Adnan Muzaffar, Yi-Shih Chen, Hsiang-Ting Lee, Cheng-Chieh Wu, Trang Thi Le, Jin-Zhang Liang, Chun-Hsien Lu, Hariharan Balasubramaniam, Shuen-Fang Lo, Lin-Chih Yu, Chien-Hao Chan, Ku-Ting Chen, Miin-Huey Lee, Yue-Ie Hsing, Tuan-Hua David Ho, Su-May Yu

Plant Biotechnology Journal; 09 January 2024;  

https://doi.org/10.1111/pbi.14276

Summary

Root architecture and function are critical for plants to secure water and nutrient supply from the soil, but environmental stresses alter root development. The phytohormone jasmonic acid (JA) regulates plant growth and responses to wounding and other stresses, but its role in root development for adaptation to environmental challenges had not been well investigated. We discovered a novel JA Upregulated Protein 1 gene (JAUP1) that has recently evolved in rice and is specific to modern rice accessions. JAUP1 regulates a self-perpetuating feed-forward loop to activate the expression of genes involved in JA biosynthesis and signalling that confers tolerance to abiotic stresses and regulates auxin-dependent root development. Ectopic expression of JAUP1 alleviates abscisic acid- and salt-mediated suppression of lateral root (LR) growth. JAUP1 is primarily expressed in the root cap and epidermal cells (EPCs) that protect the meristematic stem cells and emerging LRs. Wound-activated JA/JAUP1 signalling promotes crosstalk between the root cap of LR and parental root EPCs, as well as induces cell wall remodelling in EPCs overlaying the emerging LR, thereby facilitating LR emergence even under ABA-suppressive conditions. Elevated expression of JAUP1 in transgenic rice or natural rice accessions enhances abiotic stress tolerance and reduces grain yield loss under a limited water supply. We reveal a hitherto unappreciated role for wound-induced JA in LR development under abiotic stress and suggest that JAUP1 can be used in biotechnology and as a molecular marker for breeding rice adapted to extreme environmental challenges and for the conservation of water resources.

See https://onlinelibrary.wiley.com/doi/full/10.1111/pbi.14276

Table 1. JAUP1 and its homologues are present only in the Oryza species with AA and BB genomes

Figure 2: JAUP1 encodes a protein containing two nuclear localization signals (NLSs). (a) Positions of the two NLSs in the JAUP1 amino acid sequence. (b) Barley aleurones transfected with Ubi:GFP-JAUP1. (c) Rice protoplasts transfected with Ubi:GFP-JAUP1 (WT or single/double NLS mutated). Scale bar = 10 μm. GFP and chloroplast red fluorescence signals were examined under confocal microscopy. Left panel: representative fluorescence images of cells. Right panel: quantification of cell numbers hosting JAUP1 in the nucleus and/or cytosol.