Researchers reveal influence of brassinosteroid and sugar signaling on regulation of wheat grain size.

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TabHLH489 and TaSnRK1α1 integrate BR and sugar signals to control wheat grain length. Credit: Xiao Jun

Grain size plays a central role in determining wheat yield, and precise regulation of grain growth has emerged as an important strategy for increasing yields in many major crops such as rice and maize. However, the genetic basis and potential molecular regulatory mechanisms controlling important aspects of wheat grain development remain elusive, hindering the quest to increase wheat yield.

In a recent collaboration Study published in plant biotechnologyResearchers led by Professor Xiao Jun of the Institute of Genetics and Developmental Biology of the Chinese Academy of Sciences, together with Professor Bai Mingyi of Shandong University, have identified a gene module that controls grain length in wheat, providing new insights. Is available. The interplay between brassinosteroid (BR) and sugar signals influences grain size.

The researchers used a combination of genome-wide association studies and linkage analysis to pinpoint an unusual helix-loop-helix transcription factor, TabHLH489-D1, that correlates significantly with grain length in wheat. TabHLH489-D1 and its homologous genes were found to reduce both grain length and thousand grain weight.

They revealed that TaSnRK1α1 facilitates the degradation of TabHLH489 through phosphorylation, thereby promoting the expansion of seed coat cells during the early stages of wheat grain development. Sugar, in turn, induces the accumulation of TaSnRK1α1 protein, which further enhances the degradation of TabHLH489 and collectively regulates wheat grain growth.

Furthermore, TabHLH489 was found to be a negative regulator of the plant hormone BR, and knockout of TabHLH489 increased BR sensitivity in wheat. In wheat mutants with overexpression of the BR receptor Tabzr1 and the BR-negative regulator kinase TaSK2, increased expression of TabHLH489 expression is associated with smaller wheat grains and reduced thousand-grain weight.

In contrast, in TaSK2 knockout mutants and plants with overexpressed TaBZR1, reduction of TabHLH489 expression results in longer wheat grains and increased thousand-grain weight.

Specifically, TaBZR1 directly interacts with the TabHLH489 promoter and exerts repressive effects on its expression. Natural variation in the TabHLH489-D1 promoter region affected TaBZR1 binding, decreased TabHLH489-D1 expression, and resulted in increased grain length.

This study successfully cloned the key gene TabHLH489 and elucidated its role in regulating wheat grain length. The identification of a gene functional module that controls wheat grain size and the elucidation of the regulatory mechanisms of BR and sugar on TabHLH489 at both transcriptional and protein levels is an important milestone.

The results not only provide important theoretical support, but also provide valuable allelic gene resources for future wheat breeding efforts.

more information:
Jinyang Lyu et al., The TaSnRK1‐TabHLH489 module integrates brassinosteroid and sugar signaling to regulate grain length in bread wheat. Plant Biotechnology Journal (2024). DOI: 10.1111/pbi.14319

Awarded by the Chinese Academy of Sciences


Citation: Researchers reveal impact of brassinosteroid and sugar signaling on wheat grain size regulation (2024, March 29) Accessed March 29, 2024 https://phys.org/news/2024-03-reveal-impact-brassinosteroid-sugar Retrieved from -wheat.html.

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