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

Abstract

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.

Dynamics of leaf and spikelet primordia initiation in wheat as affected by Ppd-1a alleles under field conditions

“… Miglietta, 1989 ; Slafer and Rawson, 1994 b ), disregarding whether the length of the phase was determined in thermal time or in phyllochrons. This is because, in agreement with previous studies, the rate of appearance of early leaves seems insensitive to photoperiod ( Slafer and Rawson, 1997 ) and unaffected by photoperiod insensitivity genes ( González et al , 2005 ; Ochagavía et al , 2017 ), although exceptions can be found, at least when grown in controlled conditions ( Pérez-Gianmarco et al , 2018 ). This parallelism is the main reason why the effects of daylength and/or photoperiod insensitivity genes on wheat development can frequently be estimated through their effects on FLN (e.g.…”

Wheat developmental traits as affected by the interaction betweenEps-7Dand temperature under contrasting photoperiods with insensitivePpd-D1background

“…There was a direct effect of photoperiod on time to anthesis, that was not restricted to the phase from seedling emergence to TS as the LRP was also affected by the exposure to contrasting day lengths (in line with previous evidences in the literature showing that the LRP can be highly sensitive to photoperiod; González et al, 2005bGonzález et al, , 2003Pérez-Gianmarco et al, 2018). As NILs had the insensitive allele for Ppd-D1 gene (Ppd-D1a),…”

“…However, the NILs would have sensitive alleles in the Ppd-1 loci on A and/or B genome. These genes produce responses that are frequently less noticeable than Ppd-D1, but still significant (Bentley et al, 2011;Pérez-Gianmarco et al, 2018;Shaw et al, 2013Shaw et al, , 2012. Again as expected from the literature, photoperiod effects on the rate of phenological development is not paralleled by concomitant effects on the rate of leaf initiation and therefore the final number of leaves was increased under short days (Slafer and Rawson 1994b).…”

“…which is the insensitivity gene frequently reported to have the strongest effect (e.g. Langer et al, 2014;Pérez-Gianmarco et al, 2018), we did not expect large differences between growing the plants at short or long photoperiod. However, the NILs would have sensitive alleles in the Ppd-1 loci on A and/or B genome.…”

“…Genetic factors controlling the duration of the developmental phases would be expected to have pleiotropic effect on yield traits (Börner et al, 1993;Foulkes et al, 2004). Certainly, a number of studies have shown that modifying the duration of particular developmental phases either through genetic factors (Gawroński et al, 2014;Lewis et al, 2008;Ochagavía et al, 2018a;Pérez-Gianmarco et al, 2018;Prieto et al, 2018a) or environmental treatments (González et al, 2005a(González et al, , 2003a(González et al, , 2003bSerrago et al, 2008;Steinfort et al, 2017;Wall and Cartwright, 1974) improves spike fertility; which in turn is a major determinant of wheat yield (Slafer et al, 2014;Würschum et al, 2018).…”