A Leaf Elongation Assay Detects an Unknown Growth Inhibitor in Xylem Sap From Wheat and Barley

1992 ◽  
Vol 19 (2) ◽  
pp. 127 ◽  
Author(s):  
R Munns
Keyword(s):  
Abscisic Acid ◽  
Growth Regulators ◽  
Saline Soil ◽  
Xylem Sap ◽  
Growth Inhibitor ◽  
Leaf Expansion ◽  
Growth Promoter ◽  
Inhibitory Substance ◽  
Leaf Elongation ◽  
Transpiration Stream

Recent research suggests that chemicals sent from roots in the transpiration stream could control leaf expansion, and that xylem sap from plants in dry or saline soil could contain increased amounts of a growth inhibitor, or decreased amounts of a growth promoter. In order to test these possibilities, a bioassay that could detect the presence of growth regulators in xylem sap was developed using whole shoots of wheat and barley seedlings. The bioassay showed that xylem sap collected from intact, transpiring plants in a drying soil contained a strong growth inhibitor. The inhibitory substance was not abscisic acid: while the concentration of abscisic acid in the sap rose as the soil dried, the highest concentration found, 4 × 10-8 M, was too low to inhibit leaf expansion. The identity of the new inhibitor is unknown.

Involvement of Abscisic Acid in Controlling Plant Growth in Soil of Low Water Potential

1993 ◽  
Vol 20 (5) ◽  
pp. 425 ◽  
Author(s):  
R Munns ◽  
RE Sharp
Keyword(s):  
Abscisic Acid ◽  
Plant Growth ◽  
Water Potential ◽  
Cell Expansion ◽  
Shoot Growth ◽  
Xylem Sap ◽  
Leaf Expansion ◽  
Root And Shoot Growth ◽  
Dry Soil

Hormones appear to be important in controlling plant growth in soils of low water potential, particularly in changing the root:shoot ratio as the soil dries or becomes saline, and in communicating soil conditions to the leaves. This review has necessarily focused on abscisic acid (ABA), as there is little information about the role of other hormones in controlling growth in dry or saline soils. ABA is partly responsible for the differential response of root and shoot growth to dry soils. In dry soil it maintains root growth and inhibits shoot growth. However, when applied to well-watered plants, it usually inhibits root and shoot growth, showing that plants in dry soil respond quite differently from well-watered plants. ABA affects the rate of cell expansion in plants in dry soils: it maintains cell expansion in roots and inhibits that in leaves. It may also affect the rate of cell production, but little is known about this. The role of ABA as a long-distance signal in controlling growth by root-to-shoot communication is unclear: the concentrations found in xylem sap can affect stomatal conductance, but seem too low to affect leaf expansion. Yet drought and salinity generally affect leaf expansion before they affect leaf conductance. A possible solution to this puzzle is that ABA is transported in xylem sap in a complexed form, or that another compound in xylem sap stimulates the synthesis or activity of ABA in leaves, or affects leaf expansion independently of ABA.

Effect of Growth Regulators on Stomatal Structure and Development in the Cotyledons of Lagenaria leucantha (Duch.) Rusby

1975 ◽  
Vol 23 (1) ◽  
pp. 13 ◽  
Author(s):  
JA Inamdar ◽  
M Gangadhara
Keyword(s):  
Growth Regulators ◽  
Growth Inhibitor ◽  
Guard Cells ◽  
Inhibitory Effect ◽  
Subsidiary Cell ◽  
Growth Promoter ◽  
Stomatal Index ◽  
Stomatal Frequency ◽  
Growth Promoters ◽  
High Concentration

In untreated cotyledons (controls) anomocytic stomata and stomata with a single subsidiary cell were observed. In cotyledons treated with growth regulators, anisocytic, paracytic, cyclocytic and several abnormal stomatal types were observed in addition to those found in the controls. Gibberellic acid, though a growth promoter, acted as an inhibitor at high concentration. Ascorbic acid at 25 p.p.m. increased the stomatal index and the size of guard cells, while the stomatal frequency decreased. Sucrose at 2000 p.p.m. increased the stomatal index and the length of guard cells. 2,3,5-Tri-iodobenzoic acid caused degeneration of guard cells and acted as a growth inhibitor at higher concentrations. As the concentration of kinetin increased, decreases in the stomatal frequency, index and size of guard cells were noted. Kinetin also induced the formation of contiguous stomata and the division of guard cells. Sulphanilamide could act either as an inhibitor or as a promoter as its concentration increased. Coumarin at 50 p.p.m. reduced the size of guard cells and the stomatal frequency, and commonly induced persistent stomatal initials, while at 100 p.p.m. only the radicle emerged and the cotyledons failed to emerge from the seed-coat. Increased concentrations of colchicine promoted more induction of persistent stomatal initials, and inhibited stomatal formation as was evidenced by a reduced stomatal frequency and index. Colchicine at 50 p.p.m. induced formation of double pores in a stoma, abnormally large pore sizes, and increases in the size of guard cells and their nuclei. With maleic hydrazide the sizes of guard and epidermal cells were reduced and persistent stomatal initials occasionally formed. Growth promoters could sometimes interact with inhibitors to overcome their inhibitory effect, depending on the substances used in combination and their concentrations.

scholarly journals Abscisic acid-inducible 25 kDa xylem sap protein abundant in winter poplar

Plant Root ◽  
2011 ◽  
Vol 5 ◽  
pp. 63-68 ◽  
Author(s):  
Jun Furukawa ◽  
Yuta Abe ◽  
Hiroaki Mizuno ◽  
Kaoru Matsuki ◽  
Keiko Sagawa ◽  
...  
Keyword(s):  
Abscisic Acid ◽  
Xylem Sap

The Xylem Sap of Maize Roots: Its Collection, Composition and Formation

1988 ◽  
Vol 15 (4) ◽  
pp. 557 ◽  
Author(s):  
MJ Canny ◽  
ME Mccully
Keyword(s):  
Amino Acids ◽  
Organic Acids ◽  
Organic Acid ◽  
Aspartic Acid ◽  
Xylem Sap ◽  
Great Variability ◽  
Reduced Pressure ◽  
Transpiration Stream ◽  
Maize Roots ◽  
Total Amino Acids

Three methods of sampling xylem sap of maize roots were compared: sap bleeding from the stem cut just above the ground; sap bleeding from the cut tops of roots still undisturbed in the ground; and sap aspirated from excavated roots under reduced pressure. The bleeding saps were often unobtainable. When their composition was measured with time from cutting, the concentrations of the major solutes approximately doubled in 2 h. Aspirated sap was chosen as the most reliable sample of root xylem contents. Solute concentrations of the saps showed great variability between individual roots for all solutes, but on average the concentrations found (in �mol g-1 sap) were: total amino acids, 1.8; nitrate, 1.8; sugars (mainly sucrose), 5.4; total organic acids, 18.3. Individual amino acids also varied greatly between roots. Glutamine, aspartic acid and serine were generally most abundant. The principal organic acid found was malic, approximately 8 �mol g-1. From these analyses the ratios of carbon in the fractions (sugars : amino acids : organic acids) = (44 : 6 : 50). 14Carbon pulse fed to a leaf appeared in the root sap within 30 min, rose to a peak at 4-6 h, and declined slowly over a week. During all this time the neutral, cation and anion fractions were sensibly constant in the proportions 86 : 10 : 4. The 14C therefore did not move towards the equilibrium of 12C-compounds in the sap. It is argued that the results do not support a hypothesis of formation of amino carbon from recent assimilate and reduced nitrate in the roots and an export of this to the shoot in the transpiration stream.

Effect of Plant Growth Regulators on Growth and Quality Flower Production of Chrysanthemum (Chrysanthemum Indicum L.)

2022 ◽  
Vol 2 (1) ◽  
pp. 10-18
Author(s):  
Md Ehsanullah ◽  
Ahasan Ullah Khan ◽  
Md Kamruzzam ◽  
Sarah Tasnim
Keyword(s):  
Plant Growth ◽  
Plant Growth Regulators ◽  
Growth Regulators ◽  
Block Design ◽  
Research Centre ◽  
Vase Life ◽  
Flower Initiation ◽  
Growth Promoter ◽  
Flower Production ◽  
Minimum Number

A field study was conceded to assess the effect of plant growth regulators on growth and quality flower production of chrysanthemum at Horticulture Research Centre (HRC), Gazipur, Bangladesh. The experiment was laid out in Randomized Complete Block Design (RCBD) with ten (10) treatments and three replications. The treatments of plant growth regulators concentration were T1-50 ppm GA3, T2-100 ppm GA3, T3-150 ppm GA3, T4-400 ppm CCC, T5-600 ppm CCC, T6-800 ppm CCC, T7-250 ppm MH, T8-500 ppm MH, T9-750 ppm MH and, T10-Control. The maximum spreading of plant (27.0 cm) was observed when plants were treated with GA3 @ 150 ppm where the minimum plant spread (16.8 cm) was recorded in plants treated with CCC @ 800 ppm. The higher number of suckers (33) per pot was produced when pots were treated with GA3 @ 150 ppm whereas, application of CCC at three different concentrations produced lower number of suckers.  The highest number of flower (40) was recorded with 150 ppm GA3, where minimum number of flowers (25) per pot in 800 ppm CCC. The plants sprayed with 50 ppm GA3 took 48 days to flower initiation, whereas, it took 70 days with 750 ppm MH. the highest plants recorded (7.40 cm) with 800 ppm CCC, whereas, lowest size (6.50 cm) was obtained with the application of 500 ppm MH. The maximum vase life of flowers was recorded for the treatment 800 ppm CCC (15 days), which was at par with 13 days vase life obtained by spraying 600 ppm CCC. Therefore, it is concluded that the GA3 acted as growth promoter and the CCC acted as growth retardants on yield and quality of chrysanthemum.

The role of exogenous plant regulators in the dormancy of onion bulbs

1974 ◽  
Vol 82 (1) ◽  
pp. 113-116 ◽  
Author(s):  
M. Abdel-Rahman ◽  
F. M. R. Isenberg
Keyword(s):  
Abscisic Acid ◽  
Growth Regulators ◽  
Maleic Hydrazide ◽  
Rest Period ◽  
Storage Period ◽  
Inhibitory Effect ◽  
Onion Bulbs ◽  
Subsequent Application

SUMMARYExperiments were conducted to study the effect of plant injection with growth regulators on the dormancy of onion bulbs cv. Elba Globe. Application of abscisic acid induced early senescence of the leaves and prolonged the rest period of the bulbs. This effect was partially overcome by subsequent applications of gibberellin, auxin or cytokinin and totally overcome with the application of a mixture of the three hormones. Maleic hydrazide application prolonged the rest period by inhibiting both sprouting and rooting of the bulbs throughout the storage period. This inhibitory effect was not overcome by the subsequent application of auxin, gibberellin, kinetin, or their combinations. Ethephon application increased rooting of bulbs and partially overcame the effect of abscisic acid on dormancy.

scholarly journals Longevity of wild pansy flowers treated with growth regulators

2018 ◽  
Vol 24 (2) ◽  
pp. 103-108
Author(s):  
Tania Pires Da Silva ◽  
Fernanda Ferreira Araujo ◽  
Fernando Luiz Finger
Keyword(s):  
Weight Loss ◽  
Abscisic Acid ◽  
Growth Regulators ◽  
Water Status ◽  
Fluorescent Light ◽  
Distilled Water ◽  
Fresh Weight ◽  
Exogenous Ethylene ◽  
Fourth Experiment ◽  
And Control

The objective of this study was to evaluate the growth regulators action on the senescence of wild pansy flowers. In the first experiment, floral stems were treated with ethylene for 24 hours at concentrations of 0.1, 1.0, 10, 100 and 1000 μL L-1 and control without the hormone. In a second experiment, the flowers were immersed in solutions of abscisic acid (ABA) containing 5, 20, 50 and 100 μM for one minute and control with water. In a third experiment, 1-methylcyclopropene (1-MCP) was applied at concentrations of 0.5, 1.0 and 1.5 μL L-1 and control without the chemical. In a fourth experiment, 1-MCP and ethylene were applied, where 1-MCP was first applied followed by ethylene. After the treatments with 1-MCP and ethylene, the floral stems were removed from the hermetic chambers and kept in a vessel containing distilled water at 25 °C, 10 μmol m-2 s- 1 white fluorescent light and 50-70% relative humidity as for the ABA treatment. Flowers treated with ethylene did not present significant differences among the concentrations for visual senescence, showing evidence that this flower is not sensitive to ethylene. Treatment with 1000 μL L-1 of ethylene led to a slightly higher fresh weight loss than other treatments, which had a loss of about 33% at end of the experiment. For the ABA treatment, the flowers showed similar fresh weight loss among the different treatments; however, higher concentrations induced slight senescence of flowers. The use of 1-MCP increased the longevity of wild pansy flowers. These results show that 1-MCP is beneficial in maintaining the flower water status, even in the presence of exogenous ethylene, although ethylene may not be directly involved in the senescence of wild pansy flowers.

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.

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