title: Overexpression of a NAC transcription factor delays leaf senescence and increases grain nitrogen concentration in wheat.
abstract: Increasing the duration of leaf photosynthesis during grain filling using slow-senescing functional stay-green phenotypes is a possible route for increasing grain yields in wheat (Triticum aestivum L.). However, delayed senescence may negatively affect nutrient remobilisation and hence reduce grain protein concentrations and grain quality. A novel NAC1-type transcription factor (hereafter TaNAC-S) was identified in wheat, with gene expression located primarily in leaf/sheath tissues, which decreased during post-anthesis leaf senescence. Expression of TaNAC-S in the second leaf correlated with delayed senescence in two doubled-haploid lines of an Avalon × Cadenza population (lines 112 and 181), which were distinct for leaf senescence. Transgenic wheat plants overexpressing TaNAC-S resulted in delayed leaf senescence (stay-green phenotype). Grain yield, aboveground biomass, harvest index and total grain N content were unaffected, but NAC over-expressing lines had higher grain N concentrations at similar grain yields compared to non-transgenic controls. These results indicate that TaNAC-S is a negative regulator of leaf senescence, and that delayed leaf senescence may lead not only to increased grain yields but also to increased grain protein concentrations.
authors.affiliation: Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xi'ning, Qing'hai, China.|Plant Biology and Crop Science Department, Rothamsted Research, Harpenden, UK.|University of Chinese Academy of Sciences, Beijing, China.
authors.forename: D
authors.initials: D
authors.lastname: Zhao
authors.affiliation: Plant Biology and Crop Science Department, Rothamsted Research, Harpenden, UK.
authors.forename: A P
authors.initials: AP
authors.lastname: Derkx
authors.affiliation: Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xi'ning, Qing'hai, China.
authors.forename: D-C
authors.initials: DC
authors.lastname: Liu
authors.affiliation: Plant Biology and Crop Science Department, Rothamsted Research, Harpenden, UK.
authors.forename: P
authors.initials: P
authors.lastname: Buchner
authors.affiliation: Plant Biology and Crop Science Department, Rothamsted Research, Harpenden, UK.
authors.forename: M J
authors.initials: MJ
authors.lastname: Hawkesford
mesh_terms: D001483:Base Sequence; D018533:Biomass; D002523:Edible Grain / Q000235:genetics / Q000502:physiology; D015870:Gene Expression; D018506:Gene Expression Regulation, Plant; D008969:Molecular Sequence Data; D009584:Nitrogen / Q000032:analysis / Q000378:metabolism*; D010641:Phenotype; D010788:Photosynthesis; D010802:Phylogeny; D018515:Plant Leaves / Q000235:genetics / Q000502:physiology; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified; D012273:Ribulose-Bisphosphate Carboxylase / Q000235:genetics / Q000378:metabolism; D017422:Sequence Analysis, DNA; D013997:Time Factors; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D014908:Triticum / Q000235:genetics / Q000502:physiology*
chemical_list: D010940:Plant Proteins; D014157:Transcription Factors; D012273:Ribulose-Bisphosphate Carboxylase; D009584:Nitrogen
keywords: Grain protein deviation; NAC gene family; Triticum aestivum; nitrogen remobilisation; rubisco; yield