Parrado Jorge D, Savin Roxana, Slafer Gustavo A
Department of Agricultural and Forest Sciences and Engineering, University of Lleida-AGROTECNIO-CERCA Center, Av. Rovira Roure 191, 25198 Lleida, Spain.
ICREA, Catalonian Institution for Research and Advanced Studies, Spain.
J Exp Bot. 2025 Apr 9;76(6):1691-1703. doi: 10.1093/jxb/erae492.
The photoperiod-insensitive allele of Photoperiod-H1 (ppd-H1) increases spike fertility in barley, both indirectly by lengthening flowering time and directly when flowering time is accelerated under extra long photoperiods. To determine if the effect of PPD-H1 on spike fertility is related to the initiation or the mortality of spikelets/florets, we performed detailed analysis of the dynamics of floret development along the barley spikes. Four near-isogenic lines (NILs) combining ppd-H1 and Ppd-H1 alleles with two PHYTOCHROME C (PhyC-l and PhyC-e) backgrounds were compared under 12 h and 24 h photoperiods. The ppd-H1 line consistently showed higher survival rates of floret primordia. Fertility differences were observed within spikes, with the insensitive ppd-H1 line improving fertility in the less favoured distal florets, and even inducing more developmental progress before floret mortality in apical spikelets. The ppd-H1 allele constitutively enhanced floret primordia survival, as the effect was seen even under long photoperiods when lines had similar phenology. The dynamics of floret development affecting spike fertility resulted in a parallel effect on grain setting. Together, these results indicate that photoperiod insensitivity in barley contributes to greater yield potential by reducing floret primordia mortality and improving spike fertility.
光周期- H1（ppd - H1）的光周期不敏感等位基因可提高大麦的穗结实率，一方面通过延长开花时间间接实现，另一方面在超长光周期下加速开花时间时直接实现。为了确定PPD - H1对穗结实率的影响是否与小穗/小花的起始或死亡率有关，我们对沿大麦穗的小花发育动态进行了详细分析。在12小时和24小时光周期条件下，比较了四个将ppd - H1和Ppd - H1等位基因与两种光敏色素C（PhyC - l和PhyC - e）背景相结合的近等基因系（NILs）。携带ppd - H1的品系始终表现出较高的小花原基存活率。在穗内观察到结实率差异，光周期不敏感的ppd - H1品系提高了不太有利的远端小花的结实率，甚至在顶端小穗的小花死亡前诱导了更多的发育进程。ppd - H1等位基因组成性地增强小花原基存活，因为即使在光周期较长且品系物候相似的情况下也能观察到这种效应。影响穗结实率的小花发育动态对籽粒结实产生了类似的影响。总之，这些结果表明，大麦中的光周期不敏感性通过降低小花原基死亡率和提高穗结实率，有助于提高产量潜力。
