1 January 2026
Min-Yao Jhu, Travis A Lee - The Plant Cell, 2026
Few sights are as emblematic of agriculture as the wheat spike—an elegant, lanceolate-shaped inflorescence that determines grain yield. The highly productive wheat spike relies on precise developmental timing; however, its architecture harbors a paradox: basal spikelets, although initiated first, are often delayed in development and remain rudimentary, failing to produce grain (Backhaus et al. 2022, 2023). The cause of this developmental imbalance has remained an open question, and understanding the gene expression patterns coordinating this crucial apical–basal axis has long been hindered by bulk tissue transcriptome approaches, obscuring regional and cellular variation.
Here, Katie A. Long, Ashleigh Lister, and colleagues (Long et al. 2025) successfully adapt multiplexed error robust fluorescence in situ hybridization (MERFISH), an imaging-based spatial transcriptomics technique (Chen et al. 2015; Moffitt et al. 2016), to the anatomically complex wheat inflorescence, providing an unprecedented, cellular-resolution view of gene activity along spikelet development. Their developmental survey spans 4 key developmental stages, including (1) the Late Double Ridge (W2.5) stage, when leaf and spikelet ridges are first visible; (2) the Lemma Primordia (W3.25), marking the initiation of glumes and lemmas; (3) the Terminal Spikelet (W4), when the uppermost spikelet forms and floral organs begin differentiating; and (4) Carpel Extension (W5), corresponding to carpel growth around the ovule. By localizing transcripts in situ for 200 developmental genes across more than 50,000 cells, the authors identified 18 distinct expression domains (EDs) and their marker genes, constructing a high-resolution map of spatiotemporal gene organization during spikelet and floral development that elucidates transcriptional signatures associated with cell type, developmental stage, and the intersection therein (Fig. 1a-c).
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