Wheat Ppd-1 allelic combination modulates photoperiod sensitivity.

THOMAS PEREZ GIANMARCO; SEVERINI, ALAN; GONZÁLEZ, FERNANDA G

Congreso; XXXII Reunión argentina, XVI Congreso latinoamericano de fisiología vegetal.; 2018

Field trials for phenologic characterisation of germplasm and evaluation of new varieties are resource consuming, yet necessary. Genotypic characterisation, on the other hand, is getting cheaper and easier. Thus, a model linking Ppd-1 allelic composition to phenotype ?its phenology? would allow to replace such trials. A photoperiod-sensitive cultivar, Paragon, and four near-isogenic lines carrying single Ppd-1a insensitivity alleles and their triple combination were tested under a range of natural and extended photoperiod. The timing of phonologic were recorded, including leaf appearance. Durations of i) the whole cycle ?emergence through anthesis?, ii) emergence through onset of stem elongation (OSE), and iii) OSE to anthesis, were related to mean photoperiod. Ppd-1a alleles, and their stacking, decreased photoperiod sensitivity for the whole cycle to anthesis from 200 to 50 ºC d h-1, with negligible effect on threshold photoperiod (17.2-17.4 h) or intrinsic earliness (950-890 ºC d). Photoperiod sensitivity from emergence to OSE responded similarly. Photoperiod response from OSE to anthesis was milder and duration of the phase was better explained when leaves to be appeared from OSE onwards were considered. After validation, these data would allow a model to predict photoperiod response of any genotype, given its Ppd-1 allelic combination.