title: Wheat Grain Filling Is Limited by Grain Filling Capacity rather than the Duration of Flag Leaf Photosynthesis: A Case Study Using NAM RNAi Plants.
abstract: It has been proposed that delayed leaf senescence can extend grain filling duration and thus increase yields in cereal crops. We found that wheat (Triticum aestivum) NAM RNAi plants with delayed senescence carried out 40% more flag leaf photosynthesis after anthesis than control plants, but had the same rate and duration of starch accumulation during grain filling and the same final grain weight. The additional photosynthate available in NAM RNAi plants was in part stored as fructans in the stems, whereas stem fructans were remobilised during grain filling in control plants. In both genotypes, activity of starch synthase was limiting for starch synthesis in the later stages of grain filling. We suggest that in order to realise the potential yield gains offered by delayed leaf senescence, this trait should be combined with increased grain filling capacity.
authors.affiliation: John Innes Centre, Norwich Research Park, Norwich, United Kingdom.
authors.forename: Philippa
authors.initials: P
authors.lastname: Borrill
authors.affiliation: John Innes Centre, Norwich Research Park, Norwich, United Kingdom.
authors.forename: Brendan
authors.initials: B
authors.lastname: Fahy
authors.affiliation: John Innes Centre, Norwich Research Park, Norwich, United Kingdom.
authors.forename: Alison M
authors.initials: AM
authors.lastname: Smith
authors.affiliation: John Innes Centre, Norwich Research Park, Norwich, United Kingdom; National Institute of Agricultural Botany, Cambridge, United Kingdom.
authors.forename: Cristobal
authors.initials: C
authors.lastname: Uauy
mesh_terms: D000383:Agriculture / Q000379:methods; D005630:Fructans / Q000378:metabolism; D018977:Micronutrients / Q000378:metabolism; D009929:Organ Size; D010788:Photosynthesis; D018515:Plant Leaves / Q000502:physiology*; D010940:Plant Proteins / Q000235:genetics / Q000502:physiology; D030821:Plants, Genetically Modified; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000235:genetics; D012097:Repressor Proteins / Q000235:genetics / Q000502:physiology; D012639:Seeds / Q000254:growth & development / Q000378:metabolism; D013213:Starch / Q000378:metabolism; D014908:Triticum / Q000235:genetics / Q000254:growth & development*
chemical_list: D005630:Fructans; D018977:Micronutrients; D010940:Plant Proteins; D034741:RNA, Small Interfering; D012097:Repressor Proteins; D013213:Starch