Mutation of OUR1/OsbZIP1, which encodes a member of the basic leucine zipper transcription factor family, promotes root development in rice through repressing auxin signaling

• Published in: Plant science (Limerick) Vol. 306; p. 110861
• Main Authors: Hasegawa, Tomomi, Lucob-Agustin, Nonawin, Yasufuku, Koki, Kojima, Takaaki, Nishiuchi, Shunsaku, Ogawa, Atsushi, Takahashi-Nosaka, Misuzu, Kano-Nakata, Mana, Inari-Ikeda, Mayuko, Sato, Moeko, Tsuji, Hiroyuki, Wainaina, Cornelius Mbathi, Yamauchi, Akira, Inukai, Yoshiaki
• Format: Journal Article
• Language: English
• Published: Ireland Elsevier B.V 01.05.2021
• Subjects: Auxin signaling; Basic-Leucine Zipper Transcription Factors - genetics; Basic-Leucine Zipper Transcription Factors - metabolism; Biological Transport - drug effects; bZIP transcription factor; Gene Expression Regulation, Plant - drug effects; Genes, Plant; Genetic Variation; Genotype; Indoleacetic Acids - metabolism; Mutant; Mutation; Organogenesis, Plant - drug effects; Oryza - genetics; Oryza - growth & development; Oryza - metabolism; Phenotype; Plant Roots - genetics; Plant Roots - growth & development; Plant Roots - metabolism; Promoter Regions, Genetic - drug effects; Rice; Root development; Root system architecture; Signal Transduction - drug effects; Signal Transduction - genetics; Auxin signaling; bZIP transcription factor; Root development; Mutant; Root system architecture; Rice
• ISSN: 0168-9452; 1873-2259
• DOI: 10.1016/j.plantsci.2021.110861

•We identified and characterized a rice mutant, outstanding rooting1 (our1) that exhibited a developed root system.•The OUR1 gene encodes OsbZIP1, a member of the basic leucine zipper transcription factor family.•The our1 gene promotes root development by suppressing auxin signaling, which may be key for improving root architecture. A well-developed root system is essential for efficient water uptake, particularly in drought-prone environments. However, the molecular mechanisms underlying the promotion of root development are poorly understood. We identified and characterized a rice mutant, outstanding rooting1 (our1), which exhibited a well-developed root system. The our1 mutant displayed typical auxin-related phenotypes, including elongated seminal root and defective gravitropism. Seminal root elongation in the our1 mutant was accelerated via the promotion of cell division and elongation. In addition, compared with the wild type, the density of short and thin lateral roots (S-type LRs) was reduced in the our1 mutant, whereas that of long and thick LRs (L-type LRs) was increased. Expression of OUR1, which encodes OsbZIP1, a member of the basic leucine zipper transcription factor family, was observed in the seminal root tip and sites of LR emergence, wherein attenuation of reporter gene expression levels controlled by the auxin response promoter DR5 was also observed in the our1 mutant. Taken together, our results indicate that the our1 gene promotes root development by suppressing auxin signaling, which may be a key factor contributing to an improvement in root architecture.