Hormonal Modification of Plant Response to Water Stress

Section: Resultssupporting

confidence: 83%

The Role of Cytokinins in Chloroplast Lamellar Development

Alberte¹,

Naylor²

1975

“…Proposals have been made that cytokinins, in association with other hormones such as abscisic acid, may modify the response of plants to stressed conditions by altering stomatal opening and permeability of plant tissues to water (11,16,21 Table I. The kinetin-sprayed leaves had a lower stomatal resistance than did control leaves, while the turgor pressure of kinetin-sprayed leaves was lower than that of control leaves.…”

mentioning

confidence: 99%

Internal Water Status of Kinetin-treated, Salt-stressed Plants

Kirkham¹,

Gardner²,

Gerloff³

1974

“…Under drought, (1,4,11,12,17). In addition, many reports implicate ABA and cytokinins in the regulation of plant water balance (8,9,13 The first leaf of 10-day-old plants was used in the work on detached leaves. The leaves were placed on nylon frames fixed 5 cm above the floor of a darkened glass container, 20 X 20 X 60 cm, kept at room temperature.…”

mentioning

confidence: 99%

Leaf Water Content and Hormone Effects on Ribonuclease Activity

Arad¹,

Mizrahi²,

Richmond³

1973

In barley (Hordeum vulgare) leaves in which the water balance was not hampered, kinetin and abscisic acid effected the well documented decrease and increase, respectively, in RNase activity. When the plants were exposed to water shortage, leaf-water saturation deficit increased steadily, with kinetin enhancing and abscisic acid retarding the rise. Under drought, (1,4,11,12,17). In addition, many reports implicate ABA and cytokinins in the regulation of plant water balance (8,9,13 The first leaf of 10-day-old plants was used in the work on detached leaves. The leaves were placed on nylon frames fixed 5 cm above the floor of a darkened glass container, 20 X 20 X 60 cm, kept at room temperature. Ventilation was provided by keeping the glass cover 1 cm above the container. Humidity was simulated by spraying the leaves with water and placing the nylon frames over a 2-cm layer of water. In addition, the container was lined with moist filter paper. In the dry treatment, water was not added to the container nor applied to the leaves. In the whole plant, 0.1 mm kinetin and 0.4 mm ABA were applied by spraying every 3 days from germination until the end of the experiment. Detached leaves were soaked in either 50 ,pM kinetin or 40 ,uM ABA for 30 min. All the hormone solutions and the water controls contained 0.01% Tween-20.RNase activity in the leaves was determined after freezing the leaves in liquid nitrogen. They were then homogenized with 0.1 M phosphate buffer, pH 6.0, using a chilled pestle and mortar. The crude homogenate was filtered through Miracloth at 2 to 4 C and was used as the enzyme preparation. RNase activity was assayed by modification of the method of Tuve and Anfinsen (14): 1 ml of substrate solution (yeast RNA 4 mg/ml in 0.1 M phosphate buffer, pH 6.0) was placed in tubes; 0.25 ml of enzyme preparation and phosphate buffer was added to give a final volume of 2 ml.The assay mixture was incubated at 37 C for 1 hr. Undigested RNA was then precipitated with 0.5 ml of chilled 25% perchloric acid containing 0.75% uranyl-acetate. The