High temperature-induced abscisic acid biosynthesis and its role in the inhibition of gibberellin action in Arabidopsis seeds Export

@article{citeulike:2192222, abstract = {Suppression of seed germination at supraoptimal high temperature (thermoinhibiton) during summer is crucial for Arabidopsis (Arabidopsis thaliana (L.) Heynh.) to establish vegetative and reproductive growth in appropriate seasons. Abscisic acid (ABA) and gibberellins (GAs) are well known to be involved in germination control, but it remains unknown how these hormone actions (metabolism and responsiveness) are altered at high temperature. Here we show that ABA levels in imbibed seeds are elevated at high temperature and that this increase is correlated with up-regulation of the zeaxanthin epoxidase gene, ABA1/ZEP and three 9-cis-epoxycarotenoid dioxygenase genes, NCED2, NCED5 and NCED9. Reverse genetic studies show that NCED9 plays a major, and NCED5 and NCED2 play relatively minor roles in high temperature-induced ABA synthesis and germination inhibition. We also show that bioactive GAs stay at low levels at high temperature, presumably through suppression of GA 20-oxidase genes, GA20ox1, GA20ox2, GA20ox3, and GA 3-oxidase genes, GA3ox1 and GA3ox2. Thermoinhibition tolerant germination of loss-of-function mutants of GA negative regulators, SPINDLY (SPY) and RGL2, suggests that repression of GA signaling is required for thermoinibition. Interestingly, ABA-deficient aba2-2 mutant seeds show significant expression of GA synthesis genes and repression of SPY expression even at high temperature. In addition, thermoinhibition resistant germination phenotype of aba2-1 seeds is suppressed by a GA biosynthesis inhibitor, paclobutrazol. We conclude that high temperature stimulates ABA synthesis, and represses GA synthesis and signaling through the action of ABA in Arabidopsis seeds. 10.1104/pp.107.113738}, author = {Toh, Shigeo and Imamura, Akane and Watanabe, Asuka and Nakabayashi, Kazumi and Okamoto, Masanori and Jikumaru, Yusuke and Hanada, Atsushi and Aso, Yukie and Ishiyama, Kanako and Tamura, Noriko and Iuchi, Satoshi and Kobayashi, Masatomo and Yamaguchi, Shinjiro and Kamiya, Yuji and Nambara, Eiji and Kawakami, Naoto}, citeulike-article-id = {2192222}, citeulike-linkout-0 = {http://dx.doi.org/10.1104/pp.107.113738}, citeulike-linkout-1 = {http://view.ncbi.nlm.nih.gov/pubmed/18162586}, citeulike-linkout-2 = {http://www.hubmed.org/display.cgi?uids=18162586}, day = {27}, doi = {10.1104/pp.107.113738}, journal = {Plant Physiol.}, keywords = {aba, ga, high-temperature}, month = {December}, pages = {pp.107.113738+}, posted-at = {2008-01-03 20:31:10}, priority = {2}, title = {High temperature-induced abscisic acid biosynthesis and its role in the inhibition of gibberellin action in Arabidopsis seeds}, url = {http://dx.doi.org/10.1104/pp.107.113738}, year = {2007} }

TY - JOUR ID - citeulike:2192222 L3 - citeulike-article-id:2192222 N2 - Suppression of seed germination at supraoptimal high temperature (thermoinhibiton) during summer is crucial for Arabidopsis (Arabidopsis thaliana (L.) Heynh.) to establish vegetative and reproductive growth in appropriate seasons. Abscisic acid (ABA) and gibberellins (GAs) are well known to be involved in germination control, but it remains unknown how these hormone actions (metabolism and responsiveness) are altered at high temperature. Here we show that ABA levels in imbibed seeds are elevated at high temperature and that this increase is correlated with up-regulation of the zeaxanthin epoxidase gene, ABA1/ZEP and three 9-cis-epoxycarotenoid dioxygenase genes, NCED2, NCED5 and NCED9. Reverse genetic studies show that NCED9 plays a major, and NCED5 and NCED2 play relatively minor roles in high temperature-induced ABA synthesis and germination inhibition. We also show that bioactive GAs stay at low levels at high temperature, presumably through suppression of GA 20-oxidase genes, GA20ox1, GA20ox2, GA20ox3, and GA 3-oxidase genes, GA3ox1 and GA3ox2. Thermoinhibition tolerant germination of loss-of-function mutants of GA negative regulators, SPINDLY (SPY) and RGL2, suggests that repression of GA signaling is required for thermoinibition. Interestingly, ABA-deficient aba2-2 mutant seeds show significant expression of GA synthesis genes and repression of SPY expression even at high temperature. In addition, thermoinhibition resistant germination phenotype of aba2-1 seeds is suppressed by a GA biosynthesis inhibitor, paclobutrazol. We conclude that high temperature stimulates ABA synthesis, and represses GA synthesis and signaling through the action of ABA in Arabidopsis seeds. 10.1104/pp.107.113738 JF - Plant Physiol. TI - High temperature-induced abscisic acid biosynthesis and its role in the inhibition of gibberellin action in Arabidopsis seeds SP - pp.107.113738 KW - aba KW - ga KW - high-temperature AU - Toh, Shigeo AU - Imamura, Akane AU - Watanabe, Asuka AU - Nakabayashi, Kazumi AU - Okamoto, Masanori AU - Jikumaru, Yusuke AU - Hanada, Atsushi AU - Aso, Yukie AU - Ishiyama, Kanako AU - Tamura, Noriko AU - Iuchi, Satoshi AU - Kobayashi, Masatomo AU - Yamaguchi, Shinjiro AU - Kamiya, Yuji AU - Nambara, Eiji AU - Kawakami, Naoto PY - 2007/12/27/ UR - http://dx.doi.org/10.1104/pp.107.113738 ER -