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Key Message <p>In rice, OsWRKY74 transcriptionally regulates <i>OsSWEET11</i> under low phosphorus to promote starch accumulation during grain filling, thereby contributing to yield-related traits.</p> Abstract <p>Phosphorus availability is closely associated with starch accumulation during rice grain filling, yet how phosphorus starvation signaling influences this process at the transcriptional level remains unclear. Although <i>WRKY DNA</i>-<i>BINDING PROTEIN 74</i> (<i>OsWRKY74</i>) is known to participate in low phosphorus (LP) responses at the vegetative stage, its role in reproductive development has not been fully defined. In this study, we found that OsWRKY74 is a key regulator required for maintaining starch accumulation under LP conditions. Knockout of <i>OsWRKY74</i> had little effect on plant growth compared to the wild-type (WT) under high phosphorus (HP) conditions, but significantly reduced plant height, tiller number, and grain yield per plant under LP conditions. Grain size and grain weight were also decreased in the <i>OsWRKY74</i> mutants under LP conditions. Further analyses revealed that, during grain filling, knockout of <i>OsWRKY74</i> under LP conditions impaired caryopsis development, decreased soluble sugar content, and reduced starch accumulation, compared to the WT. Mechanistically, OsWRKY74 positively regulates the expression of <i>SUGAR WILL EVENTUALLY BE EXPORTED TRANSPORTER 11</i> (<i>OsSWEET11</i>) under LP conditions. Yeast one-hybrid (Y1H), electrophoretic mobility shift assays (EMSA), and dual-luciferase (LUC) assays showed that OsWRKY74 directly binds to the&#xa0;W-box element in the <i>OsSWEET11</i> promoter and activates its transcription. Under LP conditions, <i>OsSWEET11</i> mutants exhibited defects in caryopsis development, starch accumulation, grain size, and grain weight that were highly similar to those in <i>OsWRKY74</i> mutants. Moreover, the grain traits of the <i>OsWRKY74</i>/<i>OsSWEET11</i> double mutant were comparable to those of the <i>OsSWEET11</i> single mutants. These findings demonstrate that, under LP conditions, OsWRKY74 promotes starch accumulation by regulating <i>OsSWEET11</i>, thereby contributing to the maintenance of yield-related traits. </p>

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Phosphorus starvation-responsive factor OsWRKY74 promotes starch accumulation during rice grain filling under low phosphorus conditions by regulating OsSWEET11

  • 期刊论文

  • 发表日期：

    2026年7月29日

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  • Shanshan Yang,
  • Jialin Liu,
  • Qingjie Shen,
  • Zhi Hu,
  • Yifan Li,
  • Xu Huang,
  • Mengyuan Cui,
  • Yafei Sun,
  • Surya Kant,
  • Shubin Sun

摘要

Key Message

In rice, OsWRKY74 transcriptionally regulates OsSWEET11 under low phosphorus to promote starch accumulation during grain filling, thereby contributing to yield-related traits.

Abstract

Phosphorus availability is closely associated with starch accumulation during rice grain filling, yet how phosphorus starvation signaling influences this process at the transcriptional level remains unclear. Although WRKY DNA-BINDING PROTEIN 74 (OsWRKY74) is known to participate in low phosphorus (LP) responses at the vegetative stage, its role in reproductive development has not been fully defined. In this study, we found that OsWRKY74 is a key regulator required for maintaining starch accumulation under LP conditions. Knockout of OsWRKY74 had little effect on plant growth compared to the wild-type (WT) under high phosphorus (HP) conditions, but significantly reduced plant height, tiller number, and grain yield per plant under LP conditions. Grain size and grain weight were also decreased in the OsWRKY74 mutants under LP conditions. Further analyses revealed that, during grain filling, knockout of OsWRKY74 under LP conditions impaired caryopsis development, decreased soluble sugar content, and reduced starch accumulation, compared to the WT. Mechanistically, OsWRKY74 positively regulates the expression of SUGAR WILL EVENTUALLY BE EXPORTED TRANSPORTER 11 (OsSWEET11) under LP conditions. Yeast one-hybrid (Y1H), electrophoretic mobility shift assays (EMSA), and dual-luciferase (LUC) assays showed that OsWRKY74 directly binds to the W-box element in the OsSWEET11 promoter and activates its transcription. Under LP conditions, OsSWEET11 mutants exhibited defects in caryopsis development, starch accumulation, grain size, and grain weight that were highly similar to those in OsWRKY74 mutants. Moreover, the grain traits of the OsWRKY74/OsSWEET11 double mutant were comparable to those of the OsSWEET11 single mutants. These findings demonstrate that, under LP conditions, OsWRKY74 promotes starch accumulation by regulating OsSWEET11, thereby contributing to the maintenance of yield-related traits.