Stress‐induced abscisic acid transients and stimulus‐response‐coupling

Abstract

1997, Stress-mduced abicisic acid transients and siimulus-response-coupling. -Physiol. Pianl. !(X): 491^99,Loss of cell turgttr and distortion of the plasma membrane occur a.s a result of dehydration and precede tbe stress-induced bulk increase in concentration of tissue abscisic acid. The latter ha-, been correlated v.iih induction of stress-related gene expression. However, several different stresses may trigger the same coupling mechanism. Thus, al least ibree signalling pathways have been proposed: abscisic acid-requiring, abscisic acid-responsive, and mechanosensors. In this paper, the role and contribution ol slress-induced ahscisic acid transients is examined in an attempi lo explain apparent abscisic acid-dependenl and -independeni stimulus-re.sponse-coupling. Early, intermediate, and late response stages are defined within the stress-induced abscisic acid transient and at leas! four signalling mechanisms are identified. These include, early and laie intracellular modulaiion of gene expression through derepression and/or negative regulation, rapid membrane-initialed calcium release and ion channel activation, and late tskm) ht}rmone-receptor induction of gene expression. An assessment of these proposed .ABA signalling mechanisms in lerms of .AB.A-dependem and -independent stimulus-response-coupling strongly suggests that rapid responses ma\ not be a prerequisite for slow responses and thai the receptor proteins involved have different stehc requiretments. i.e., they are tissue-and/or cell-specific,

Osmo-Sensitive and Stretch-Activated Calcium-Permeable Channels in Vicia faba Guard Cells Are Regulated by Actin Dynamics

“…These SA Ca 21 -permeable channels may, at least in part, account for the osmo-sensitive macroscopic Ca 21 currents across the PM of guard cells and serve as an osmotic-sensing target in a negative feedback loop. This negative feedback loop, together with the positive feedback loop proposed previously (Liu and Luan, 1998), may explain the mechanisms for osmo regulation of stomatal movements and oscillation (Cowan et al, 1997).…”

“…Therefore, SA Ca 21 channels may be also actively functioning during stomatal closure. The possible complex interaction between the positive and negative feedback mechanisms by which a number of ion transporters are regulated may explain stomatal oscillation under variable environmental conditions (Cowan et al, 1997). Liu and Luan (1998) reported that hypotonic or hypertonic condition caused gradual swelling or Figure 8.…”

Ethylene and nitric oxide are involved in maintaining ion homeostasis in Arabidopsis callus under salt stress

“…ABA could (Goh et al 1996;Zhang et al 2004). It is well known that ABA level increases when plants are stressed with NaCl (Cowan et al 1997;Barkla et al 1999). According to the above studies, the decrease in PM H + -ATPase activity by NaCl treatment might be caused by ABA production to reduce the protein phosphorylation.…”

Effects of senescence-induced alteration in cytokinin metabolism on source-sink relationships and ontogenic and stress-induced transitions in tobacco

“…4 show that there was no difference in the ability of wildtype and P SAG12 -IPT plants to accumulate ABA in response to a water-eficit stress. In both, ABA accumulation commenced 4 day after imposition of stress, reached a maximum within 10 day and then declined, presumably due to ABA-induced ABA catabolism (Cowan et al 1997). Typically, leaves from the apical and middle regions of the canopy produced more ABA than older basal leaves (Fig.…”