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Arbuscular mycorrhiza improves plant adaptation to phosphorus deficiency through regulating the expression of genes relevant to carbon and phosphorus metabolism
Li-Jiao XU, Xue-Lian JIANG, Zhi-Peng HAO, Tao LI, Zhao-Xiang WU, Bao-Dong CHEN
Chin J Plant Ecol    2017, 41 (8): 815-825.   DOI: 10.17521/cjpe.2017.0018
Abstract   (1987 HTML170 PDF(pc) (2693KB)(1354)  

Aims Arbuscular mycorrhizal (AM) symbiosis plays an important role in plant adaptation to phosphorus (P) deficiency. The mycorrhizal fungi can directly regulate P stress response of the host plants, and can also indirectly influence neighbor plants via AM exudates. This study aimed to reveal the regulation mechanisms of plant response to P deficiency by AM associations. Methods In a compartmentation cultivation experiment with Zea mays ‘B73’ and AM fungus Rhizophagus irregularis ‘DAOM197198’, we investigated mycorrhizal effects on plant P nutrition and the expression of plant and fungal genes related to P and carbon (C) metabolisms under both low P (10 mg?kg-1) and high P (100 mg?kg-1) conditions. The cultivation system consisted of three compartments, namely donor compartment, buffer compartment and receiver compartment divided by two pieces of microporous filters with pore size of 0.45 μm. Maize plant in donor compartment inoculated with AM fungus served as a source of AM exudates. The microporous filters could restrict the development of extraradical mycelium of AM fungi, but allow diffusion of AM exudates. Real-time PCR was performed to quantify the gene expression levels both in maize plants and AM fungi. Important findings The experimental results indicated that under low P conditions mycorrhizal colonization increased plant dry weight and P concentration in donor plants, and up-regulated plant genes encoding P transporters Pht1;2, Pht1;6, phosphoenolpiruvate carboxylase (PEPC), inorganic pyrophosphatase (TC289), glycerol-3-phosphate transporter (G3PT) and malate synthase (MAS1). The expression of AM fungal genes encoding P transporter (GiPT), GlcNAc transporter (NGT1), GlcNAc kinase (HXK1b), GlcNAc phosphomutase (AGM1), UDP GlcNAc pyrophosphorylase (UAP1), chitin synthase (CHS1), GlcNAc-6-phosphate deacetylase (DAC1) and glucosamine-6-phosphate isomerase (NAG1) was significantly higher under low P conditions compared with high P conditions. However, for the receiver plants, plant dry mass and P concentration were only significantly increased by higher P addition, while inoculation treatment significantly up-regulated the expression of P transporter genes Pht1;2 and Pht1;6, C metabolism related genes G3PT, PEPC, TC289 and MAS1. The study proved that AM exudates could potentially stimulate plant response to P deficiency by regulating functional genes relevant to P and C metabolisms in the mycorrhizal associations.


地上部干质量
Shoot dry mass
根系干质量
Root dry mass
地上部磷浓度
Shoot P concentration
根系磷浓度
Root P concentration
Pht1;2 Pht1;6 G3PT PEPC TC289 MAS1
供体植物 Donor
接种处理 Inoculation treatment (I) * ** * ** ** ** ** ** ns **
磷水平 P levels (P) ** ns ** ** ** ** ** ** ** ns
交互作用 I × P ** ** ns * ** ** ** ** ns **
受体植物 Receiver
接种处理 Inoculation treatment (I) ns ns ns ns ** ** ** ** ** **
磷水平 P levels (P) * * * * ** ** ** ** ** **
交互作用 I × P ns ns ns ns ns ** ** ** ** **
Appendix III Two-way ANOVA of shoot and root dry mass, P concentrations and expression of genes related to C and P metabolisms as influenced by mycorrhizal inoculation and soil P levels
Extracts from the Article
丛枝菌根(AM)共生体系对于植物适应低磷胁迫具有重要作用。AM不仅直接调节宿主植物对低磷胁迫的响应, 还可能通过分泌物影响相邻的非菌根植物。该研究采用分室培养系统, 以玉米(Zea mays)和AM真菌Rhizophagus irregularis为试验材料, 考察低磷(10 mg·kg-1)和高磷(100 mg·kg-1)条件下, 菌根共生体系对植物生长、磷营养以及碳磷代谢相关基因表达的影响, 以揭示AM调节植物低磷胁迫响应的生理机制。分室培养系统由0.45 μm微孔滤膜分隔成供体室、缓冲室和受体室3个分室, 以供体室菌根化植物为AM分泌物来源, 通过微孔膜阻止菌根真菌对未接种受体植物的直接影响, 但允许AM分泌物在分室间的扩散。采用实时荧光定量PCR技术分析玉米以及AM真菌自身碳磷代谢相关基因的表达情况。试验结果表明, 低磷条件下接种AM真菌显著提高了供体植物干质量和磷浓度, 上调了玉米碳磷代谢相关基因的表达。AM真菌磷转运蛋白基因和碳代谢相关基因在低磷条件下的表达水平显著高于高磷水平; 对于受体植物而言, 仅高磷处理显著提高了玉米植株干质量和磷含量, 而接种处理显著上调了受体植物磷转运蛋白基因和碳代谢相关基因的表达水平。该研究表明, 低磷胁迫下AM可能通过分泌物调控植物碳磷代谢相关基因的表达, 进而调节植物对低磷胁迫的生理响应。
徐丽娇, 姜雪莲, 郝志鹏, 李涛, 吴照祥, 陈保冬. 丛枝菌根通过调节碳磷代谢相关基因的表达增强植物对低磷胁迫的适应性. 植物生态学报, 2017, 41(8):815-825 https://doi.org/10.17521/cjpe.2017.0018
图1   分室培养系统示意图。以0.45 μm微孔滤膜区隔不同分室。AM和NM分别代表供体植物接种AM真菌和不接种对照处理。 处理分为高磷和低磷(10 mg?kg-1和100 mg?kg-1)两个水平, 每个处理三个重复(n = 3)。
图2   不同磷浓度下接种AM真菌对玉米植株干质量的影响(平均值±标准偏差)。LP和HP分别代表低磷和高磷处理。AMD和NMD分别代表供体植物接种AM真菌和不接种对照处理; AMR和NMR分别代表受体植物受到AM分泌物处理和对照处理。柱形上方标示不同字母代表不同处理间在5%水平有显著性差异。“#”代表在相同接种处理下不同磷水平之间在5%水平差异显著。
图3   不同磷浓度下接种AM真菌对玉米植株磷浓度的影响(平均值±标准偏差)。LP和HP分别代表低磷和高磷处理。AMD和NMD代表供体植物接种AM真菌和不接种对照处理; AMR和NMR代表供体和受体植物受到AM分泌物处理和对照处理。不同字母代表处理间在5%水平上有显著性差异。“#”代表在相同AM真菌分泌物受体不同磷浓度处理间在5%水平上差异显著。“*”代表在相同磷浓度处理下AM真菌处理间在5%水平上差异显著。
图4   不同磷水平下AM真菌碳磷代谢相关基因表达(平均值±标准偏差)。LP为低磷处理, HP为高磷处理; *表示不同磷水平之间差异显著(p < 0.05)。GiPT, AM真菌磷转运蛋白基因; NGT1, N-乙酰葡糖胺(GlcNAc)转运蛋白基因; HXK1b, GlcNAc激酶b基因; AGM1, GlcNAc磷酸变位酶基因; UAP1, UDP-GlcNAc焦磷酸化酶基因; CHS1, 几丁质合酶基因; DAC1, GlcNAc-6-磷酸去乙酰化酶基因; NAG1, 葡糖胺-6-磷酸异构酶基因。
图5   不同磷水平下供体玉米碳磷代谢基因表达情况(平均值±标准偏差)。LP和HP分别代表低磷和高磷处理。AMD和NMD代表供体植物接种AM真菌和不接种对照处理。柱形上方标示不同字母代表相应处理之间在5%水平有显著性差异。“#”表示相同接种处理不同磷水平之间在5%水平差异显著。Pht1;2, Pht1;6, 磷转运蛋白基因; PEPC, 磷酸烯醇式丙酮酸羧化酶基因; G3PT, 甘油-3-磷酸转运蛋白基因; TC289, 无机焦磷酸化酶基因; MAS1, 苹果酸合酶基因。
图6   不同磷水平下受体玉米碳磷代谢相关基因表达情况(平均值±标准偏差)。LP和HP分别代表低磷和高磷处理。AMR和NMR代表供体和受体植物受到AM分泌物处理和对照处理。柱形上方标示不同字母代表相应处理之间在5%水平有显著性差异。“#”表示相同接种处理不同磷水平之间在5%水平差异显著, 而“$”代表在相同磷水平下不同接种处理之间在5%水平上差异显著。Pht1;2, Pht1;6, 磷转运蛋白基因; PEPC, 磷酸烯醇式丙酮酸羧化酶基因; G3PT, 甘油-3-磷酸转运蛋白基因; TC289, 无机焦磷酸化酶基因; MAS1, 苹果酸合酶基因。
附录III   植物干质量、磷含量、碳磷代谢基因表达的双因素方差分析结果
丛枝菌根真菌通过上调根系及自身水孔蛋白基因表达提高玉米抗旱性
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