Physiology and Molecular Biology of Stress ... - KHAM PHA MOI

Freezing Stress
147
Phospholiphase releases membrane linolenic acid, the precursor to oxylipins and JA
(Bergey et al., 1996). The combination of oxylipins, JA and ethylene act synergistically
to induce the expression of stress associated genes (O’Donnell et al., 2003). Abiotic
stress results in a JA mediated induction of wound related genes and the synthesis of
proteinase inhibitors (Conconi et al., 1996), which are also activated by water deficit,
salinity and ABA (Chao et al., 1999). Salicylic acid (SA), which plays a key role in plant
disease resistance and hypersensitive cell death, is involved in acclimation to abiotic
stresses. Exogenous SA increased abiotic stress tolerance by reducing reactive oxygen
species (ROS) in bean and tomato (Ding et al., 2002), as well as increasing cold
tolerance in wheat (Gusta unpublished results). Glutathione S-transferase (GST) genes
code for glutathione, which is involved in the binding and transport of hormones and in
the reduction of ROS (Edwards et al., 2000). It is interesting to note that the GST genes
are also activated by auxins and JA (Chen and Singh, 1999). Glutathione, acting as a
ROS scavenger, has long been implicated in freezing injury (McKersie and Bowley,
1996). McKersie et al., (1996) were among the first to propose death of winter annuals
was caused by the formation of ROS during prolonged periods of freeze-induced dehydration.
Thus, hormones comprise a very complex network of signalling molecules at
the cellular level. This has led to the suggestion that phytohormone responses cannot
be reduced to simple linear pathways that connect inputs and outputs but are more
probably by interactive networks (Moller and Chuaa, 1999, Gazzarrini and McCourt,
2003).
To date, a complete analysis of phytohormonal involvement in cold acclimation
has not been performed. Recently, a highly sensitive and selective method for the
simultaneous profiling and quantification of a wide variety of plant hormone groups
and their metabolites using high-performance liquid chromatography (HPLC) coupled
with electrospray ionization-tandem mass spectrometry (ESI-MS/MS) has been developed
(Chiwocha et al., 2003). Each compound is analyzed in its native state without the
need for derivatization. High temperatures are not required since the compounds are
separated by HPLC and the plant hormones and metabolites are analyzed using either
positive or negative ion electrospray in a single LC-MS/MS run. To date, over 20
compounds with hormonal activity can be analyzed and quantified simultaneously.
7. REFERENCES
Abeles F.B. (1966). Auxin stimulation of ethylene production. Plant Physiol. 41, 585-588.
Andrews C.J. and Pomeroy, M.K. (1978). The effect of anaerobic metabolites on survival and ultrastructure
of winter wheat in relation to ice encasement. Plant Physiol. 61, (suppl 17).
Arroyo A., Bossi, F., Finkelstein R.R. and León. P. (2003). Three genes that affect sugar sensing
(abscisic acid insensitive 4, abscisic acid insensitive 5 and constitute triple response 1) are
differentially regulated by glucan in Arabidopsis. Plant Physiol. 133, 231-242.
Atanassova, R., Leterrier, M., Gaillard, C., Agasse, A., Sagot, E., Coutos-Théand P. and Delrot, S.
(2003). Sugar-regulated expression of a putative hexose transport gene in grape. Plant Physiol.
131, 326-334.
Bae, M.S., Cho, E.J., Choi E.Y. and Park, O.K. (2003). Analysis of the Arabidopsis nuclear proteome