Auxin polar, inhibitors

Adventitious shoot formation occurred when the roots were cultured onto auxin-free medium as mentioned above. Since the decrease of auxin levels seemed to be important for the adventitious shoot formation, the influences of auxin inhibitors on shoot formation on the cultured root segments were investigated. The auxin polar transport inhibitor, 2,3,... 

The first study relates to the identification and design of novel herbicides and plant growth regulators that act by inhibiting polar transport of the plant hormone auxin (100). Previous studies (101) had identified seven auxin transport inhibitors, from which it was possible to describe a three-component... 

Powerful synthetic Polar Auxin Transport Inhibitors (PATIS) have been available for many years and have proved valuable investigative tools [35]. They... 

NPA and other synthetic auxin transport inhibitors can block PAT when they are incorporated into the receiver blocks in a classical donor-to-receiver polar transport assay. Figure 4 shows that quercetin in receiver blocks can inhibit lAA arrival, but only for the first 2 h of the transport test. Thereafter, the radioactivity delivered to the receiver blocks is increased compared to controls. In some experiments lAA (or NAA) arrival in quercetin-containing receiver blocks is increased at earlier times. A crossover is never observed when NPA is used. Quercetin and other flavonoids bind strongly to cellulose [31 ] and, unlike NPA, do not diffuse away... 

Katekar GF, Geissler AE (1977a) Auxin transport inhibitors II. 2-(l-Pyrenoyl)benzoic acid, a potent inhibitor of polar auxin transport. Aust J Plant Physiol 4 321-325 Katekar GF, Geissler AF (1977b) Auxin transport inhibitors III. Chemical requirements of a class of auxin transport inhibitors. Plant Physiol 60 826-829 Kato J (1958) Nonpolar transport of gibberellin through pea stem and a method for its determination. Science 128 1008-1009... 

Niedergang-Kamien E, Leopold AC (1957) Inhibitors of polar auxin transport. Physiol Plant 10 29-38... 

Thompson NP, Jacobs WP (1966) Polarity of lAA effect on sieve-tube and xylem regeneration in Coleus and tomato stems. Plant Physiol 41 673-682 Torrey JG (1953) The effect of certain metabolic inhibitors on vascular tissue differentiation in isolated pea roots. Am J Bot 40 525-533 Torrey JG, Loomis RS (1967) Auxin-cytokinin control of secondary vascular tissue formation in isolated roots of Raphanus. Am J Bot 54 1098-1106 Torrey JG, Fosket DE, Hepler PK (1971) Xylem formation A paradigm of cyto-differen-tiation in higher plants. Am Sci 59 338-352... 

The effects of ABA upon the wave-like pattern of the basipetal efflux of auxin were also observed when the inhibitor was applied for 100 min to the basal ends of tissue blocks (66 mm long). In these tests, however, suppression of the wave amplitudes was observed only at distances up to about 40 mm from the basal end to which ABA was applied (Fig. 7.2 B). This implies that the supracellular oscillatory system, in spite of its polarity, is capable of transmitting signals in both the basipetal and the acropetal direction. The velocity of signal transmission in the acropetal direction, however, appears to be slower. 

The results of experimental application of synthetic substances to stem tissue blocks showed that the oscillatory system involved in polar transport of auxin is sensitive both to growth stimulators and inhibitors, and that it reacts to them by modulation of at least the amplitude of the oscillations. Since the... 

The physical properties of pyridine-containing acids make them particularly attractive starting points for combinatorial libraries for herbicide screens. Pyridines are relatively polar (log P = 0.60 for pyridine vs. 2.13 for benzene) (4) and the sinq>le unsubstituted acids are weakly acidic (nicotinic acid pKa 4.8). (5) Perhaps for these reasons, pyridine-containing acids have found considerable utility as herbicides. Representative examples of commercially successful, phloem mobile, pyridine acids (or dieir derivatives) include picloram, clopyralid, and triclopyr (synthetic auxins) imazethapyr and nicosulfuron (ALS inhibitors) clodinafop and haloxyfop (ACCase inhibitors). Each has a direct counterpart in the conesponding benzene series but, in these instances, the pyridine analog is invariably the superior herbicide. 

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