Mechanisms of Arbuscular Mycorrhizal Fungal Symbiosis in Promoting Growth of Astragalus Seedlings

doi:10.13560/j.cnki.biotech.bull.1985.2025-1317

Abstract

Abstract:

Objective To explore the growth-promoting effect and mechanism of Glomus mosseae inoculation on A. mongholicus. Method The experiment included two groups: a control group (CK) without Glomus mosseae and an AMF group inoculated with G. mosseae. After cultivation, samples were collected during the rapid growth period of A. mongholicus. The root colonization rate of G. mosseae, as well as growth parameters including plant height, root length, taproot diameter, and fresh and dry weights, were measured. RNA-Seq technology was used to analyze differentially expressed genes (DEGs) between treatments to further explore the effects on gene expression and molecular mechanisms in A. mongholicus. Result Inoculation with Glomus mosseae promoted the growth and development of A. mongholicus. Specifically, the number of lateral roots increased by 100%, plant height by 42.01%, taproot diameter by 50%, fresh weight of aboveground parts by 37.84%, fresh weight of belowground parts by 97.67%, dry weight of aboveground parts by 75.36%, and dry weight of belowground parts by 100%. No significant difference was observed in root length due to limited pot space. The root colonization rate of G. mosseae on A. mongholicus reached 91.26%, indicating the formation of a stable symbiotic relationship. A total of 584 DEGs were identified from the transcriptome data. Functional enrichment analysis showed that these DEGs were mainly enriched in the biosynthesis pathways of phenylpropanoids and isoflavonoids, as well as the plant hormone signal transduction pathway. Transcription factors such as bHLH and ERF played central regulatory roles in these pathways. Conclusion Glomus mosseae can regulate key secondary metabolic processes through plant hormone signals, optimize root development, and thereby promote the growth of A. mongholicus.

Key words: Arbuscular mycorrhizal fungi, Astragalus membranaceus, interaction, growth indicators, promoting effect, transcriptome

LIU Hong-jun, ZHANG sheng, YANG Wei-ping, LU Geng-long, BAI Yu-guo, LI Wan-di, NIU Jing-ping, LIANG Jian-ping, SHI Zhi-yong. Mechanisms of Arbuscular Mycorrhizal Fungal Symbiosis in Promoting Growth of Astragalus Seedlings[J]. Biotechnology Bulletin, 2026, 42(10): 257-268.

Figures/Tables 9

Fig. 1 The influence of AMF inoculation treatment on growth and development of Astragalus membranaceusA, G: Phenotypic characteristics of mycorrhizal and non-mycorrhizal plants after 90 days of growth. B-E: Root length, plant height, taproot diameter, and fresh and dry weights of belowground and aboveground parts of mycorrhizal and non-mycorrhizal plants after 90 days of growth. F: Root staining of inoculated and non-inoculated plants after 90 days. *P<0.05. ****P<0.000 1

Fig. 2 PCA analysis and volcano plot of differentially expressed genes of transcriptome dataA: PCA analysis among samples. B: Differentially expressed genes identified by comparative analysis between AMF and CK groups, with screening thresholds set as |log₂FC|≥1 & Padjust<0.05. A total of 320 up-regulated genes are marked in red, and 267 down-regulated genes are marked in blue

Fig. 3 Functional annotation of differentially expressed genesA: GO functional annotation; B: KEGG functional annotation

Fig. 4 KEGG pathway enrichment of DEGsThe x-axis indicates to the number of pathway-specific DEGs divided by the total number of DEGs, the y-axis represents the KEGG pathways

Fig. 5 Phenylpropanoid biosynthesis pathwayPAL: Phenylalanine ammonia-lyase; CYP73A: Cinnamate-4-hydroxylase; 4CL: 4-coumarate: CoA ligase; SHT: Serotonin N-hydroxycinnamoyltransferase; CCR: Cinnamoyl-CoA reductase; CAD6: Cinnamyl alcohol dehydrogenase 6; PER/RIP1/PNC1: Peroxidases; ALDH2: Aldehyde dehydrogenase 2. Genes marked in purple are differentially expressed genes, accompanied by a gene expression heatmap

Fig. 6 Isoflavonoid biosynthesis pathwayCYP93C: Cytochrome P450 enzyme family; CYP81E1/E7: Cytochrome P450 enzyme; IFR: Cytochrome P450 monooxygenase; PTS: Pterocarpan synthase. Genes marked in purple are differentially expressed genes, accompanied by a gene expression heatmap

Fig. 7 Plant hormone signal transduction pathwayAuxin: Auxin; AUX/IAA, GH3, SAUR: Early auxin-responsive genes. Cytokinin: Cytokinin; A-ARR: Cytokinin response factor. Abscisic acid: Abscisic acid; SnRK2: Sucrose non-fermenting-1-related protein kinase 2. Brassinosteroid: Brassinosteroid; BKI1: Negative regulator of brassinolide receptor kinase BRI1. Jasmonic acid: Jasmonic acid; COI1: Jasmonate receptor; JAZ: Transcriptional repressor. Salicylic acid: Salicylic acid; PR-1: Pathogenesis-related protein 1. Genes marked in purple are differentially expressed genes, accompanied by a gene expression heatmap

Fig. 8 Transcription factor regulatory networkA: The number of DEGs regulated by different transcription factor families, and the size of each respective family. B: Regulatory network diagram of differentially expressed genes and transcription factors in the three pathways

Fig. 9 Validation of differentially expressed genes using RT-qPCRCK: Samples not inoculated with G. mosseae; AMF: Samples inoculated with G. mosseae

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