AtbZIP34 is required for Arabidopsis pollen wall patterning and the control of several metabolic pathways in developing pollen.
Sexual plant reproduction depends on the production and differentiation of functional gametes by the haploid gametophyte generation. Currently, we have a limited understanding of the regulatory mechanisms that have evolved to specify the gametophytic developmental programs. To unravel such mechanisms, it is necessary to identify transcription factors (TF) that are part of such haploid regulatory networks. Here we focus on bZIP TFs that have critical roles in plants, animals and other kingdoms. We report the functional characterization of Arabidopsis thaliana AtbZIP34 that is expressed in both gametophytic and surrounding sporophytic tissues during flower development. T-DNA insertion mutants in AtbZIP34 show pollen morphological defects that result in reduced pollen germination efficiency and slower pollen tube growth both in vitro and in vivo. Light and fluorescence microscopy revealed misshapen and misplaced nuclei with large lipid inclusions in the cytoplasm of atbzip34 pollen. Scanning and transmission electron microscopy revealed defects in exine shape and micropatterning and a reduced endomembrane system. Several lines of evidence, including the AtbZIP34 expression pattern and the phenotypic defects observed, suggest a complex role in male reproductive development that involves a sporophytic role in exine patterning, and a sporophytic and/or gametophytic mode of action of AtbZIP34 in several metabolic pathways, namely regulation of lipid metabolism and/or cellular transport.
Gibalová
Antónia
A
Laboratory of Pollen Biology, Institute of Experimental Botany ASCR, Rozvojová 263, Prague 6, Czech Republic.
Renák
David
D
Matczuk
Katarzyna
K
Dupl'áková
Nikoleta
N
Cháb
David
D
Twell
David
D
Honys
David
D
D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000502:physiology*; D002473:Cell Wall / Q000378:metabolism / Q000648:ultrastructure; D035264:Flowers / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D020869:Gene Expression Profiling; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D005816:Genetic Complementation Test; D053858:Metabolic Networks and Pathways / Q000235:genetics / Q000502:physiology*; D008855:Microscopy, Electron, Scanning; D046529:Microscopy, Electron, Transmission; D008856:Microscopy, Fluorescence; D009154:Mutation; D030821:Plants, Genetically Modified; D011058:Pollen / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D053205:Pollen Tube / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015534:Trans-Activators / Q000235:genetics / Q000502:physiology*
D029681:Arabidopsis Proteins; D015534:Trans-Activators; C542093:bZIP34 protein, Arabidopsis