Effect of an Ectomycorrhizal Fungus on the Growth of Castanea henryi Seedlings and the Seasonal Variation of Root Tips’ Structure and Physiology

Abstract

Castanea henryi is a ubiquitous hardwood chestnut species in southern China and is important both ecologically and economically. It is mainly cultivated for nut production, just like other chestnut species. However, the establishment of C. henryi seedlings in a new orchard has proven to be difficult because few seedlings survive transplanting due to the incompatibility of their coarse root architecture with nutrient-depleted red acid soils in southern China. Root architecture can be profoundly modified and nutrient can be stress alleviated due to the association of roots with ectomycorrhizal (ECM) fungi. Boletus edulis is an ECM fungus with edible and medicinal fruiting bodies. However, its impact on plant growth varies with the plant species it is associated with. In order to elucidate the role of B. edulis in C. henryi afforestation, we evaluated growth parameters and soil enzymatic activities, as well as seasonal variations in physiology and structure of ECM root tips. Growth responses and soil enzymatic activities were measured 6 months after inoculation. The physiological characteristics of root tips were also compared at various seasons throughout the year. B. edulis colonization of C. henryi roots was successful at a 60% colonization rate. Height, base diameter, and biomass (especially the underground part) of inoculated seedlings (JG) were higher than those of uninoculated seedlings (CK). JG had higher root total length, root surface area, root volume, root average diameter, and number of root tips than CK. Additionally, JG exhibited higher total nitrogen and phosphorus content. Abnormal mantle and Harting net were observed in winter. No matter the season, ECM tips had higher antioxidant enzyme activities, root activities, soluble protein content, and lower malondialdehyde compared to non-ECM tips (nE) and those without ECM tips (woE), and there were no differences between nE and woE. It is important to understand the growth of the host plant in response to ECM and that the seasonal variation of ECM root tips is important when growing high-quality C. henryi seedlings, due to the crucial role of B. edulis in improving seedling initial survival rate.

Mycorrhizal synthesis and physiological responses of Entoloma clypeatum and Malus robusta

“…Plant hormones regulate root development, in which IAA plays a leading role (Parizot and Beeckman 2012). The accumulation and gradient distribution of endogenous hormones such as IAA in root tips induce the development of mycorrhiza in host plants, thus changing the root architecture of host plants (Xiong 2019). In this study, the mycorrhizal formed by fungi and seedlings is clavate or cylindrical, which is similar to the appearance of mycorrhizal formed by symbiosis with wild Rosaceae plants (Kobayashi and Hatano 2001).…”

Effects of nitrogen addition and root fungal inoculation on the seedling growth and rhizosphere soil microbial community of Pinus tabulaeformis

“…The development of a deep and extensive root system can regulate the absorption of water and nutrients in soil, which ultimately influences biomass production ( Hund et al, 2009 ). This is one of the reasons why ectomycorrhizal fungal or dark septate endophytic inoculation of host plants enhanced the development of the root system under unstressed conditions ( Domínguez-Núñez et al, 2006 ; Wu, 2011 ; Álvarez-Lafuente et al, 2018 ; Li et al, 2019 ; Xiong et al, 2021 ). In addition, ectomycorrhizal fungi and dark septate endophytes may alter auxin metabolism within the host root, which can regulate root development and change root architecture ( Felten et al, 2009 ; Waqas et al, 2012 ; Vayssières et al, 2015 ; Splivallo et al, 2016 ; Priyadharsini and Muthukumar, 2017 ).…”

Differential and Interactive Effects of Scleroderma sp. and Inorganic Phosphate on Nutrient Uptake and Seedling Quality of Castanea henryi

“…Previous studies showed that Scleroderma is a common ECM fungus associated with C. henryi [22], C. mollissima [23], and C. dentata [24]. The role of ECMF in improving plant growth has been evaluated extensively in Castanea species [25,26]. ECMF symbiosis with the host plant resulted in a positive effect on nutrient uptake through the mycelium by the host plant [27].…”