title: Dynamic analysis of ABA accumulation in relation to the rate of ABA catabolism in maize tissues under water deficit.
abstract: The plant hormone abscisic acid (ABA) accumulates in plant tissues which experience water deficit (stress ABA). This study analysed its accumulation as a function of both synthesis and catabolism in maize tissues. By following the disappearance of the stress ABA when ABA synthesis was blocked by nordihydroguaiaretic acid (NDGA), the rate of the catabolism of stress ABA was determined. When compared with the catabolic rate of baseline (non-stress) ABA, stress ABA showed a catabolic rate >11 times higher. With such an elevated catabolic rate, it is proposed that the xanthophyll precursor pool may not be able to sustain the ABA accumulation, and such a proposition has been substantiated by further experiments where fluridone is used to limit the availability of upstream ABA precursors. When fluridone was used, stress ABA accumulation could only be sustained for a few hours, i.e. approximately 5 h for leaf and 1 h for root tissues. In detached roots, stress ABA accumulation could not be sustained even if fluridone was not used, suggesting that stress ABA accumulation in root systems requires the continuous import of ABA precursors from the shoots. Such an assumption was substantiated by the observation that defoliation or shading significantly reduced ABA accumulation in intact roots. The present study suggests that ABA catabolism is rapid enough to play an important role in the regulation of ABA accumulation.
authors.affiliation: College of Agronomy and Biotechnology, State Key Laboratory of Plant Physiology and Biochemistry, China Agricultural University, Beijing, China.
authors.forename: Huibo
authors.initials: H
authors.lastname: Ren
authors.forename: Zhihui
authors.initials: Z
authors.lastname: Gao
authors.forename: Lin
authors.initials: L
authors.lastname: Chen
authors.forename: Kaifa
authors.initials: K
authors.lastname: Wei
authors.forename: Jing
authors.initials: J
authors.lastname: Liu
authors.forename: Yijuan
authors.initials: Y
authors.lastname: Fan
authors.forename: William J
authors.initials: WJ
authors.lastname: Davies
authors.forename: Wensuo
authors.initials: W
authors.lastname: Jia
authors.forename: Jianhua
authors.initials: J
authors.lastname: Zhang
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism*; D000222:Adaptation, Physiological; D018515:Plant Leaves; D018517:Plant Roots / Q000378:metabolism; D018520:Plant Shoots / Q000378:metabolism; D014867:Water / Q000378:metabolism*; D003313:Zea mays / Q000378:metabolism*
chemical_list: D014867:Water; D000040:Abscisic Acid