J Integr Plant Biol. ›› 2023, Vol. 65 ›› Issue (3): 772-790.DOI: 10.1111/jipb.13408

• Functional Omics and Systems Biology • Previous Articles     Next Articles

Positional cloning and characterization reveal the role of a miRNA precursor gene ZmLRT in the regulation of lateral root number and drought tolerance in maize

Ming Zhang1†, Yanhong Chen1,2†, Hongyan Xing1,3†, Wensheng Ke1, Yunlu Shi4, Zhipeng Sui1,5, Ruibin Xu1,6, Lulu Gao1, Ganggang Guo1,3, Jiansheng Li7, Jiewen Xing1* and Yirong Zhang1,7*   

  1. 1. State Key Laboratory for Agrobiotechnology, Key Laboratory of Crop Heterosis and Utilization (MOE), Key Laboratory of Crop Genetic Improvement, China Agricultural University, Beijing 100193, China;
    2. Agronomy College of Shandong Agricultural University, Taian 271018, China;
    3. Key Laboratory of Crop Germplasm Resources and Utilization (MARA), Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing 100081, China;
    4. Center for Crop Functional Genomics and Molecular Breeding, China Agricultural University, Beijing 100193, China;
    5. Yantai Science and Technology Innovation Promotion Center, Yantai 264003, China;
    6. Beijing Key Laboratory of Maize DNA Fingerprinting and Molecular Breeding, Maize Research Institute, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100097, China;
    7. National Maize Improvement Center of China, China Agricultural University, Beijing 100193, China
    These authors contributed equally to this work.
    *Correspondences: Yirong Zhang (zhangyr@cau.edu.cn); Jiewen Xing (jiewen.xing@cau.edu.cn, Dr. Xing is responsible for the distribution of the materials associated with this article)
  • Received:2022-10-05 Accepted:2022-11-09 Online:2022-11-10 Published:2023-03-01

Abstract: Lateral roots play essential roles in drought tolerance in maize (Zea mays L.). However, the genetic basis for the variation in the number of lateral roots in maize remains elusive. Here, we identified a major quantitative trait locus (QTL), qLRT5-1, controlling lateral root number using a recombinant inbred population from a cross between the maize lines Zong3 (with many lateral roots) and 87-1 (with few lateral roots). Fine-mapping and functional analysis determined that the candidate gene for qLRT5-1, ZmLRT, expresses the primary transcript for the microRNA miR166a. ZmLRT was highly expressed in root tips and lateral root primordia, and knockout and overexpression of ZmLRT increased and decreased lateral root number, respectively. Compared with 87-1, the ZmLRT gene model of Zong3 lacked the second and third exons and contained a 14 bp deletion at the junction between the first exon and intron, which altered the splicing site. In addition, ZmLRT expression was significantly lower in Zong3 than in 87-1, which might be attributed to the insertions of a transposon and over large DNA fragments in the Zong3 ZmLRT promoter region. These mutations decreased the abundance of mature miR166a in Zong3, resulting in increased lateral roots at the seedling stage. Furthermore, miR166a post-transcriptionally repressed five development-related class-III homeodomain-leucine zipper genes. Moreover, knockout of ZmLRT enhanced drought tolerance of maize seedlings. Our study furthers our understanding of the genetic basis of lateral root number variation in maize and highlights ZmLRT as a target for improving drought tolerance in maize.

Key words: drought tolerance, lateral root number, maize, miRNA precursor, QTL mapping

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