J Integr Plant Biol.

• Research Articles •    

Primary root and root hair development regulation by OsAUX4 and its participation in the phosphate starvation response

Rigui Ye1,2†, Yunrong Wu1†, Zhenyu Gao3, Hao Chen1, Lixia Jia1, Dongming Li2, Xugang Li4,5, Qian Qian3*, and Yanhua Qi1,2*   

  1. 1State Key Laboratory of Plant Physiology and Biochemistry, College of ZZ Sciences, Zhejiang University, Hangzhou 310058, China
    2Key Laboratory of Herbage & Endemic Crop Biotechnology, Ministry of Education, School of Life Sciences, Inner Mongolia University, Huhehaote 010000, China
    3State Key Laboratory of Rice Biology, China National Rice Research Institute, Chinese Academy of Agricultural Sciences, Hangzhou 310006, China
    4State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai’an 271018, China
    5Sino-German Joint Research Center on Agricultural Biology, College of Life Sciences, Shandong Agricultural University, Tai’an 271018, China

    These authors contributed equally to this work.
    *Correspondences: Yanhua Qi (Rqyhjp@zju.edu.cn, Dr. Qi is fully responsible for the distributions of all materials associated with this article); Qian Qian (qianqian188@hotmail.com)
  • Received:2021-02-17 Accepted:2021-06-07 Online:2021-06-10

Abstract: Among the five members of AUX1/LAX genes coding for auxin carriers in rice, only OsAUX1 and OsAUX3 have been reported. To understand the function of the other AUX1/LAX genes, two independent alleles of osaux4 mutants, osaux4-1, and osaux4-2, were constructed using the CRISPR/Cas9 editing system. Homozygous osaux4-1 or osaux4-2 exhibited shorter primary root (PR) and longer root hair (RH) compared to the wild-type Dongjin (WT/DJ), and lost response to IAA treatment. OsAUX4 is intensively expressed in roots and localized on the plasma membrane, suggesting that OsAUX4 might function in the regulation of root development. The decreased meristem cell division activity and the downregulated expression of cell cycle genes in root apices of osaux4 mutants supported the hypothesis that OsAUX4 positively regulates PR elongation. OsAUX4 is expressed in RH, and osaux4 mutants showing longer RH compared to WT/DJ implies that OsAUX4 negatively regulates RH development. Furthermore, osaux4 mutants are insensitive to phosphate starvation (-Pi) and OsAUX4 effects on the -Pi response is associated with altered expression levels of Pi starvation regulated genes, and auxin distribution/contents. This study revealed that OsAUX4 not only regulates PR and RH development but also plays a regulatory role in crosstalk between auxin and -Pi signaling.

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