Effects of arbuscular mycorrhizal fungus inoculation on the growth and nitrogen metabolism of Catalpa bungei C.A.Mey. under different nitrogen levels

Abstract

Evidence suggests that arbuscular mycorrhizal fungi (AMF) may promote the growth of woody plants. However, the effects of AMF on nitrogen (N) metabolism in plants, especially trees, and its regulatory mechanism are rarely reported. Here, the effects of AMF inoculation on the growth and N nutrition status of Catalpa bungei under different N levels were reported. Three N levels (low, medium, high) and two mycorrhizal inoculation treatments (inoculation with Rhizophagus intraradices or not) were used with factorial design. The results showed that medium N could significantly improve the physiological metabolism and growth of C. bungei seedlings. However, when N was excessive, growth was significantly inhibited whether inoculated AMF or not. Compared with non-inoculated treatments, AMF inoculation could promote the absorption of N and P, improve photosynthesis under low to medium N levels, thus promoting the growth of seedlings. AMF changed the biomass allocation in seedlings by reducing the stem mass ratio and root/shoot ratio, and increasing the leaf mass ratio. At medium N levels, compared with non-inoculated treatment, AMF inoculation could significantly promote root growth by changing root hormone levels and improving root architecture and root activity. Under N addition, AMF inoculation could improve the absorption and assimilation of N by regulating the expression of key enzyme genes of N metabolism and nitrate transporter genes (NRT2.4, NRT2.5, NRT2.7) in roots, and enhancing the activities of the key enzyme of N metabolism. This study may provide a reference for the application of AMF in the cultivation and afforestation technology of C. bungei in Northwest China.

Exogenous Easily Extractable Glomalin-Related Soil Protein Induces Differential Response in Plant Growth of Tea Plants via Regulating Water Channel Protein Expression

“…Meanwhile, highstrength (3/4 and full-strength) exogenous EE-GRSP treatments dramatically reduced the contents of glucose, total amino acids, and flavonoids in the tea leaves, which may be related to the eutrophication in the rhizosphere of tea plants caused by exogenous GRSP application. Generally, excessive organic or inorganic content in the soil may reduce the decomposition and release of proteases by the roots, thereby inhibiting the absorption and utilization of nutrients, such as nitrogen, by plant roots [29,30]. Therefore, we speculate that, in the present study, high-strength exogenous EE-GRSP application resulted in eutrophication of the tea rhizosphere soil, thereby decreasing nutrient absorption and utilization, as well as the transport efficiency of the tea roots.…”

Arbuscular Mycorrhizal Fungi and Higher Plants

“…Evaluating the effect of the combined application of AMF and PGPR revealed that the mixture of both microbial substrates enhanced rice plants' nutritional content and yield. In addition to that, the consortium of AMF and PGPR significantly enhanced the levels of inorganic nutrients like boron (B), N, P, and K in rice field soils, thus providing the plants with sufficient nutrients for proper growth and yield (Chen et al 2023a). Similarly, inoculation of AMF and PGPR consortium on date palms undergoing Fusarium wilt decreased the disease incidences.…”

Exogenous Easily Extractable Glomalin-Related Soil Protein Stimulates Plant Growth by Regulating Tonoplast Intrinsic Protein Expression in Lemon

“…Additionally, exogenous EE-GRSP applications did not significantly affect the root N content, but high-strength EE-GRSP applications dramatically decreased the leaf N content, and it is possible that GRSP only maintained the plants’ N at its required stable level. After all, excessive N concentrations would inhibit plant growth [ 38 ].…”