Effects of Arbuscular Mycorrhizal Fungi on Rice Growth Under Different Flooding and Shading Regimes

Abstract

Arbuscular mycorrhizal fungi (AMF) are present in paddy fields, where they suffer from periodic soil flooding and sometimes shading stress, but their interaction with rice plants in these environments is not yet fully explained. Based on two greenhouse experiments, we examined rice-growth response to AMF under different flooding and/or shading regimes to survey the regulatory effects of flooding on the mycorrhizal responses of rice plants under different light conditions. AMF had positive or neutral effects on the growth and yields of both tested rice varieties under non-flooding conditions but suppressed them under all flooding and/or shading regimes, emphasizing the high importance of flooding and shading conditions in determining the mycorrhizal effects. Further analyses indicated that flooding and shading both reduced the AMF colonization and extraradical hyphal density (EHD), implying a possible reduction of carbon investment from rice to AMF. The expression profiles of mycorrhizal P pathway marker genes (GintPT and OsPT11) suggested the P delivery from AMF to rice roots under all flooding and shading conditions. Nevertheless, flooding and shading both decreased the mycorrhizal P benefit of rice plants, as indicated by the significant decrease of mycorrhizal P responses (MPRs), contributing to the negative mycorrhizal effects on rice production. The expression profiles of rice defense marker genes OsPR1 and OsPBZ1 suggested that regardless of mycorrhizal growth responses (MGRs), AMF colonization triggered the basal defense response, especially under shading conditions, implying the multifaceted functions of AMF symbiosis and their effects on rice performance. In conclusion, this study found that flooding and shading both modulated the outcome of AMF symbiosis for rice plants, partially by influencing the mycorrhizal P benefit. This finding has important implications for AMF application in rice production.

Roles of Arbuscular mycorrhizal Fungi as a Biocontrol Agent in the Control of Plant Diseases

“…Inoculation of tomatoes under F. oxysporum stress can promote the absorption of K, N, P, Ca, Mn, Zn, and other elements), increase chlorophyll and soluble sugar content, and increase the number of branches and leaves of the plant. Enhanced biological activity indirectly improves the plant’s tolerance to pests and diseases [ 74 , 75 , 76 ]. A study found that the growth of olives damaged by M. incognita and M. javanica significantly improved after inoculation with AMF, and the biomass increased by 88.9% [ 77 ].…”

Variation of growth and transcriptome responses to arbuscular mycorrhizal symbiosis in different foxtail millet lines

“…S3 ). Studies of different crop species have shown that the mycorrhizal growth responses are affected by crop species, crop varieties, AMF species, soil fertility and growth conditions (Bernaola and Stout 2019 ; Campo et al 2020 ; Eo and Eom 2009 ; Li et al 2006 , 2018 ; Wang et al 2016 , 2021 ). For example, in Li et al ( 2018 ), the biomass and nutrient content in mycorrhizal wheat were significantly lower than mock-treated plants which might be attributed to high plant density and competition of nutrients between AMF and plants under low nutrient treatments.…”

Arbuscular Mycorrhizal Fungi and Microbes Interaction in Rice Mycorrhizosphere

“…Some studies have reported that AMF are rare or absent in the rice roots of flooded paddy fields [12,13], while an increasing number of studies have demonstrated the presence of AMF colonization inside rice roots in paddy fields [14][15][16][17]. The mycorrhizal growth response of rice plants differs, ranging from positive to negative [4,[18][19][20][21][22][23][24].…”