Accumulation of High Levels of ABA Regulates the Pleiotropic Response of the nhr1 Arabidopsis Mutant

다국어 초록 (Multilingual Abstract)

Plants have evolved a variety of mechanisms for responding to environmental cues, which allows them to survive in the presence of limited resources or environmental stresses. One of the most significant growth adaptations plants have attained is tropism, a growth response that involves bending of plant organs toward or away from a stimulus. Roots exhibit hydrotropism in response to moisture gradients, which is thought to be critical in acquiring water and establishing their stand in the soil. However, the mechanism underlying hydrotropism remains unsolved. Here, we report that the no hydrotropic response (nhr1) mutant of Arabidopsis, which is impaired in hydrotropism, is tolerant to drought. The no hydrotropic response phenotype of nhr1 was repressed by AbamineSG,an inhibitor of abscisic acid (ABA) biosynthesis, indicating that ABA negatively regulates hydrotropism. Furthermore,the content of ABA was higher in nhr1 compared to those of wild type (wt). However, the higher ABA levels in nhr1plants were not due to higher transcript levels of 9-cisepoxycarotenoid dioxygenase (NCED3), since these were diminished compared to those of wt. Our results indicated that the root hydrotropic response of the nhr1 mutant is modulated by ABA and that the higher ABA levels of the mutant might confer it drought resistance.

참고문헌 (Reference)

1 Darwin C, "The power of movement in plants" D. Appleton and Co. 1-592, 1881

2 Koornneef M, "The isolation and characterization of abscisic acid-insensitive mutants of Arabidopsis thaliana" 61 : 377-383, 1984

3 Niklas KJ, "The evolutionary biology of plants" The University of Chicago Press 1-449, 1997

4 Miyazawa Y, "The GNOM-mediated vesicular trafficking plays an essential role in hydrotropism of Arabidopsis roots" 149 : 835-840, 2008

5 Miyazawa Y, "The GNOM-mediated vesicular trafficking plays an essential role in hydrotropism of Arabidopsis roots" 149 : 835-840, 2009

6 Schwartz SH, "Specific oxidative cleavage of carotenoids by VP14 of Maize" 276 : 1872-1874, 1997

7 de Dorlodot S, "Root system architecture: opportunities and constraints for genetic improvement of crops" 12 : 474-481, 2007

8 Sharp RE, "Root growth maintenance during water deficits: physiology to functional genomics" 55 : 2343-2351, 2004

9 Ho MD, "Root architectural tradeoffs for water and phosphorus acquisition" 32 : 737-748, 2005

10 Ponce G, "Roles of amyloplasts and water deficit in root tropisms" 31 : 205-217, 2008

11 Shinozaki K, "Regulatory network of gene expression in the drought and cold stress responses" 6 : 410-417, 2003

12 Iuchi S, "Regulation of drought tolerance by gene manipulation of 9-cisepoxycarotenoid dioxygenase, a key enzyme in abscisic acid biosynthesis in Arabidopsis" 27 : 325-333, 2001

13 Nelson DE, "Plant nuclear factor Y (NF-Y) B subunits confer drought tolerance and lead to improved corn yields on water-limited acres" 104 (104): 16450-16455, 2007

14 Bernier G, "Physiological signals that induce flowering" 5 : 1147-1155, 1993

15 Dai X, "Overexpression of an R1R2R3MYB Gene, OsMYB3R-2, increases tolerance to freezing, drought, and salt stress in transgenic Arabidopsis" 143 : 1739-1751, 2007

16 Cassab GI, "Other tropisms and relationship to gravitropism. in : Plant tropisms" Blackwell 123-139, 2008

17 Yamaguchi-Shinozaki K, "Organization of cisacting regulatory elements in osmotic- and cold-stress-responsive promoters" 10 : 88-94, 2005

18 Ho MD, "Optimization modeling of plant root architecture for water and phosphorus acquisition" 226 : 331-340, 2004

19 Kasuga M, "Improving plant drought, salt, and freezing tolerance by gene transfer of a single stress-inducible transcription factor" 17 : 287-291, 1999

20 Xiong L, "Identification of drought tolerance determinants by genetic analysis of root response to drought stress and abscisic acid" 142 : 1065-1074, 2006

21 Eapen D, "Hydrotropism: root growth responses to water" 10 : 44-50, 2005

22 Takahashi N, "Hydrotropism interacts with gravitropism by degrading amyloplasts in seedling roots of Arabidopsis and radish" 132 : 805-810, 2003

23 Battisti D, "Historical warnings of future food insecurity with unprecedented seasonal heat" 323 : 240-244, 2009

24 Shinozaki K, "Gene networks involved in drought stress response and tolerance" 58 : 221-227, 2007

25 Zhang JZ, "From laboratory to field. Using information from Arabidopsis to engineer salt, cold, and drought tolerance in crops" 135 : 615-621, 2004

26 Lynch J, "Ethylene and plant responses to nutritional stress" 100 : 613-619, 1997

27 Vartanian N, "Drought rhizogenesis in Arabidopsis thaliana (differential responses of hormonal mutants)" 104 : 761-767, 1994

28 Gubler F, "Dormancy release, ABA and pre-harvest sprouting" 8 : 183-187, 2005

29 Ali-Rachedi S, "Changes in endogenous abscisic acid levels during dormancy release and maintenance of mature seeds: studies with the Cape Verde Islands ecotype, the dormant model of Arabidopsis thaliana" 219 : 479-488, 2004

30 Simpson GG, "Arabidopsis, the Rosetta stone of flowering time?" 296 : 285-289, 2002

31 Nishimura N, "Analysis of ABA hypersensitive germination2 revealed the pivotal functions of PARN in stress response in Arabidopsis" 44 : 972-984, 2005

32 Bohnert HJ, "Adaptations to environmental stresses" 7 : 1099-1111, 1995

33 Finkelstein RR, "Abscisic acid signaling in seeds and seedlings" 14 : S15-S45, 2002

34 Murashige T, "A revised medium for rapid growth and bioassays with tobacco tissue cultures" 15 : 473-497, 1962

35 De Smet I, "A novel role for abscisic acid emerges from underground" 11 : 434-439, 2006

36 Han SY, "A novel inhibitor of 9-cis-epoxycarotenoid dioxygenase in abscisic acid biosynthesis in higher plants" 135 : 1574-1582, 2004

37 Eapen D, "A no hydrotropic response root mutant that responds positively to gravitropism in Arabidopsis" 131 : 536-546, 2003

38 Rossel JB, "A mutation affecting ASCORBATE PEROXIDASE 2 gene expression reveals a link between responses to high light and drought tolerance" 29 : 269-281, 2006

39 Kobayashi A, "A gene essential for hydrotropism in roots" 104 : 4724-4729, 2007

40 Kitahata N, "A 9-cis-epoxycarotenoid dioxygenase inhibitor for use in the elucidation of abscisic acid action mechanisms" 14 : 5555-5561, 2006