title: Functional characterization of GPC-1 genes in hexaploid wheat.
abstract: In wheat, monocarpic senescence is a tightly regulated process during which nitrogen (N) and micronutrients stored pre-anthesis are remobilized from vegetative tissues to the developing grains. Recently, a close connection between senescence and remobilization was shown through the map-based cloning of the GPC (grain protein content) gene in wheat. GPC-B1 encodes a NAC transcription factor associated with earlier senescence and increased grain protein, iron and zinc content, and is deleted or non-functional in most commercial wheat varieties. In the current research, we identified 'loss of function' ethyl methanesulfonate mutants for the two GPC-B1 homoeologous genes; GPC-A1 and GPC-D1, in a hexaploid wheat mutant population. The single gpc-a1 and gpc-d1 mutants, the double gpc-1 mutant and control lines were grown under field conditions at four locations and were characterized for senescence, GPC, micronutrients and yield parameters. Our results show a significant delay in senescence in both the gpc-a1 and gpc-d1 single mutants and an even stronger effect in the gpc-1 double mutant in all the environments tested in this study. The accumulation of total N in the developing grains showed a similar increase in the control and gpc-1 plants until 25 days after anthesis (DAA) but at 41 and 60 DAA the control plants had higher grain N content than the gpc-1 mutants. At maturity, GPC in all mutants was significantly lower than in control plants while grain weight was unaffected. These results demonstrate that the GPC-A1 and GPC-D1 genes have a redundant function and play a major role in the regulation of monocarpic senescence and nutrient remobilization in wheat.
authors.affiliation: Faculty of Life Sciences, Dept. of Molecular Biology and Ecology of Plants, Tel Aviv University, 69978, Israel.
authors.forename: Raz
authors.initials: R
authors.lastname: Avni
authors.affiliation: Department of Plant Nutrition, College of Resources and Environmental Science, China Agricultural University, Beijing, 100193, P.R. China.|Dept. of Plant Sciences, University of California, Davis, CA, 95616, USA.
authors.forename: Rongrong
authors.initials: R
authors.lastname: Zhao
authors.affiliation: Dept. of Plant Sciences, University of California, Davis, CA, 95616, USA.
authors.forename: Stephen
authors.initials: S
authors.lastname: Pearce
authors.affiliation: Dept. of Evolutionary and Environmental Biology, University of Haifa, Mt. Carmel, Haifa, 31905, Israel.
authors.forename: Yan
authors.initials: Y
authors.lastname: Jun
authors.affiliation: Dept. of Plant Sciences, University of California, Davis, CA, 95616, USA.
authors.forename: Cristobal
authors.initials: C
authors.lastname: Uauy
authors.affiliation: Dept. of Plant Sciences, University of California, Davis, CA, 95616, USA.
authors.forename: Facundo
authors.initials: F
authors.lastname: Tabbita
authors.affiliation: Dept. of Evolutionary and Environmental Biology, University of Haifa, Mt. Carmel, Haifa, 31905, Israel.
authors.forename: Tzion
authors.initials: T
authors.lastname: Fahima
authors.affiliation: Arcadia Biosciences Inc., Seattle, WA 98119, USA.
authors.forename: Ann
authors.initials: A
authors.lastname: Slade
authors.affiliation: Dept. of Plant Sciences, University of California, Davis, CA, 95616, USA.
authors.forename: Jorge
authors.initials: J
authors.lastname: Dubcovsky
authors.affiliation: Faculty of Life Sciences, Dept. of Molecular Biology and Ecology of Plants, Tel Aviv University, 69978, Israel.
authors.forename: Assaf
authors.initials: A
authors.lastname: Distelfeld
mesh_terms: D001692:Biological Transport; D018533:Biomass; D002734:Chlorophyll / Q000378:metabolism; D002523:Edible Grain / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D005020:Ethyl Methanesulfonate; D018506:Gene Expression Regulation, Plant; D055786:Gene Knockout Techniques; D007501:Iron / Q000032:analysis / Q000378:metabolism; D018977:Micronutrients / Q000378:metabolism; D009154:Mutation; D009584:Nitrogen / Q000378:metabolism; D010641:Phenotype; D010788:Photosynthesis; D018515:Plant Leaves / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D010940:Plant Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified; D013997:Time Factors; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D014908:Triticum / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D015032:Zinc / Q000032:analysis / Q000378:metabolism
chemical_list: D018977:Micronutrients; D010940:Plant Proteins; D014157:Transcription Factors; D002734:Chlorophyll; D005020:Ethyl Methanesulfonate; D007501:Iron; D015032:Zinc; D009584:Nitrogen