2. Academic Validation
  3. Natural variation in the ORL4 promoter regulates rice leaf rolling to modulate leaf architecture and yield

Natural variation in the ORL4 promoter regulates rice leaf rolling to modulate leaf architecture and yield

  • Plant Cell. 2026 Apr 3;38(4):koag086. doi: 10.1093/plcell/koag086.
Xianpeng Wang 1,  Bingxia Xu 1,  Qianfeng Hu 1,  Yong Zhao 1,  Quan Zhang 1 2,  Honglin Li 1,  Zhiqi Ma 1,  Penghui Xu 1,  Lingling Ma 1,  Zhenyuan Wu 1,  Xuehan Qian 1,  Jinlong Li 1,  Jinyue Yang 1,  Ruiqi Liu 1,  Wensheng Wang 3,  Jianlong Xu 3,  Junzhou Li 4,  Lei Chen 5,  Yinghua Pan 5,  Xingming Sun 1 6,  Jinjie Li 1 6,  Hongliang Zhang 1 6,  Zichao Li 1 6,  Zhanying Zhang 1 6
Affiliations

Affiliations

  • 1 Frontiers Science Center for Molecular Design Breeding, Key Laboratory of Crop Heterosis and Utilization (MOE), Beijing Key Laboratory of Crop Genetic Improvement, College of Agronomy and Biotechnology, China Agricultural University, Beijing 100193, China.
  • 2 Beijing Vegetable Research Center, Beijing Academy of Agriculture and Forestry Science, Beijing 100097, China.
  • 3 Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing 10081, China.
  • 4 Henan Key Laboratory of Rice Molecular Breeding and High Efficiency Production, College of Agronomy, Henan Agricultural University, Zhengzhou 450046, China.
  • 5 Guangxi Key Laboratory of Rice Genetics and Breeding, Rice Research Institute of Guangxi Academy of Agricultural Sciences, Nanning, Guangxi, China.
  • 6 Sanya Institute of China Agricultural University, Sanya 572025, China.
PMID: 41871429 DOI: 10.1093/plcell/koag086
Abstract

Rice (Oryza sativa L.) leaf rolling enhances canopy architecture and photosynthetic efficiency, thereby improving yield potential. Through genome-wide association studies (GWAS) of 802 Xian and Geng rice accessions, we identified 32 loci associated with the leaf rolling index (LRI) and characterized OUTWARD ROLLED LEAF 4 (ORL4) as a regulatory gene from natural germplasm. CRISPR/Cas9-mediated knockout of ORL4 resulted in abaxially rolled leaves, driven by excessive bulliform cell proliferation and disrupted vascular patterning. A promoter variant (Chr04_19562737-C/T) modulates ORL4 expression by altering the binding affinity of the transcription factor RICE OUTERMOST CELL-SPECIFIC 8 (ROC8). Carriers of the ORL4C allele exhibit stronger ROC8 binding, higher ORL4 expression, and adaxially rolled or flat leaves; ORL4T carriers show the opposite phenotype. ORL4 forms a ternary complex with ROC8 and TOPLESS-RELATED PROTEIN 2(TPL2) to suppress ABAXIALLY CURLED LEAF 1(ACL1), a positive regulator of bulliform cell differentiation. Evolutionary analyses indicated that the ORL4C and ORL4T alleles originated from Oryza nivara and Oryza rufipogon, with ORL4C favored in Geng and ORL4T in Xian during domestication. Promoter editing of ORL4 in the elite cultivar "Shennong 89-366" generated lines with enhanced LRI, achieving a significant yield increase in field trials. This study elucidates the genetic and molecular basis of leaf rolling and provides a promising strategy for rice yield improvement via precise promoter editing.

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