Does abscisic acid influence proline accumulation in stressed leaves?

In silico characterisation and functional validation of chilling tolerant divergence 1 (COLD1) gene in monocots during abiotic stress

The G protein-coupled receptor is one of the major transmembrane proteins in plants. It consists of an α subunit, a β subunit and three γ subunits. Chilling tolerant divergence 1 (COLD1) includes a Golgi pH receptor (GPHR) domain, which maintains cell membrane organisation and dynamics, along with abscisic acid linked G protein-coupled receptor (ABA_GPCR) that regulates the signalling pathways during cold stress. In the present study, we performed characterisation of a homologous COLD1 from the economically important monocot species Oryza sativa L., Zea mays L., Sorghum bicolor (L.)Moench and Erianthus arundinaceus (L.) Beauv. IK 76-81, a wild relative of Saccharum. COLD1 was isolated from E. arundinaceus IK 76-81, analysed for its evolution, domain, membrane topology, followed by prediction of secondary, tertiary structures and functionally validated in all four different monocots. Gene expression studies of COLD1 revealed differential expression under heat, drought, salinity and cold stresses in selected monocots. This is the first study on regulation of native COLD1 during abiotic stress in monocots, which has opened up new leads for trait improvement strategies in this economically important crop species.

Anther culture in rice: IV. The effect of abscisic acid on plant regeneration

The effect of abscisic acid (ABA) on plant regeneration in anther-derived calli of rice Oryza sativa L. varieties Taipei 177, Taipei 309 and Fujisaka 5 was studied.ABA at concentrations up to 4×10(-6) M stimulated fresh weight increase in Taipei 309 and Fujisaka 5 while higher concentrations effected corresponding weight decreases in the three varieties tested. Relatively high ABA concentrations resulted in decreased callus size and production of more compact and whitish calli. ABA increased the frequency of calli producing green plants in Taipei 309 and the average green plant regeneration in all varieties tested.

Osmoregulation and membrane-mediated responses to altered water potential in plant cells

Plant cells respond to short-term stress dehydration by modification of internal psi pi such that an inward gradient of psi w is maintained. In response to lowered psi w, increases in internal psi pi are created by alteration of cell inorganic ions and small organic solute content. Passive movement of water follows, changing cell hydration and forcing the plasma membrane against the elastic cell wall. The stretched cell wall presses against the cell contents, creating a hydrostatic pressure, psi p, which tends to force water out of the cell. The resulting hydrostatic pressure eventually comes into equilibrium with forces bringing water into the cell, largely psi pi, and the net flow of water ceases. The mechanism for sensing cell psi w changes is unknown but the initial event must be physical, not biochemical. The method of translation of such physical events into biochemical actions is also unknown but the Zimmermann model provides a means of signal transduction and amplification, through the alteration of membrane parameters, which could account for the observed changes. As for animal cells, cell levels of Ca2+ are important for their regulation of membrane Pj in these responses but unlike osmoregulation in higher animals, the involvement of plant hormones in these responses have not been clearly established. However, the important role of plant cell limiting membranes in plant cell osmoregulation responses seems obvious.