The Effects of Benzyladenine, Cycloheximide, and Cordycepin on Wilting-Induced Abscisic Acid and Proline Accumulations and Abscisic Acid- and Salt-Induced Proline Accumulation in Barley Leaves

Abstract

Benzyladenine inhibits proline accumulation in wilted, abscisic acid (ABA)-treated, and salt-shocked barley leaves. It does not affect ABA accumulation or disappearance in wilted leaves. Inhibition of proline accumulation in salt-shocked leaves was observed both when benzyladenine was added at the beginning ofor after salt treatment. Cycloheximide (CHX) and cordycepin inhibited both ABA and proline accumulations in wilted barley leaves and proline accumulation in ABA-treated leaves. In salt-shocked leaves, cordycepin inhibited proline accumulation when added after salt treatment but before proline began to accumulate but not when added after the onset of proline accumulation. CHX delayed the accumulation of proline in salt-shocked leaves but, after a period of time, proline accumulated in the CHX-treated leaves at rates comparable to the salt-treated control. This delay and subsequent accumulation was observed when CHX was added before, during, and after salt treatment. However, the earlier in the salt treatment period that CHX was given, the longer was the observed delay. These results are interpreted to indicate that gene activation is involved in proline accumulation in response to wilting, to ABA, and to salt in barley leaves. This gene activation is in addition to the gene activation that is required for ABA accumulation in wilted leaves. If ABA accumulation is required for proline accumulation in wilted barley leaves, then two sets of gene activation are involved in wilting-induced proline accumulation. All of our results are consistent with this possibility but do not prove it. The inhibition of proline accumulation by benzyladenine is probably neither due to an effect on gene activation nor to an effect on the ABA level.

Involvement of Cl− in the Increase in Proline Induced by ABA and Stimulated by Potassium Chloride in Barley Leaf Segments

“…D-Mannose and the ionophore monensin, whose effects are under investigation in our laboratory, are known in many cases to inhibit the protein glycosilation or the movement of vesicles of the Golgi complex respectively (2,10), when used at the concentrations employed here. If these are their mechanisms of action, the inhibiting effect on proline increase is in agreement with they hypothesis of an involvement of a proteic factor in the proline accumulation induced by ABA (3,9). The data of Figure 4 show that, in the presence of all these substances, the Cl1- tions can be made about the reversing effect of Cl1-excess.…”

Euglena gracilis(Euglenophyceae) produces abscisic acid and cytokinins and responds to their exogenous application singly and in combination with other growth regulators

“…Furthermore, tests of 64 algal species revealed an accumulation of ABA under adverse environmental conditions (Hirsch et al, 1989). Similar effects are seen in bacteria (Cohen et al, 2008) and higher plants; ABA accumulates in the tissues of plants grown under water-, osmotic-or salt-stress conditions, and can act as an important stress-alleviating factor (Creelman & Zeevaart, 1985;LaRosa et al, 1985;Stewart et al, 1986;Bensen et al, 1988;Zeevaart & Creelman, 1988).…”

Effects of Cycloheximide on Abscisic Acid Biosynthesis and Stomatal Aperture in Bean Leaves

“…This increase is due to an increased rate of ABA biosynthesis (5,12) and can be blocked by inhibitors of cytoplasmic protein synthesis such as CH3 and puromycin (2,7,8), as well as inhibitors of transcription such as actinomycin D and cordycepin (2,8). Boggess and Stewart (1) reported that CH caused sunflower leaves to wilt, and Quarrie and Lister (7) reported a similar response in wheat leaves after a few hours of treatment.…”