ABORTED MICROSPORES Acts as a Master Regulator of Pollen Wall Formation in Arabidopsis.
Mature pollen is covered by durable cell walls, principally composed of sporopollenin, an evolutionary conserved, highly resilient, but not fully characterized, biopolymer of aliphatic and aromatic components. Here, we report that ABORTED MICROSPORES (AMS) acts as a master regulator coordinating pollen wall development and sporopollenin biosynthesis in Arabidopsis thaliana. Genome-wide coexpression analysis revealed 98 candidate genes with specific expression in the anther and 70 that showed reduced expression in ams. Among these 70 members, we showed that AMS can directly regulate 23 genes implicated in callose dissociation, fatty acids elongation, formation of phenolic compounds, and lipidic transport putatively involved in sporopollenin precursor synthesis. Consistently, ams mutants showed defective microspore release, a lack of sporopollenin deposition, and a dramatic reduction in total phenolic compounds and cutin monomers. The functional importance of the AMS pathway was further demonstrated by the observation of impaired pollen wall architecture in plant lines with reduced expression of several AMS targets: the abundant pollen coat protein extracellular lipases (EXL5 and EXL6), and CYP98A8 and CYP98A9, which are enzymes required for the production of phenolic precursors. These findings demonstrate the central role of AMS in coordinating sporopollenin biosynthesis and the secretion of materials for pollen wall patterning.
Collaborative Innovation Center for Genetics and Development, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China.
Jie
J
Xu
Collaborative Innovation Center for Genetics and Development, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China.
Zhiwen
Z
Ding
School of Biosciences, University of Nottingham, Loughborough, Leicestershire, LE125RD, United Kingdom.
Gema
G
Vizcay-Barrena
Collaborative Innovation Center for Genetics and Development, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China.
Jianxin
J
Shi
Collaborative Innovation Center for Genetics and Development, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China.
Wanqi
W
Liang
Collaborative Innovation Center for Genetics and Development, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China.
Zheng
Z
Yuan
Institut de Biologie Moléculaire des Plantes, Centre National de la Recherche Scientifique, Unité Propre de Recherche 2357-Université de Strasbourg, 67083 Strasbourg Cedex, France.
Danièle
D
Werck-Reichhart
Institute of Cellular and Molecular Botany, University of Bonn, D-53115 Bonn, Germany.
Lukas
L
Schreiber
School of Biosciences, University of Nottingham, Loughborough, Leicestershire, LE125RD, United Kingdom.
Zoe A
ZA
Wilson
Collaborative Innovation Center for Genetics and Development, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China zhangdb@sjtu.edu.cn.
Dabing
D
Zhang