Department of Plant Sciences, University of California, Davis, CA, 95616, USA.
Howard Hughes Medical Institute, Chevy Chase, MD, 20815, USA.
Theor Appl Genet. 2024 Oct 24;137(11):257. doi: 10.1007/s00122-024-04759-x.
Specific combinations of LFY and WAPO1 natural alleles maximize spikelet number per spike in wheat. Spikelet number per spike (SNS) is an important yield component in wheat that determines the maximum number of grains that can be formed in a wheat spike. In wheat, loss-of-function mutations in LEAFY (LFY) or its interacting protein WHEAT ORTHOLOG OF APO1 (WAPO1) significantly reduce SNS by reducing the rate of formation of spikelet meristems. In previous studies, we identified a natural amino acid change in WAPO1 (C47F) that significantly increases SNS in hexaploid wheat. In this study, we searched for natural variants in LFY that were associated with differences in SNS and detected significant effects in the LFY-B region in a nested association mapping population. We generated a large mapping population and confirmed that the LFY-B polymorphism R80S is linked with the differences in SNS, suggesting that LFY-B is the likely causal gene. A haplotype analysis revealed two amino acid changes P34L and R80S, which were both enriched during wheat domestication and breeding suggesting positive selection. We also explored the interactions between the LFY and WAPO1 natural variants for SNS using biparental populations and identified significant interaction, in which the positive effect of the 80S and 34L alleles from LFY-B was only detected in the WAPO-A1 47F background but not in the 47C background. Based on these results, we propose that the allele combination WAPO-A1-47F/LFY-B 34L 80S can be used in wheat breeding programs to maximize SNS and increase grain yield potential in wheat.
LFY 和 WAPO1 天然等位基因的特定组合可最大限度地增加小麦每穗小穗数。每穗小穗数（SNS）是小麦的一个重要产量组成部分，决定了小麦穗中可形成的最大粒数。在小麦中，LEAFY（LFY）或其互作蛋白 WHEAT ORTHOLOG OF APO1（WAPO1）的功能丧失突变通过降低小穗分生组织的形成速率而显著降低 SNS。在之前的研究中，我们在 WAPO1（C47F）中鉴定了一个天然氨基酸变化，该变化可显著增加六倍体小麦的 SNS。在这项研究中，我们在嵌套关联作图群体中搜索与 SNS 差异相关的 LFY 天然变体，并在 LFY-B 区域检测到显著影响。我们生成了一个大型作图群体，并证实 LFY-B 多态性 R80S 与 SNS 的差异相关，表明 LFY-B 是可能的因果基因。单倍型分析揭示了两个氨基酸变化 P34L 和 R80S，它们在小麦驯化和选育过程中均得到富集，表明存在正选择。我们还使用双亲种群探索了 LFY 和 WAPO1 天然变体对 SNS 的相互作用，发现了显著的相互作用，即在 WAPO-A1 47F 背景下，LFY-B 的 80S 和 34L 等位基因的正效应仅被检测到，而在 47C 背景下则未被检测到。基于这些结果，我们提出 WAPO-A1-47F/LFY-B 34L 80S 等位基因组合可用于小麦育种计划，以最大限度地提高 SNS 并增加小麦的潜在产量。
