Quantification of Arbuscular Mycorrhizal Fungi Colonization Rate in the Study of Invasive Alien Plants

Summary

This protocol provides a simple and easy-to-use approach for determining the colonization rate of Arbuscular mycorrhizal fungi (AMF) in the roots of invasive plants.

Abstract

Arbuscular mycorrhizal fungi (AMF) are widely distributed soil fungi in ecosystems and can form symbiotic associations (mycorrhizae) with the roots of most terrestrial plants. Plants provide carbon sources to AMF through mycorrhizal associations, while AMF hyphae can expand the range of nutrient absorption by roots and promote plant nutrient uptake. There are many different species of AMF, and the symbiotic relationships between different species of AMF and different plants vary. Invasive plants can enrich AMF species with better symbiotic capabilities through root exudates, promoting their growth and thereby increasing their colonization in invasive plant roots. At the same time, invasive plants can also disrupt the symbiotic relationship between AMF and native plants, affecting the local plant community, which is one of the mechanisms for successful plant invasion. The colonization rate of AMF in the roots of invasive and native plants indirectly reflects the role of AMF in the process of invasive plant invasion. In this method, collected plant roots can be processed directly or saved in a fixative for later batch processing. Through decolorization, acidification, staining, and destaining treatment of roots, the hyphae, spores, and arbuscular structures of AMF in the root system can be clearly observed. This method can be completed in a basic laboratory to observe and calculate the colonization rate of AMF in the root systems of invasive plants.

Introduction

Mycorrhizal fungi are prevalent in natural ecosystems and establish symbiotic relationships with the roots of most plants, forming mycorrhizae¹. These associations are mutually beneficial, as plants provide photosynthetically fixed carbon compounds such as fatty acids and sugars to support the growth of mycorrhizal fungi, while the fungi reciprocate by supplying mineral nutrients like phosphorus and nitrogen to the host plants, thereby promoting plant growth². Based on their mycorrhizal types formed with plant roots, mycorrhizal fungi can be divided into four main types: ectomycorrhizal (ECM) fungi, ericoid mycorrhizal (....

Protocol

We conducted experiments using one invasive plant F. bidentis and one native plant Setaria viridis. Both plants were grown in experimental plots at the Langfang Scientific Research Pilot Base of the Chinese Academy of Agricultural Sciences (CAAS), Hebei, China. Each plant species was individually planted in separate plots, with each plot measuring 2 m x 3 m and a 1-meter gap between plots. The plants were left to grow naturally, and after approximately two months, root samples were collected.

1. Root preparation and preservation

1. For each plot, randomly select three plants with similar growth co....

Results

The staining results of the invasive plant roots using this method are shown in Figure 1. The structures (hyphae, arbuscules, spores, and vesicles) of AMF are stained red, the root cortex cells are stained light red after destaining, and the central cylinder is stained red. This staining result is sufficient to distinguish the fungal structures as AMF mainly exists in the plant's cortex. From the staining result, clear structures such as arbuscules (A), intraradical hyphae (IH), extraradical.......

Discussion

The interactions between invasive plants and AMF are complex and diverse. Studying these interactions is crucial for understanding the success of invasive plants and their ecological effects. They can influence the invasive ability of plants, the structure and function of soil ecosystems, and the competitiveness of native plants. The colonization rate serves as an important indicator for studying the relationship between invasive plants and AMF. It provides a quantitative measure for establishing symbiotic relationships,.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
70% Alcohol	Shanghai Aladdin Biochemical Technology Co., Ltd	R433197
Acetic acid solution	Shanghai Aladdin Biochemical Technology Co., Ltd	A116166
Acid fuchsin	Shanghai Aladdin Biochemical Technology Co., Ltd	A104917
Formaldehyde solution, Formalin	Shanghai Aladdin Biochemical Technology Co., Ltd	F111941
Glycerol	Shanghai Aladdin Biochemical Technology Co., Ltd	G116203
Hydrochloric acid, HCl	Shanghai Aladdin Biochemical Technology Co., Ltd	H399657
Lactic acid	Shanghai Aladdin Biochemical Technology Co., Ltd	L432769
Manual System Microscope BX43	Olympus (China) co., Ltd
Potassium hydroxide, KOH	Shanghai Aladdin Biochemical Technology Co., Ltd	P112284