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Surrounding auxin maxima are cells with low auxin troughs, or auxin minima. For example, in the Arabidopsis fruit, auxin minima have been shown to be important for its tissue development. [28] Auxin has a significant effect on spatial and temporal gene expressions during the growth of apical meristems.
Polar auxin transport (PAT) is directional and active flow of auxin molecules through the plant tissues. The flow of auxin molecules through the neighboring cells is driven by carriers (type of membrane transport protein) in the cell-to-cell fashion (from one cell to other cell and then to the next one) and the direction of the flow is determined by the localization of the carriers on the ...
Most debates have concerned the signalling role of auxin and the molecular nature of cell wall modification. The current version holds that auxin activates small auxin-up RNA (SAUR) proteins, which in turn regulate protein phosphatases that modulate proton-pump activity. Acid growth is responsible for short-term (seconds to minutes) variation ...
Auxins activate proton pumps, decreasing the pH in the cells on the dark side of the plant. This acidification of the cell wall region activates enzymes known as expansins which disrupt hydrogen bonds in the cell wall structure, making the cell walls less rigid.
Auxins were the first class of growth regulators discovered. A Dutch Biologist Frits Warmolt Went first described auxins. [23] They affect cell elongation by altering cell wall plasticity. They stimulate cambium, a subtype of meristem cells, to divide, and in stems cause secondary xylem to differentiate.
In 1997 it was described how ARFs bind to auxin-response gene elements in promoters of auxin regulated genes, generally activating transcription of that gene when an Aux/IAA protein is not bound. [13] IAA inhibits the photorespiratory-dependent cell death in photorespiratory catalase mutants. This suggests a role for auxin signalling in stress ...
This modification is controlled by plant hormones like auxin. Auxin also controls the expression of some cell wall genes. [1] This form of growth does not involve an increase in cell number. During acid growth, plant cells enlarge rapidly because the cell walls are made more extensible by expansin, a pH-dependent
The plant hormone auxin binds Tir1 (Transport Inhibitor Response 1). Tir1 is an Auxin Signaling F-box Protein (AFB) that acts as an auxin receptor. Auxin-bound Tir1 stimulates binding of SCF-Tir1 to the AUX/IAA repressor. Subsequent degradation of the repressor results in activation of AUX/IAA (i.e. auxin-responsive) genes. [20]