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η Carinae (Eta Carinae, abbreviated to η Car), formerly known as η Argus, is a stellar system containing at least two stars with a combined luminosity greater than five million times that of the Sun, located around 7,500 light-years (2,300 parsecs) distant in the constellation Carina.
It proposes that auxin, a plant growth hormone, is synthesized in the coleoptile tip, which senses light or gravity and will send the auxin down the appropriate side of the shoot. This causes asymmetric growth of one side of the plant. As a result, the plant shoot will begin to bend toward a light source or toward the surface. [citation needed]
Auxins (plural of auxin / ˈ ɔː k s ɪ n /) are a class of plant hormones (or plant-growth regulators) with some morphogen-like characteristics. Auxins play a cardinal role in coordination of many growth and behavioral processes in plant life cycles and are essential for plant body development.
AG Carinae, a massive Luminous blue variable and a part of the Carina constellation, which is transitioning from an O-type star to a Wolf-Rayet star. Eta Carinae, inside the Carina Nebula in the southern constellation of Carina. Eta Carinae is extremely massive, possibly as much as 120 to 150 times the mass of the Sun, and is four to five ...
The acid-growth hypothesis is a theory that explains the expansion dynamics of cells and organs in plants. It was originally proposed by Achim Hager and Robert Cleland in 1971. [1] [2] They hypothesized that the naturally occurring plant hormone, auxin (indole-3-acetic acid, IAA), induces H + proton extrusion into the apoplast.
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]
Lack of the plant hormone auxin can cause abnormal growth (right) 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 ...
However, the mechanism of auxin secretion is at the same time regulated by strigolactones, thus the latter can control secondary growth through auxin. [24] When applied in terminal buds of stem, strigolactone can block the expression of transport proteins required to move auxin across the buds, these proteins are denominated PIN1. [ 24 ]