Combined effects of hormones and light during growth promotion in primary leaves of Phaseolus vulgaris

1993 ◽  
Vol 71 (3) ◽  
pp. 501-505 ◽  
Author(s):  
Thomas G. Brock
Keyword(s):  
Cell Wall ◽  
Phaseolus Vulgaris ◽  
Gibberellic Acid ◽  
White Light ◽  
Osmotic Potential ◽  
Leaf Growth ◽  
Growth Potential ◽  
Combined Effects ◽  
Osmotic Concentration ◽  
Yield Threshold

Cell enlargement in primary leaves of bean is promoted by bright white light, gibberellic acid, or the cytokinin N6-benzyladenine. I examine the combined effects of light and hormones on growth, cell wall properties, and osmotic parameters during growth over 24 h. Applied alone, benzyladenine (10 μM), gibberellic acid (10 μM), and white light produced similar increases in the length and fresh weight of excised leaf strips over 24 h. The combined effects of hormones and light on growth were much less than additive. Individually, all three treatments significantly increased cell wall plastic extensibility over 24 h. However, benzyladenine combined with white light were additive in effect on plastic extensibility, and gibberellic acid combined with white light were synergistic. The differences in effects of hormones in white light on growth versus plastic extensibility indicate a decrease in growth potential, which is attributable in part to hormonal effects on osmotic concentration. Although white light alone increased osmotic concentration, both benzyladenine and gibberellic acid greatly decreased it, with or without white light. Furthermore, because growth potential is a function of both osmotic potential and wall yield threshold, it appears that yield threshold does not decline in parallel with osmotic potential in hormone-treated bean leaf strips. Finally, both benzyladenine and gibberellic acid inhibit the increase in osmotic solutes normally produced by white light. This effect, coupled with water uptake during cell expansion, would produce the observed decreases in osmotic concentration in hormone-treated strips. Hence, both benzyladenine and gibberellic acid interfere with light-induced growth, primarily through effects on the apparent ability of light to direct solute accumulation. Key words: Phaseolus vulgaris, leaf growth, cytokinin, gibberellic acid, light.

LIGHT-STIMULATED LEAF GROWTH ON INTACT AND EXCISED BEAN PLANTS (PHASEOLUS VULGARIS L.). II. EFFECT OF LIGHT DURATION AND TIMING OF APPLICATION

1999 ◽  
Vol 47 (3) ◽  
pp. 147-152
Author(s):  
Shimon Lavee ◽  
Elizabeth Van Volkenburgh ◽  
Robert E. Cleland
Keyword(s):  
Phaseolus Vulgaris ◽  
White Light ◽  
Leaf Growth ◽  
Relative Rate ◽  
Red Light ◽  
Leaf Expansion ◽  
Leaf Elongation ◽  
Leaf Unfolding ◽  
Light Duration ◽  
Partial Unfolding

The dependence of bean (Phaseolus vulgaris L. cv. Contender) leaf unfolding and expansion on light has been explored in intact and excised plants by varying the duration and timing of exposure to white light. Plants were grown for 10 days in dim red light (RL), and then some were excised. Both the intact and the excised plants were then exposed to varying white light (WL) treatments. In continuous WL, leaf unfolding began after 8 h, and was maximal after 36 h. For plants exposed to short WL treatments, as little as 2 h WL elicited partial unfolding when leaves were returned to RL and measured after 60 h. The relative rate of leaf elongation was most rapid during the first 2 h of WL and it rapidly decreased during the following 6–8 h. An 8 h exposure to WL followed by 52 h RL produced only a slightly lower leaf expansion than continuous WL for 32 h. Leaf elongation after 24 h constant WL irradiance was no longer light-dependent. The response of leaves on excised plants to WL was progressively less if treatment was delayed for 24 h after excision. In contrast, leaves on intact plants did not lose their ability to respond to light even after 48 h in the dark. The ability of leaves on intact or excised plants to elongate in RL decayed rapidly after day 10. These results indicate that light-stimulated leaf expansion in beans is mediated by some factors whose transport to the leaves is influenced by the presence of roots.

Analysis of cell wall hardening and cell wall enzymes of salt-stressed maize (Zea mays) leaves

2001 ◽  
Vol 28 (2) ◽  
pp. 101 ◽  
Author(s):  
Grant R. Cramer ◽  
Connie L. Schmidt ◽  
Chad Bidart
Keyword(s):  
Cell Wall ◽  
Zea Mays ◽  
Cell Walls ◽  
Leaf Growth ◽  
Physical Property ◽  
Physical Structure ◽  
In Vitro Assays ◽  
Xyloglucan Endotransglycosylase ◽  
Yield Threshold

It has been indicated that salinity inhibits maize (Zea mays L.) leaf growth and leaf cell expansion by increasing the apparent yield threshold of the cell wall. We tested whether this increase in the apparent yield threshold was a physical property of cell walls, using in vitro creep-type assays. Salinity had no significant effects on cell wall structural properties based upon several different in vitro assays. In support of these results, there were no differences between control and salt-stressed plants in their total apoplastic concentration of cell wall proteins, in the activity of apoplastic peroxidases or xyloglucan endotransglycosylase. We conclude that short-term salinity does not appear to inhibit maize leaf elongation by hardening the physical structure of the cell walls of the growing zone.

The expansin EXP1 gene in the elongation zone is induced during soybean embryonic axis germination and differentially expressed in response to ABA and PEG treatments

2020 ◽  
pp. 1-9
Author(s):  
Nidia H. Montechiarini ◽  
Luciana Delgado ◽  
Eligio N. Morandi ◽  
Néstor J. Carrillo ◽  
Carlos O. Gosparini
Keyword(s):  
Cell Wall ◽  
Seed Germination ◽  
Water Availability ◽  
Expression Profiles ◽  
Soybean Seed ◽  
Embryonic Axis ◽  
Growth Potential ◽  
Elongation Zone ◽  
Degenerate Primers ◽  
Embryonic Axes

Abstract During soybean seed germination, the expansive growth potential of the embryonic axes is driven by water uptake while cell wall loosening occurs in cells from the elongation zone (EZ). Expansins are regarded as primary promoters of cell wall remodelling in all plant expansion processes, with the expression profiles of the soybean expansins supporting their cell or tissue specificity. Therefore, we used embryonic axes isolated from whole seed and focused on the EZ to study seed germination. Using a suite of degenerate primers, we amplified an abundantly expressed expansin gene at the EZ during soybean embryonic axis germination, which was identified as EXP1 by in silico analyses. Expression studies showed that EXP1 was induced under germination conditions in distilled water and down-regulated by abscisic acid (ABA), which inhibits soybean germination by physiologically restraining expansion. Moreover, we also identified a time window of ABA responsiveness within the first 6 h of incubation in water, after which ABA lost control of both EXP1 expression and embryonic axis germination, thus confirming the early role of EXP1 in the EZ during this process. By contrast, EXP1 levels in the EZ increased even when germination was impaired by osmotically limiting the water availability required to develop the embryonic axes’ growth potential. We propose that these higher EXP1 levels are involved in the fast germination of soybean embryonic axes as soon as water availability is re-established. Taken together, our results show strong EXP1 expression in the EZ and postulate EXP1 as a target candidate for soybean seed germination control.

scholarly journals Regulation of Cell Wall Synthesis in Avena Stem Segments by Gibberellic Acid

1975 ◽  
Vol 55 (6) ◽  
pp. 1043-1047 ◽  
Author(s):  
Michael J. Montague ◽  
Hiroshi Ikuma
Keyword(s):  
Cell Wall ◽  
Gibberellic Acid ◽  
Cell Wall Synthesis ◽  
Stem Segments

Microtubular configurations during endosperm development in Phaseolus vulgaris

1994 ◽  
Vol 72 (10) ◽  
pp. 1489-1495 ◽  
Author(s):  
X. XuHan ◽  
A. A. M. Van Lammeren
Keyword(s):  
Electron Microscopy ◽  
Cell Wall ◽  
Phaseolus Vulgaris ◽  
Key Words ◽  
Cell Walls ◽  
Endosperm Development ◽  
Initial Cell ◽  
Related Cell ◽  
Cellular Endosperm ◽  
Cell Shaping

Microtubular cytoskeletons in nuclear, alveolar, and cellular endosperm of bean (Phaseolus vulgaris) were analyzed immunocytochemically and by electron microscopy to reveal their function during cellularization. Nuclear endosperm showed a fine network of microtubules between the wide-spaced nuclei observed towards the chalazal pole. Near the embryo, where nuclei were densely packed, bundles of microtubules radiated from nuclei. They were formed just before alveolus formation and functioned in spacing nuclei and in forming internuclear, phragmoplast-like structures that gave rise to nonmitosis-related cell plates. During alveolus formation cell plates extended and fused with other newly formed walls, thus forming the walls of alveoli. Growing wall edges of cell plates exhibited arrays of microtubules perpendicular to the plane of the wall, initially. When two growing walls were about to fuse, microtubules of both walls interacted, and because of the interaction of microtubules, the cell walls changed their position. When a growing wall was about to fuse with an already existing wall, such interactions between microtubules were not observed. It is therefore concluded that interactions of microtubules of fusing walls influence shape and position of walls. Thus microtubules control the dynamics of cell wall positioning and initial cell shaping. Key words: cell wall, cellularization, endosperm, microtubule, Phaseolus vulgaris.

scholarly journals Effect of NaCl on seed germination in some Centaurium Hill. Species (Gentianaceae)

2007 ◽  
Vol 59 (3) ◽  
pp. 227-231 ◽  
Author(s):  
S. Zivkovic ◽  
M. Devic ◽  
B. Filipovic ◽  
Z. Giba ◽  
D. Grubisic
Keyword(s):  
Life History ◽  
Salt Tolerance ◽  
Seed Germination ◽  
Gibberellic Acid ◽  
White Light ◽  
The Other ◽  
Distilled Water ◽  
Nacl Concentration ◽  
History Of ◽  
Species Specific

The influence of high NaCl concentrations on seed germination in both light and darkness was examined in the species Centaurium pulchellum, C. erythraea, C. littorale, C. spicatum, and C. tenuiflorum. Salt tolerance was found to depend on the life history of the seeds. To be specific, seeds of all five species failed to complete germination when exposed to continuous white light if kept all the time in the presence of 100-200 mM and greater NaCl concentrations. However, when after two weeks NaCl was rinsed from the seeds and the seeds were left in distilled water under white light for an additional two weeks, all species completed germination to a certain extent. The percent of germination not only depended on NaCl concentration in the prior medium, but was also species specific. Thus, seeds of C. pulchellum, C. erythraea, and C. littorale completed germination well almost irrespective of the salt concentration previously experienced. On the other hand, seeds of C. tenuiflorum completed germination poorly if NaCl concentrations in the prior media were greater than 200 mM. When seeds after washing were transferred to darkness for an additional 14 days, they failed to complete germination if previously imbibed on media containing NaCl concentrations greater than 400 mM. However, the seeds of all species, even if previously imbibed at 800 mM NaCl, could be induced to complete germination in darkness by 1 mM gibberellic acid. .

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