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Auxin induces shoot apical dominance; the axillary buds are inhibited by auxin, as a high concentration of auxin directly stimulates ethylene synthesis in axillary buds, causing inhibition of their growth and potentiation of apical dominance. When the apex of the plant is removed, the inhibitory effect is removed and the growth of lateral buds ...
Plant hormones (or phytohormones) are signal molecules, produced within plants, that occur in extremely low concentrations. Plant hormones control all aspects of plant growth and development, including embryogenesis , [ 1 ] the regulation of organ size, pathogen defense, [ 2 ] [ 3 ] stress tolerance [ 4 ] [ 5 ] and reproductive development. [ 6 ]
Incoming light causes more auxin to flow from the exposed side to the shaded side, increasing the concentration of auxin on the shaded side and thus more growth occurring. [12] Fourth model. In the fourth model it shows the plant receiving light to inhibit auxin basipetal down to the exposed side, causing the auxin to only flow down the shaded ...
Phytohormones, particularly jasmonic acid (JA), ethylene, and auxin, are central regulators of the long-term developmental changes underpinning thigmomorphogenesis. Among these, JA is a primary mediator, modulating gene expression and enhancing stress tolerance in response to mechanical stimuli.
They are known to regulate axillary bud growth and apical dominance. According to the "direct inhibition hypothesis", these effects result from the ratio of cytokinin to auxin. [citation needed] This theory states that auxin from apical buds travels down shoots to inhibit axillary bud growth. This promotes shoot growth, and restricts lateral ...
The theory was widely accepted when first proposed, but began to receive serious criticism in the mid-1980s. [6] Arguments against the model have included views that growth regulators other than auxin may be involved, and that there is no difference in the concentration of auxin on the light and shady sides, or not enough difference to explain the difference in growth rates. [7]
Indole-3-acetic acid (IAA, 3-IAA) is the most common naturally occurring plant hormone of the auxin class. It is the best known of the auxins, and has been the subject of extensive studies by plant physiologists. [1] IAA is a derivative of indole, containing a carboxymethyl substituent. It is a colorless solid that is soluble in polar organic ...
Ethylene production can also be induced by a variety of external aspects such as mechanical wounding, environmental stresses, and certain chemicals including auxin and other regulators. [20] The pathway for ethylene biosynthesis is named the Yang cycle after the scientist Shang Fa Yang who made key contributions to elucidating this pathway.