scholarly journals Rapid Initiation of Thymidine Incorporation into Deoxyribonucleic Acid in Vegetative Tobacco Stem Segments Treated with Indole-3-acetic Acid

1975 ◽  
Vol 56 (2) ◽  
pp. 171-176 ◽  
Author(s):  
William L. Wardell
2012 ◽  
Vol 20 (1) ◽  
pp. 97-114 ◽  
Author(s):  
Elżbieta Węgrzynowicz-Lesiak ◽  
Marian Saniewski ◽  
Justyna Góraj ◽  
Marcin Horbowicz ◽  
Kensuke Miyamoto ◽  
...  

ABSTRACT The purpose of this study was to clarify the effect of sucrose on auxin-induced growth of stem excised from growing tulips and excised directly from cooled and not cooled bulbs, and on the growth of excised IV internode from growing plants in the presence of auxin. In all cases flower bud was replaced by IAA (indole-3- acetic acid, 0.1%, w/w in lanolin) and basal part of excised segments of stem was kept in distilled water or in solution of various sugars at different concentrations. IAA-induced growth of excised stems isolated from growing tulips was inhibited by sucrose at concentrations of 5.0% and 10.0%, but sucrose at 1.25% and 2.5% did not. Sucrose at all concentrations used evidently delayed senescence and increased chlorophyll contents in excised stems in the presence of IAA. Sucrose induced stiffing in isolated stems in the presence of IAA, and much less infective by pathogen in comparison to stem treated with IAA only. Mannitol and sorbitol at concentrations of 5.0% and 10.0% substantially inhibited IAA-induced growth of stem segments. Stem segments excised from cooled and not cooled tulip bulbs were more sensitive than those isolated from growing shoots due to application of sucrose and glucose; more inhibitory effect was observed. Sucrose at concentrations of 5.0% and 10.0% only slightly inhibited growth of IV internode treated with IAA and all concentrations of sucrose (1.25%, 2.5%, 5.0% and 10.0%) substantially increased chlorophyll content. The possible mode of actions of sucrose interacting with auxin to regulate stem growth is also discussed although sugar response is complicated by the fact that plants have multiple sugar-response pathways.


2014 ◽  
Vol 60 (1-2) ◽  
pp. 51-66
Author(s):  
Jacek A. Adamczyk

The acropetal effects of auxin on elongation of axillary buds and on modulation of the wave-like pattern of basipetal efflux of natural auxin to agar from <i>Acer pseudoplatanus</i> L. shoots were studied. When synthetic IAA was applied to cut surfaces of one of two branches the elongation growth of buds situated on the opposite branch was retarded, suggesting regulation independent of the direct action of the molecules of the applied IAA. Oscillations in basipetal transport of natural auxin along the stem segments were observed corroborating the results of other authors using different tree species. Apical application of synthetic IAA for 1 hour to the lateral branch caused a phase shift of the wave-like pattern of basipetal efflux of natural auxin, when the stem segment above the treated branch was sectioned. The same effect was observed evoked by the laterally growing branch which is interpreted as an effect of natural auxin produced by the actively growing shoot. These modulations could be propagated acropetally at a rate excluding direct action of auxin molecules at the sites of measurement. The results seem to corroborate the hypothesis suggesting that auxin is involved in acropetal regulation of shoot apex growth through its effect upon modulation of the vectorial field which arises when the auxin-waves translocate in cambium.


1978 ◽  
Vol 62 (5) ◽  
pp. 807-811 ◽  
Author(s):  
Edward N. Rapoport ◽  
Keith E. Heller ◽  
P. Dayanandan ◽  
Frederick V. Hebard ◽  
Peter B. Kaufman

1983 ◽  
Vol 10 (2) ◽  
pp. 131 ◽  
Author(s):  
DW Sheriff

The effect of indole-3-acetic acid (IAA) on stem radius growth, tracheid lumen diameter, and tracheid wall thickness in P. radiata was investigated. Stem segments from trees that normally produce high-density wood and from trees that normally produce low-density wood were grown in vitro at a number of IAA concentrations between 0 and 20 mg l-1. Maximum increase in stem radius and maximum tracheid lumen diameter were found at IAA concentrations of 6-10 mg l-1. Tracheid wall thickness increased approximately linearly as IAA concentration was increased up to 20 mg l-1. Absolute differences in radial stem increase and in cell lumen diameter between the high- and the low-density stems were greatest at IAA concentrations of 4-10 mg l-1. At low or high IAA concentrations, absolute differences between the clones in their stem radial increase and in their tracheid lumen diameter were small. Proportional differences between the clones in these two factors were greatest at IAA concentrations of 10 mg l-1. Clonal differences in the tracheid wall volume per unit stem volume could account for the differences in wood density only at IAA concentrations of 4-10 mg l-1.


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