title: Expression patterns of ABA and GA metabolism genes and hormone levels during rice seed development and imbibition: a comparison of dormant and non-dormant rice cultivars.
abstract: Seed dormancy is an important agronomic trait in cereals. Using deep dormant (N22), medium dormant (ZH11), and non-dormant (G46B) rice cultivars, we correlated seed dormancy phenotypes with abscisic acid (ABA) and gibberellin (GA) metabolism gene expression profiles and phytohormone levels during seed development and imbibition. A time course analysis of ABA and GA content during seed development showed that N22 had a high ABA level at early and middle seed developmental stages, while at late developmental stage it declined to the level of ZH11; however, its ABA/GA ratio maintained at a high level throughout seed development. By contrast, G46B had the lowest ABA content during seed development though at early developmental stage its ABA level was close to that of ZH11, and its ABA/GA ratio peaked at late developmental stage that was at the same level of ZH11. Compared with N22 and G46B, ZH11 had an even and medium ABA level during seed development and its ABA/GA ratio peaked at the middle developmental stage. Moreover, the seed development time-point having high ABA/GA ratio also had relatively high transcript levels for key genes in ABA and GA metabolism pathways across three cultivars. These indicated that the embryo-imposed dormancy has been induced before the late developmental stage and is determined by ABA/GA ratio. A similar analysis during seed imbibition showed that ABA was synthesized in different degrees for the three cultivars. In addition, water uptake assay for intact mature seeds suggested that water could permeate through husk barrier into seed embryo for all three cultivars; however, all three cultivars showed distinct colors by vanillin-staining indicative of the existence of flavans in their husks, which are dormancy inhibition compounds responsible for the husk-imposed dormancy.
authors: State Key Laboratory of Plant Genomics and National Center for Plant Gene Research (Beijing), Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China; National Center for Plant Gene Research (Beijing), Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China.
authors: Yang
authors: Y
authors: Liu
authors: State Key Laboratory of Plant Genomics and National Center for Plant Gene Research (Beijing), Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China.
authors: Jun
authors: J
authors: Fang
authors: State Key Laboratory of Plant Genomics and National Center for Plant Gene Research (Beijing), Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China.
authors: Fan
authors: F
authors: Xu
authors: National Center for Plant Gene Research (Beijing), Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China.
authors: Jinfang
authors: J
authors: Chu
authors: National Center for Plant Gene Research (Beijing), Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China.
authors: Cunyu
authors: C
authors: Yan
authors: Department of Biological Sciences, Marquette University, Milwaukee 53233, USA.
authors: Michael R
authors: MR
authors: Schläppi
authors: College of Life Sciences, Yangzhou University, Yangzhou 225009, China.
authors: Youping
authors: Y
authors: Wang
authors: State Key Laboratory of Plant Genomics and National Center for Plant Gene Research (Beijing), Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China. Electronic address: ccchu@genetics.ac.cn.
authors: Chengcai
authors: C
authors: Chu
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism*; D005875:Gibberellins / Q000378:metabolism*; D006728:Hormones / Q000378:metabolism*; D012275:Oryza / Q000235:genetics* / Q000254:growth & development; D057445:Plant Dormancy; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D012639:Seeds / Q000235:genetics* / Q000254:growth & development; D059467:Transcriptome
chemical_list: D005875:Gibberellins; D006728:Hormones; D010940:Plant Proteins; D000040:Abscisic Acid
keywords: ABA/GA ratio; Abscisic acid (ABA); Gene expression; Gibberellin (GA); Rice; Seed development; Seed imbibition