Photoperiod sensitivity affects flowering duration in wheat

Abstract

SUMMARYFlowering and successful pollination in wheat are key determinants of both quantity and quality of grain. Bread wheat line 'Paragon', introgressed with single or multiple daylength insensitivity alleles was used to dissect the effects on the timing and duration of flowering within a hierarchical plant architecture. Flowering of wheat plants was observed in a series of pot-based and field experiments. Ppd-D1a was the most potent known allele affecting the timing of flowering, requiring the least thermal time to flowering across all experiments. The duration of flowering for individual lines was dominated by the shift in the start of flowering in later tillers and the number of tillers per plant, rather than variation in flowering duration of individual spikes. There was a strong relationship between flowering duration and the start of flowering with the earliest lines flowering for the longest. The greatest flowering overlap between tillers was recorded for the Ppd-1b. Across all lines, a warmer environment significantly reduced the duration of flowering and the influence of Ppd-1a alleles on the start of flowering. These findings provide evidence of pleiotropic effects of the Ppd-1a alleles, and have direct implications for breeding for increased stress resilient wheat varieties.

Temporally and Genetically Discrete Periods of Wheat Sensitivity to High Temperature

“…Photoperiod insensitivity caused by the allele Ppd-D1a , a mechanism used to avoid abiotic stress (Gomez et al, 2014), is widely considered to be a beneficial trait in future climates due to reducing thermal time to senescence (Barber et al, 2015), thereby avoiding late season heat and drought stress. It was also suggested by Jones et al (2017) that the increase in flowering duration associated with Ppd-D1a would add further resilience by increasing diversity of flowering timing within a field. However, the increase in susceptibility to heat stress associated with this allele, as well as lower overall grain yield in non-stressed seasons (Addisu et al, 2010) casts doubt over the benefits that Ppd-D1a might bring under future northern European climates.…”

“…With regards to timing of susceptibility to heat stress, the grain yields from the main stems provided better clarity than the yields from the whole plot, presumably because of the broader spectrum of the growth stages deriving from the tillers (Jones et al, 2017) and as growth stage assessments focussed primarily on main stems. On the main stems, yields of Renesansa appeared to be repeatedly compromised by day transfers to the higher temperature from 6 to 12 May, and again from 22 to 30 May (Figure 1C).…”

“…Secondly we investigate whether the effect of genotype on heat stress vulnerability interacts with timing of stress. We pay particular attention to the effects of three alleles reported to influence heat stress tolerance and have adaptive significance in wheat grown in European regions with different frequencies and severities of heat stress, namely Rht8, Ppd-D1a , and Rht-D1b (Worland, 1996; Worland et al, 1998; Rebetzke et al, 2007; Gasperini et al, 2012; Alghabari et al, 2014; Barber et al, 2015; Kowalski et al, 2016; Jones et al, 2017). We also assess associations with the 1BL/1RS translocation (Schlegel and Korzun, 1997) which introduced a number of race-specific disease resistance genes (Snape et al, 2007).…”

Observed Northward Migration of Agro‐Climate Zones in Europe Will Further Accelerate Under Climate Change

“…In the boreal agro-climatic regions an increase in ATS reflects a larger area suitable for wheat production (Peltonen-Saino, 2009). Shortened duration of flowering in the presence of mild heat stress can further increase yield losses due to shorter time for physiological escape from effects of heat stress (Jones et al, 2016, and references therein). Even though the area affected by mild heat stress in late spring (around flowering of winter wheat) has also increased, the earlier occurrence of flowering has partially compensated for negative heat stress effect, especially in continental and nemoral zones.…”

The C4 Model Grass Setaria Is a Short Day Plant with Secondary Long Day Genetic Regulation

“…This is unlike their panicoid relatives, maize and sorghum, where the tropical germplasm is the most sensitive to photoperiod, and where there has been intense selection for photoperiod insensitivity to allow for plant growth and flowering at temperate latitudes. These trends are seen in other grasses, such as maize and wheat, where there appears to be a significant shift in newer varieties to more photoperiod insensitive genotypes, as breeders strive to produce varieties that maintain yield in multiple locations (Vergara and Chang, 1985; Bentley et al, 2011; Montesino-San Martin et al, 2014; Jones et al, 2017). Breeding for photoperiod insensitivity is also a goal for millet improvement, and a detailed understanding of the effects of photoperiod on flowering time and the underlying genetic pathways that control photoperiod effects could accelerate such efforts.…”