Department of Plant Sciences, University of California, Davis, CA 95616, USA.
Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA.
Development. 2024 Aug 1;151(15). doi: 10.1242/dev.202803. Epub 2024 Jul 31.
In wheat, the transition of the inflorescence meristem to a terminal spikelet (IM→TS) determines the spikelet number per spike (SNS), an important yield component. In this study, we demonstrate that the plant-specific transcription factor LEAFY (LFY) physically and genetically interacts with WHEAT ORTHOLOG OF APO1 (WAPO1) to regulate SNS and floret development. Loss-of-function mutations in either or both genes result in significant and similar reductions in SNS, as a result of a reduction in the rate of spikelet meristem formation per day. SNS is also modulated by significant genetic interactions between LFY and the SQUAMOSA MADS-box genes VRN1 and FUL2, which promote the IM→TS transition. Single-molecule fluorescence in situ hybridization revealed a downregulation of LFY and upregulation of the SQUAMOSA MADS-box genes in the distal part of the developing spike during the IM→TS transition, supporting their opposite roles in the regulation of SNS in wheat. Concurrently, the overlap of LFY and WAPO1 transcription domains in the developing spikelets contributes to normal floret development. Understanding the genetic network regulating SNS is a necessary first step to engineer this important agronomic trait.
在小麦中，花序分生组织向顶生小穗的转变（IM→TS）决定了每穗小穗数（SNS），这是一个重要的产量组成部分。在这项研究中，我们证明植物特异性转录因子 LEAFY（LFY）与 WHEAT ORTHOLOG OF APO1（WAPO1）在物理和遗传上相互作用，以调节 SNS 和小花发育。这两个基因中的任何一个或两个基因的功能丧失突变都会导致 SNS 显著且相似的减少，这是由于每天小穗分生组织形成的速度降低所致。LFY 与 SQUAMOSA MADS-box 基因 VRN1 和 FUL2 之间的显著遗传相互作用也调节 SNS，后者促进 IM→TS 转变。单分子荧光原位杂交显示，在 IM→TS 转变过程中，发育中的小穗远端 LFY 的下调和 SQUAMOSA MADS-box 基因的上调，支持它们在小麦 SNS 调控中的相反作用。同时，LFY 和 WAPO1 转录域在发育中小穗中的重叠有助于正常小花发育。了解调节 SNS 的遗传网络是工程这一重要农艺性状的必要第一步。
