Involvement of auxin in the regulation of ammonium tolerance in rice (Oryza sativa L.)
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Background and aims
Ammonium (NH4+) is an important nitrogen source and is widely used as a fertilizer in agricultural systems. However, excess NH4+ inhibits root growth, and, subsequently, vegetative shoot growth and yield. This study examines whether auxin is involved in differential NH4+ tolerance in rice (Oryza sativa L.), and how auxin is regulated under high-NH4+ conditions in rice.
An NH4+-sensitive (Kasalath, Kas) and an NH4+-insensitive (Koshihikari, Kos) rive cultivar were cultured hydroponically with or without exogenous indole-3-acetic acid (IAA) and auxin biosynthesis inhibitors. Root growth, root area, tissue IAA content, and transcription of genes involved in auxin biosynthesis, conjugation and degradation were determined.
pDR5::GUS staining and auxin measurement show that high NH4+ can decrease free IAA content in roots. In addition, quantitative RT-PCR, pharmacology, and genetics analysis suggest that Kos possesses a higher capacity for auxin biosynthesis and a weaker capacity for auxin metabolism compared to Kas under high-NH4+ stress.
We conclude that the NH4+-tolerant cultivar possesses a higher capacity to maintain auxin homeostasis under high-NH4+ stress, and that this advantage is incurred by promotion of auxin biosynthesis and a suppression of auxin metabolism.
KeywordsAmmonium toxicity Auxin level Nitrogen fertilizer Rice Root development
Dioxygenase for Auxin Oxidation
Group II GRETCHEN HAGEN3 acyl amido synthetases
TRYPTOPHAN AMINOTRANSFERASE RELATED
5-(4-chlorophenyl)-4H-1, 2, 4-triazole-3-thiol
We thank Prof. Shiping Wang (Huazhong Agricultural University) and Prof. Jianmin Wan (Nanjing Agricultural University) for kindly providing the OsGH3.2ox and Osdao mutant, respectively. This work was supported by grants from the National Natural Science Foundation of China [31430095, 31601823 and 31471948.], China Postdoctoral Science Foundation [2015 M58048 and 2017 T100411] and the University of Melbourne.
- Barth C, Gouzd ZA, Steele HP, Imperio RM (2010) A mutation in GDP-mannose pyrophosphorylase causes conditional hypersensitivity to ammonium, resulting in Arabidopsis root growth inhibition, altered ammonium metabolism, and hormone homeostasis. J Exp Bot 61:379–394. https://doi.org/10.1093/jxb/erp310 CrossRefPubMedGoogle Scholar
- Ding ZJ, Yan JY, Li CX, Li GX, Wu YR, Zheng SJ (2015) Transcription factor WRKY46 modulates the development of Arabidopsis lateral roots in osmotic/salt stress conditions via regulation of ABA signaling and auxin homeostasis. Plant J 84:56–69. https://doi.org/10.1111/tpj.12958 CrossRefPubMedGoogle Scholar
- Esteban R, Royo B, Urarte E, Zamarreno AM, Garcia-Mina JM, Moran JF (2016b) Both free indole-3-acetic acid and photosynthetic performance are important players in the response of Medicago truncatula to urea and ammonium nutrition under axenic conditions. Front Plant Sci 7:140. https://doi.org/10.3389/fpls.2016.00140 CrossRefPubMedPubMedCentralGoogle Scholar
- Kakei Y et al (2017) Biochemical and chemical biology study of rice OsTAR1 revealed that tryptophan aminotransferase is involved in auxin biosynthesis: identification of a potent OsTAR1 inhibitor, Pyruvamine 2031. Plant Cell Physiol 58:598–606. https://doi.org/10.1093/pcp/pcx007 CrossRefPubMedGoogle Scholar
- Li XZ, Yang DL, Sun L, Li Q, Mao BZ, He ZH (2016) The systemic acquired resistance regulator OsNPR1 attenuates growth by repressing auxin signaling through promoting IAA-amido synthase expression. Plant Physiol 172:546–558. https://doi.org/10.1104/pp.16.00129 CrossRefPubMedPubMedCentralGoogle Scholar
- Liu Y, Lai NW, Gao K, Chen FJ, Yuan LX, Mi GH (2013) Ammonium inhibits primary root growth by reducing the length of meristem and elongation zone and decreasing elemental expansion rate in the root apex in Arabidopsis thaliana. PLoS One 8:e61031. https://doi.org/10.1371/journal.pone.0061031 CrossRefPubMedPubMedCentralGoogle Scholar
- Luo XT, Cai BD, Chen X, Feng YQ (2017) Improved methodology for analysis of multiple phytohormones using sequential magnetic solid-phase extraction coupled with liquid chromatography-tandem mass spectrometry. Anal Chim Acta 983:112–120. https://doi.org/10.1016/j.aca.2017.06.019 CrossRefPubMedGoogle Scholar
- Qin H, Zhang ZJ, Wang J, Chen XB, Wei PC, Huang RF (2017) The activation of OsEIL1 on YUC8M transcription and auxin biosynthesis is required for ethylene-inhibited root elongation in rice early seedling development. PLoS Genet 13:e1006955. https://doi.org/10.1371/journal.pgen.1006955 CrossRefPubMedPubMedCentralGoogle Scholar
- Raven JA, Wollenweber B, Handley LL (1993) The quantitative role of ammonia/ammonium transport and metabolism by plants in the global nitrogen cycle. Physiol Plant 89:512–518. https://doi.org/10.1111/j.1399-3054.1993.tb05207.x CrossRefGoogle Scholar
- Siddiqi MY, Malhotra B, Min XJ, Glass ADM (2002) Effects of ammonium and inorganic carbon enrichment on growth and yield of a hydroponic tomato crop. J Plant Nutr Soil Sci 165:191–197. https://doi.org/10.1002/1522-2624(200204)165:23.0.CO;2-D CrossRefGoogle Scholar
- Yang ZB, Geng XY, He CM, Zhang F, Wang R, Horst WJ, Ding ZJ (2014) TAA1-regulated local auxin biosynthesis in the root-apex transition zone mediates the aluminum-induced inhibition of root growth in Arabidopsis. Plant Cell 26:2889–2904. https://doi.org/10.1105/tpc.114.127993 CrossRefPubMedPubMedCentralGoogle Scholar