Medicago AP2-Domain Transcription Factor WRI5a Is a Master Regulator of Lipid Biosynthesis and Transfer during Mycorrhizal Symbiosis
| Autor: | Jun Yang, Yun Zhou, Wanxiao Wang, Xiaowei Zhang, Ertao Wang, Qiujin Xie, Nan Yu, Yina Jiang |
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| Rok vydání: | 2018 |
| Předmět: |
0301 basic medicine
biology fungi food and beverages ATP-binding cassette transporter Promoter Plant Science biology.organism_classification Lipids Medicago truncatula Cell biology Arbuscular mycorrhiza 03 medical and health sciences 030104 developmental biology Symbiosis Periarbuscular membrane Gene Expression Regulation Plant Lipid biosynthesis Molecular Biology Transcription factor Transcription Factors |
| Zdroj: | Molecular Plant. 11:1344-1359 |
| ISSN: | 1674-2052 |
| Popis: | Most land plants have evolved a mutualistic symbiosis with arbuscular mycorrhiza (AM) fungi that improve nutrient acquisition from the soil. In return, up to 20% of host plant photosynthate is transferred to the mycorrhizal fungus in the form of lipids and sugar. Nutrient exchange must be regulated by both partners in order to maintain a reliable symbiotic relationship. However, the mechanisms underlying the regulation of lipid transfer from the plant to the AM fungus remain elusive. Here, we show that the Medicago truncatula AP2/EREBP transcription factor WRI5a, and likely its two homologs WRI5b/Erf1 and WRI5c, are master regulators of AM symbiosis controlling lipid transfer and periarbuscular membrane formation. We found that WRI5a binds AW-box cis-regulatory elements in the promoters of M. truncatula STR, which encodes a periarbuscular membrane-localized ABC transporter required for lipid transfer from the plant to the AM fungus, and MtPT4, which encodes a phosphate transporter required for phosphate transfer from the AM fungus to the plant. The hairy roots of the M. truncatula wri5a mutant and RNAi composite plants displayed impaired arbuscule formation, whereas overexpression of WRI5a resulted in enhanced expression of STR and MtPT4, suggesting that WRI5a regulates bidirectional symbiotic nutrient exchange. Moreover, we found that WRI5a and RAM1 (Required for Arbuscular Mycorrhization symbiosis 1), which encodes a GRAS-domain transcription factor, regulate each other at the transcriptional level, forming a positive feedback loop for regulating AM symbiosis. Collectively, our data suggest a role for WRI5a in controlling bidirectional nutrient exchange and periarbuscular membrane formation via the regulation of genes involved in the biosynthesis of fatty acids and phosphate uptake in arbuscule-containing cells. |
| Databáze: | OpenAIRE |
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