Wheat pre-anthesis development as affected by photoperiod sensitivity genes (Ppd-1) under contrasting photoperiods

Fine tuning wheat phenology is of paramount importance for adaptation. A better understanding of how genetic constitution modulates the developmental responses during pre-anthesis phases would help to maintain or even increase yield potential as temperature increases due to climate change. The photoperiod-sensitive cultivar Paragon, and four near isogenic lines with different combinations of insensitivity alleles (Ppd-A1a, Ppd-B1a, Ppd-D1a or their triple stack) were evaluated under short (12 h) and long (16 h) photoperiods. Insensitivity alleles decreased time to anthesis and duration of the three pre-anthesis phases (vegetative, early reproductive and late reproductive), following the Ppd-D1a > Ppd-A1a > Ppd-B1a ranking of strength. Stacking them intensified the insensitivity, but had no additive effect over that of Ppd-D1a. The late reproductive phase was the most responsive, even exhibiting a qualitative response. Leaf plastochron was not affected but spikelet plastochron increased according to Ppd-1a ranking of strength. Earlier anthesis resulted from less leaves differentiated and a fine tuning effect of accelerated rate of leaf appearance. None of the alleles affected development exclusively during any particular pre-anthesis phase, which would be ideal for tailoring time to anthesis with specific partitioning of developmental time into particular phases. Other allelic variants should be further tested to this purpose.EEA PergaminoFil: Pérez-Gianmarco, Thomas. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Pergamino. Departamento Ecofisiología; Argentina. University of Lleida. Department of Crop and Forest Sciences; España.Fil: Slafer, Gustavo A. University of Lleida. Department of Crop and Forest Sciences; España. ICREA (Catalonian Institution for Research and Advanced Studies); España. University of Lleida . AGROTECNIO (Centre for Research in Agrotechnology); España.Fil: González, Fernanda G. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Pergamino. Departamento Ecofisiología; Argentina.CONICET-UNNOBA.CITNOBA; Argentina