Temporally and Genetically Discrete Periods of Wheat Sensitivity to High Temperature.
Successive single day transfers of pot-grown wheat to high temperature (35/30°C day/night) replicated controlled environments, from the second node detectable to the milky-ripe growth stages, provides the strongest available evidence that the fertility of wheat can be highly vulnerable to heat stress during two discrete peak periods of susceptibility: early booting [decimal growth stage (GS) 41-45] and early anthesis (GS 61-65). A double Gaussian fitted simultaneously to grain number and weight data from two contrasting elite lines (Renesansa, listed in Serbia,Ppd-D1a, Rht8; Savannah, listed in UK,Ppd-D1b, Rht-D1b) identified peak periods of main stem susceptibility centered on 3 (s.e. = 0.82) and 18 (s.e. = 0.55) days (mean daily temperature = 14.3°C) pre-GS 65 for both cultivars. Severity of effect depended on genotype, growth stage and their interaction: grain set relative to that achieved at 20/15°C dropped below 80% for Savannah at booting and Renesansa at anthesis. Savannah was relatively tolerant to heat stress at anthesis. A further experiment including 62 lines of the mapping, doubled-haploid progeny of Renesansa × Savannah found tolerance at anthesis to be associated withPpd-D1b, Rht-D1b, and a QTL from Renesansa on chromosome 2A. None of the relevant markers were associated with tolerance during booting.Rht8was never associated with heat stress tolerance, a lack of effect confirmed in a further experiment whereRht8was included in a comparison of near isogenic lines in a cv. Paragon background. Some compensatory increases in mean grain weight were observed, but only when stress was applied during booting and only wherePpd-D1awas absent.
School of Agriculture, Policy and Development, University of Reading Reading, UK.
Henry M
HM
Barber
School of Agriculture, Policy and Development, University of ReadingReading, UK; Faculty of Forestry and Wood Sciences, Czech University of Life SciencesPrague, Czechia.
Martin
M
Lukac
Department of Crop Genetics, John Innes Centre Norwich, UK.
James
J
Simmonds
Computational and Systems Biology Department, Rothamsted Research Harpenden, UK.
Mikhail A
MA
Semenov
Institute of Biological, Environmental and Rural Sciences, University of Aberystwyth Aberystwyth, UK.
Mike J
MJ
Gooding
Ppd-D1; Rht; anthesis; heat stress; meiosis; wheat