Abscisic acid drought-induced

Quarrie, S.A. (1981). Genetic variability and heritability of drought-induced abscisic acid accumulation in spring wheat. Plant, Cell Environment, 4,147-51. 

Innes, P., Blackwell, R.D. Quarrie, S.A. (1984). Some effects of genetic variation in drought induced abscisic acid accumulation on the yield and water use of spring wheat. Journal of Agricultural Science, Cambridge, 102, 341-51. 

Iuchi, S., M. Kobayashi et al. (2000). A stress-inducible gene for 9-cw-epoxycarotenoid dioxygenase involved in abscisic acid biosynthesis under water stress in drought-tolerant cowpea. Plant Physiol. 123(2) 553-562. 

Drought stress also caused oxidative stress, as indicated by increase of H2O2 and increased antioxidant enzyme activities of SOD, GPX, and APX in Populus cuttings (Lei et al. 2007). APX activity was increased by drought, with or without abscisic acid (ABA), which is known to induce ROS, in young leaves of the ABA-delicient mutant notabilis. These data demonstrated that ROS are created in drought stress and affect antioxidant activities (Unyayar and Cekic 2005). 

Abscisic acid is a general plant-growth inhibitor. It induces dormancy and prevents seeds from germinating causes abscission of leaves, fruits, and flowers and causes stomata to close. High concentrations of abscisic acid in guard cells during periods of stress induced by drought probably have a role in stomatal closure. 

Abscisic acid is a sequiterpene phytohormone that is induced by drought and promotes stomatal closure and seed dormancy. Other sesquiterpenes take part in tritrophic plant-herbivore-parasite interactions (reviewed by Dudareva et al., 2006). In maize infested with lepidopteran larvae, the sesquiterpenes ( )-P-famesene and the ( )-a-bergamotene (Fig. 30) attract the parasitic wasp Cotesia marginiventris (Schnee et al., 2006). Maize roots release ( )-P-caryophyllene (Fig. 30) upon attack of larvae of the beetle Diabrotica virgifera to attract the parasitic nematode Heterorhabditis megidis (Rasmann et al., 2005). 

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