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Kojima M, Makita N, Miyata K, Yoshino M, Iwase A, Ohashi M, Surjana A, Kudo T, Takeda-Kamiya N, Toyooka K, Miyao A, Hirochika H, Ando T, Shomura A, Yano M, Yamamoto T, Hobo T, Sakakibara H. A cell wall-localized cytokinin/purine riboside nucleosidase is involved in apoplastic cytokinin metabolism in Oryza sativa. Proc Natl Acad Sci U S A 2023; 120:e2217708120. [PMID: 37639600 PMCID: PMC10483608 DOI: 10.1073/pnas.2217708120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Accepted: 07/18/2023] [Indexed: 08/31/2023] Open
Abstract
In the final step of cytokinin biosynthesis, the main pathway is the elimination of a ribose-phosphate moiety from the cytokinin nucleotide precursor by phosphoribohydrolase, an enzyme encoded by a gene named LONELY GUY (LOG). This reaction accounts for most of the cytokinin supply needed for regulating plant growth and development. In contrast, the LOG-independent pathway, in which dephosphorylation and deribosylation sequentially occur, is also thought to play a role in cytokinin biosynthesis, but the gene entity and physiological contribution have been elusive. In this study, we profiled the phytohormone content of chromosome segment substitution lines of Oryza sativa and searched for genes affecting the endogenous levels of cytokinin ribosides by quantitative trait loci analysis. Our approach identified a gene encoding an enzyme that catalyzes the deribosylation of cytokinin nucleoside precursors and other purine nucleosides. The cytokinin/purine riboside nucleosidase 1 (CPN1) we identified is a cell wall-localized protein. Loss-of-function mutations (cpn1) were created by inserting a Tos17-retrotransposon that altered the cytokinin composition in seedling shoots and leaf apoplastic fluid. The cpn1 mutation also abolished cytokinin riboside nucleosidase activity in leaf extracts and attenuated the trans-zeatin riboside-responsive expression of cytokinin marker genes. Grain yield of the mutants declined due to altered panicle morphology under field-grown conditions. These results suggest that the cell wall-localized LOG-independent cytokinin activating pathway catalyzed by CPN1 plays a role in cytokinin control of rice growth. Our finding broadens our spatial perspective of the cytokinin metabolic system.
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Affiliation(s)
- Mikiko Kojima
- Graduate School of Bioagricultural Sciences, Nagoya University, Chikusa, Nagoya464-8601, Japan
- RIKEN Center for Sustainable Resource Science, Tsurumi, Yokohama230-0045, Japan
| | - Nobue Makita
- RIKEN Center for Sustainable Resource Science, Tsurumi, Yokohama230-0045, Japan
| | - Kazuki Miyata
- Graduate School of Bioagricultural Sciences, Nagoya University, Chikusa, Nagoya464-8601, Japan
| | - Mika Yoshino
- Graduate School of Bioagricultural Sciences, Nagoya University, Chikusa, Nagoya464-8601, Japan
| | - Akira Iwase
- RIKEN Center for Sustainable Resource Science, Tsurumi, Yokohama230-0045, Japan
| | - Miwa Ohashi
- Graduate School of Bioagricultural Sciences, Nagoya University, Chikusa, Nagoya464-8601, Japan
| | - Alicia Surjana
- Graduate School of Bioagricultural Sciences, Nagoya University, Chikusa, Nagoya464-8601, Japan
| | - Toru Kudo
- RIKEN Center for Sustainable Resource Science, Tsurumi, Yokohama230-0045, Japan
| | | | - Kiminori Toyooka
- RIKEN Center for Sustainable Resource Science, Tsurumi, Yokohama230-0045, Japan
| | - Akio Miyao
- National Institute of Agrobiological Sciences, Tsukuba305-8602, Japan
- Institute of Crop Science, National Agricultural and Food Research Organization, Tsukuba305-8518, Japan
| | | | - Tsuyu Ando
- National Institute of Agrobiological Sciences, Tsukuba305-8602, Japan
- Institute of Crop Science, National Agricultural and Food Research Organization, Tsukuba305-8518, Japan
- Institute of Society for Techno-innovation of Agriculture, Forestry and Fisheries, Tsukuba, Ibaraki305-0854, Japan
| | - Ayahiko Shomura
- National Institute of Agrobiological Sciences, Tsukuba305-8602, Japan
- Institute of Crop Science, National Agricultural and Food Research Organization, Tsukuba305-8518, Japan
- Institute of Society for Techno-innovation of Agriculture, Forestry and Fisheries, Tsukuba, Ibaraki305-0854, Japan
| | - Masahiro Yano
- National Institute of Agrobiological Sciences, Tsukuba305-8602, Japan
- Institute of Crop Science, National Agricultural and Food Research Organization, Tsukuba305-8518, Japan
| | - Toshio Yamamoto
- National Institute of Agrobiological Sciences, Tsukuba305-8602, Japan
- Institute of Crop Science, National Agricultural and Food Research Organization, Tsukuba305-8518, Japan
- Institute of Plant Science and Resources, Okayama University, Kurashiki710-0046, Japan
| | - Tokunori Hobo
- Bioscience and Biotechnology Center, Nagoya University, Chikusa, Nagoya464-8601, Japan
| | - Hitoshi Sakakibara
- Graduate School of Bioagricultural Sciences, Nagoya University, Chikusa, Nagoya464-8601, Japan
- RIKEN Center for Sustainable Resource Science, Tsurumi, Yokohama230-0045, Japan
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