title: Gibberellic Acid-Stimulated Arabidopsis6 Serves as an Integrator of Gibberellin, Abscisic Acid, and Glucose Signaling during Seed Germination in Arabidopsis.
abstract: The DELLA protein REPRESSOR OF ga1-3-LIKE2 (RGL2) plays an important role in seed germination under different conditions through a number of transcription factors. However, the functions of the structural genes associated with RGL2-regulated germination are less defined. Here, we report the role of an Arabidopsis (Arabidopsis thaliana) cell wall-localized protein, Gibberellic Acid-Stimulated Arabidopsis6 (AtGASA6), in functionally linking RGL2 and a cell wall loosening expansin protein (Arabidopsis expansin A1 [AtEXPA1]), resulting in the control of embryonic axis elongation and seed germination. AtGASA6-overexpressing seeds showed precocious germination, whereas transfer DNA and RNA interference mutant seeds displayed delayed seed germination under abscisic acid, paclobutrazol, and glucose (Glc) stress conditions. The differences in germination rates resulted from corresponding variation in cell elongation in the hypocotyl-radicle transition region of the embryonic axis. AtGASA6 was down-regulated by RGL2, GLUCOSE INSENSITIVE2, and ABSCISIC ACID-INSENSITIVE5 genes, and loss of AtGASA6 expression in the gasa6 mutant reversed the insensitivity shown by the rgl2 mutant to paclobutrazol and the gin2 mutant to Glc-induced stress, suggesting that it is involved in regulating both the gibberellin and Glc signaling pathways. Furthermore, it was found that the promotion of seed germination and length of embryonic axis by AtGASA6 resulted from a promotion of cell elongation at the embryonic axis mediated by AtEXPA1. Taken together, the data indicate that AtGASA6 links RGL2 and AtEXPA1 functions and plays a role as an integrator of gibberellin, abscisic acid, and Glc signaling, resulting in the regulation of seed germination through a promotion of cell elongation.
authors.affiliation: Guangdong Provincial Key Laboratory of Biotechnology for Plant Development, School of Life Sciences, South China Normal University, Guangzhou 510631, China.
authors.forename: Chunmei
authors.identifier: http://orcid.org/0000-0001-5587-3747
authors.initials: C
authors.lastname: Zhong
authors.affiliation: Guangdong Provincial Key Laboratory of Biotechnology for Plant Development, School of Life Sciences, South China Normal University, Guangzhou 510631, China.
authors.forename: Hao
authors.identifier: http://orcid.org/0000-0002-4248-1768
authors.initials: H
authors.lastname: Xu
authors.affiliation: Guangdong Provincial Key Laboratory of Biotechnology for Plant Development, School of Life Sciences, South China Normal University, Guangzhou 510631, China.
authors.forename: Siting
authors.identifier: http://orcid.org/0000-0001-5579-3173
authors.initials: S
authors.lastname: Ye
authors.affiliation: Guangdong Provincial Key Laboratory of Biotechnology for Plant Development, School of Life Sciences, South China Normal University, Guangzhou 510631, China.
authors.forename: Shiyi
authors.identifier: http://orcid.org/0000-0003-2068-2208
authors.initials: S
authors.lastname: Wang
authors.affiliation: Guangdong Provincial Key Laboratory of Biotechnology for Plant Development, School of Life Sciences, South China Normal University, Guangzhou 510631, China.
authors.forename: Lingfei
authors.initials: L
authors.lastname: Li
authors.affiliation: Guangdong Provincial Key Laboratory of Biotechnology for Plant Development, School of Life Sciences, South China Normal University, Guangzhou 510631, China sczhang@scnu.edu.cn wangxj@scnu.edu.cn.
authors.forename: Shengchun
authors.initials: S
authors.lastname: Zhang
authors.affiliation: Guangdong Provincial Key Laboratory of Biotechnology for Plant Development, School of Life Sciences, South China Normal University, Guangzhou 510631, China sczhang@scnu.edu.cn wangxj@scnu.edu.cn.
authors.forename: Xiaojing
authors.identifier: http://orcid.org/0000-0002-4607-2398
authors.initials: X
authors.lastname: Wang
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism; D017360:Arabidopsis / Q000235:genetics* / Q000502:physiology; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002473:Cell Wall / Q000378:metabolism; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D018525:Germination; D005875:Gibberellins / Q000378:metabolism; D005947:Glucose / Q000378:metabolism; D010937:Plant Growth Regulators / Q000378:metabolism*; D012639:Seeds / Q000235:genetics / Q000502:physiology; D015398:Signal Transduction; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; C568127:EXPA1 protein, Arabidopsis; C000612876:GASA6 protein, Arabidopsis; D005875:Gibberellins; D010937:Plant Growth Regulators; C450823:RGL2 protein, Arabidopsis; D014157:Transcription Factors; D000040:Abscisic Acid; C007842:gibberellic acid; D005947:Glucose