OH-pathway is the main pathway. OL, open lactone. See the table for full names and subcellular locations of the enzymes.

Mattoo AK and Suttle JC (1991) The Plant Hormone Ethylene. Boca Raton: CRC Press, Inc.

Biosynthesis and Action of Ethylene

In flooded tomato plants, the accumulated ACC is transported from the root to the shoot (via the xylem) where it is then rapidly oxidized to ethylene, inducing epinasty (Bradford and Yang, 1980; English et al, 1995) and adventitious root formation (Visser et al, 1996).

(1999) Factors regulating ethylene biosynthesis in etiolated Arabidopsis thaliana seedlings.

The Biosynthesis of Ethylene - UNC Chapel Hill

In general, when ACC is supplied exogenously to plant tissues, ethylene production increases substantially. This observation indicates that the synthesis of ACC is usually the biosynthetic step that limits ethylene production in plant tissues. Exceptions include tissues with high rates of ethylene synthesis, such as ripening fruits (see below).