GEm-Related 5 (GER5), an ABA and stress-responsive GRAM domain protein regulating seed development and inflorescence architecture.
We have identified an abscisic acid (ABA) and stress-responsive GRAM (Glucosyltransferases, Rab-like GTPase activators and Myotubularins) domain protein GER5 (GEm-Related 5) closely related to GEM (GLABRA2 Expression Modulator), a novel regulator of cell division and cell fate determination in epidermal cells. A loss-of-function T-DNA line (ger5-2) and transgenic lines silencing (GER5(RNAi)) or overexpressing (GER5(OE)) GER5 displayed several defects in reproductive development affecting seed and embryo development. RNA in situ studies revealed GER5 and related GRAM genes (GEM and GEm-Related 1 (GER1)) have both overlapping and unique expression domains in male and female reproductive organs. Hormone immunolocalization experiments further indicate GER5 transcripts preferentially localize to reproductive tissues which accumulate ABA. Expression analysis revealed members of the GRAM family (GER5, GER1, GEM) display tissue-specific expression patterns and are responsive to phytohormones and abiotic stress, in addition to genetic lesions (aba1, aba2, ctr1) affecting ABA biosynthesis or ethylene signalling. Mature seeds of ger5-2 mutants also exhibit reduced sensitivity to ABA during seed germination assays. Microarray analysis of aborting and developing seeds isolated from ger5-2 mutants revealed underlying transcriptional changes in carbohydrate metabolism, hormone signalling and catabolic processes (e.g. protein degradation, autophagy). Taken together, our results indicate ABA-responsive GRAM genes play a novel role in regulating the reproductive development of plants, and raise intriguing questions regarding the functional relationship between members of the GRAM gene family.
Department of Plant Science, University of Manitoba, Winnipeg, MB, Canada.
Kevin N
KN
Baron
Department of Biological Sciences, University of Manitoba, Winnipeg, MB, Canada.
Dana F
DF
Schroeder
Department of Plant Science, University of Manitoba, Winnipeg, MB, Canada. Electronic address: stasolla@ms.umanitoba.ca.
Claudio
C
Stasolla
D000040:Abscisic Acid / Q000494:pharmacology*; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D001343:Autophagy / Q000187:drug effects / Q000235:genetics; D050260:Carbohydrate Metabolism / Q000187:drug effects / Q000235:genetics; D018797:Cell Cycle Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D017343:Genes, Plant; D018525:Germination / Q000187:drug effects / Q000235:genetics; D017403:In Situ Hybridization; D056626:Inflorescence / Q000033:anatomy & histology* / Q000187:drug effects; D009154:Mutation / Q000235:genetics; D010641:Phenotype; D030821:Plants, Genetically Modified; D017434:Protein Structure, Tertiary; D012639:Seeds / Q000187:drug effects / Q000235:genetics / Q000254:growth & development*; D013312:Stress, Physiological / Q000187:drug effects* / Q000235:genetics
D029681:Arabidopsis Proteins; D018797:Cell Cycle Proteins; C000593590:GER5 protein, Arabidopsis; D000040:Abscisic Acid
Abscisic acid; Arabidopsis; Development; GRAM; Stress