Posch Bradley C, Hammer Julia, Atkin Owen K, Bramley Helen, Ruan Yong-Ling, Trethowan Richard, Coast Onoriode
ARC Centre of Excellence in Plant Energy Biology, Division of Plant Sciences, Research School of Biology, The Australian National University, Canberra, ACT, Australia.
Department of Biology, The University of Western Ontario, 1151 Richmond St, N6A 3K7, London, Canada.
J Exp Bot. 2022 May 23;73(10):3268-82. doi: 10.1093/jxb/erac039.
Wheat photosynthetic heat tolerance can be characterized using minimal chlorophyll fluorescence to quantify the critical temperature (Tcrit) above which incipient damage to the photosynthetic machinery occurs. We investigated intraspecies variation and plasticity of wheat Tcrit under elevated temperature in field and controlled-environment experiments, and assessed whether intraspecies variation mirrored interspecific patterns of global heat tolerance. In the field, wheat Tcrit varied diurnally-declining from noon through to sunrise-and increased with phenological development. Under controlled conditions, heat stress (36 °C) drove a rapid (within 2 h) rise in Tcrit that peaked after 3-4 d. The peak in Tcrit indicated an upper limit to PSII heat tolerance. A global dataset [comprising 183 Triticum and wild wheat (Aegilops) species] generated from the current study and a systematic literature review showed that wheat leaf Tcrit varied by up to 20 °C (roughly two-thirds of reported global plant interspecies variation). However, unlike global patterns of interspecies Tcrit variation that have been linked to latitude of genotype origin, intraspecific variation in wheat Tcrit was unrelated to that. Overall, the observed genotypic variation and plasticity of wheat Tcrit suggest that this trait could be useful in high-throughput phenotyping of wheat photosynthetic heat tolerance.
小麦的光合耐热性可以通过最小叶绿素荧光来表征，以量化光合机构开始受到损伤时的临界温度（Tcrit）。我们在田间和控制环境实验中研究了高温下小麦Tcrit的种内变异和可塑性，并评估了种内变异是否反映了全球耐热性的种间模式。在田间，小麦Tcrit呈昼夜变化——从中午到日出逐渐下降——并随着物候发育而增加。在控制条件下，热胁迫（36°C）导致Tcrit迅速（在2小时内）上升，并在3-4天后达到峰值。Tcrit的峰值表明了PSII耐热性的上限。由本研究和系统文献综述生成的一个全球数据集（包含183个小麦属和野生小麦物种）表明，小麦叶片Tcrit的变化幅度高达20°C（约占已报道的全球植物种间变异的三分之二）。然而，与已与基因型起源纬度相关的全球种间Tcrit变异模式不同，小麦Tcrit的种内变异与之无关。总体而言，观察到的小麦Tcrit的基因型变异和可塑性表明，该性状可能有助于小麦光合耐热性的高通量表型分析。
