The miR156h-TaSPL4-TaPIN18 Module Regulates Plant Architecture and Grain Size by Modulating Auxin Transport in Wheat.

Overexpression of miR156h in wheat reduces leaf, spikelet, and grain size while increasing tillering and compact architecture, linked to direct suppression of TaSPL4 and altered auxin transport.

• Why it matters: Wheat yield depends on plant architecture and grain traits, but the miR156-SPL regulatory logic in wheat is not fully defined, limiting molecular breeding targets.
• What they did: The study combined miR156h overexpression, CRISPR/Cas9 knockout of TaSPL4, and TaSPL4 overexpression, plus identification of TaPIN18 as a downstream gene affecting auxin transport and distribution.
• The result: TaSPL4 knockout increases tiller number and compact growth with reduced grain width and thousand-grain weight, while TaSPL4 overexpression enhances grain length, grain width, and thousand-grain weight via TaPIN18-mediated auxin transport.

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