Arbuscular mycorrhizal colonization outcompetes root hairs in maize under low phosphorus availability

Abstract

Background and Aims An increase in the root hair length and density, as well as the development of arbuscular mycorrhiza symbiosis, are two alternative strategies of most plants to increase the root-soil surface area under phosphorus (P) deficiency. Across many plant species, root hair length and mycorrhization density are inversely correlated. Root architectures, rooting density and physiology also differ between species. This study aims to understand the relationship among root hairs, arbuscular mycorrhizal fungi (AMF) colonisation, plant growth, P acquisition, and mycorrhizal-specific Pi transporter gene expression of maize Methods Using nearly isogenic maize lines, the B73 wild type and the rth3 root hairless mutant, we quantified the effect of root hairs and AMF infection in a calcareous soil under P-deficiency through a combined analysis of morphological, physiological and molecular factors Key Results Wild type root hairs extended the rhizosphere for acid phosphatase activity by 0.5 mm compared to the rth3 hairless mutant, as measured by in situ zymography. Total root length of the wild type was longer than rth3 under P-deficiency. Higher AMF colonisation and mycorrhiza-induced phosphate transporter gene expression were identified in the mutant under P-deficiency, but plant growth and P acquisition were similar between mutant and the wild type. Ultimately, the mycorrhizal dependency of maize was 33% higher than the root hair dependency Conclusions The results identified a larger mycorrhizal dependency than root hair dependency under P-deficiency in maize. Root hairs and AMF inoculation are two alternative ways to increase Pi acquisition under P-deficiency, but these two strategies compete with each other

Root Hairs Matter at Field Scale for Maize Shoot Growth and Nutrient Uptake, But Root Trait Plasticity is Primarily Triggered by Texture and Drought

“…We expected that the rth3 plants would show higher colonisation levels, especially as mycorrhiza formation can actually compensate for the loss of root hairs in the rth3 mutant. By implementing an AMF inoculation experiment, Ma et al (2021) showed that the positive effects of mycorrhiza formation on plant growth and P acquisition in rth3 were 1.5-to 3.9-fold greater than in the wild-type, and AMF colonisation complemented growth and P acquisition defects of the mutant. Interestingly, mycorrhizas also effectively substituted root hairs in P uptake in barley (Jakobsen et al 2005).…”

Flint maize root mycorrhization and organic acid exudates under phosphorus deficiency: Trends in breeding lines and doubled haploid lines from landraces

“…The majority of plant species, including crop species, are responsive to mycorrhizal symbiosis. In maize, arbuscular mycorrhiza formation has been demonstrated to be more important than root hairs for seedling growth under low P availability ( Ma et al, 2021). The degree to which plants respond to mycorrhizal symbiosis depends on: (1) the plant species and its root traits; (2) soil conditions, such as inherent fertility, pH, and management; and (3) AMF species.…”

Interactive effects of silicon and arbuscular mycorrhiza on root growth, uptake of several soil elements, antioxidant potential, and secondary metabolites of Licorice (Glycyrrhiza glabra L.) under water-deficit condition

“…AMF helps host-plants partly maintain their rate of development, despite the effects of stress, by regulating a series of signaling pathways between the plant and the fungus, thereby facilitating the photosynthetic rate and other gas exchange-related features (Huang et al, 2020). Inside plant roots and in the soil, AMF can substantially increase the surface area available for nutrient absorption by plants (Gavito et al, 2019;Ma et al, 2021). Therefore, in the case of mycorrhiza and Si, root traits in many cases are frequently bound to improve.…”