Root hair phenotypes influence nitrogen acquisition in maize

Abstract

Background and Aims The utility of root hairs for nitrogen (N) acquisition is poorly understood. Methods We explored the utility of root hairs for N acquisition in the functional-structural model SimRoot and with maize genotypes with variable root hair length (RHL) in greenhouse and field environments. Key Results Simulation results indicate that long, dense root hairs can improve N acquisition under varying N availability. In the greenhouse, ammonium availability had no effect on RHL and low nitrate availability increased RHL, while in the field low N reduced RHL. Longer RHL was associated with 216% increase in biomass and 237% increase in plant N content under low N conditions in the greenhouse and a 250% increase in biomass and 200% increase in plant N content in the field compared with short RHL phenotypes. In a low N field environment, genotypes with long RHL had 267% greater yield than those with short RHL. We speculate that long root hairs improve N capture by increased root surface area and expanded soil exploration beyond the N depletion zone surrounding the root surface. Conclusions We conclude that root hairs play an important role in nitrogen acquisition. We suggest that root hairs merit consideration as a breeding target for improved N acquisition in maize and other crops.

N-dependent dynamics of root growth and nitrate and ammonium uptake are altered by the bacterium Herbaspirillum seropedicae in the cereal model Brachypodium distachyon

“…Studies of wild grasses reported shorter root hairs with increased N availability ( Boot and Mensink, 1990 ). Recently a modeling approach indicated that root hairs are important during N deficiency ( Saengwilai et al , 2021 ). We conclude that root hair length is a trait worthy of further investigation for more N-efficient varieties, and that plant development is an important variable for full understanding of the contribution of length.…”

Improving Soil Resource Uptake by Plants Through Capitalizing on Synergies Between Root Architecture and Anatomy and Root-Associated Microorganisms

“…An excellent example of a direct effect of root anatomy on soil resource capture is that of root hairs. Variation in root hair length and density is associated with the volume of the diffusion depletion zone surrounding roots, and therefore with the exploitation of rhizosphere resources, including most notably P ( Bates and Lynch, 2000 ), which is highly immobile in the soil, but also including nitrate, a mobile resource ( Saengwilai et al, 2021 ). Anatomical phenes that reduce the metabolic cost of soil exploration often improve soil resource capture ( Lynch, 2015 , 2019 ; Lynch et al, 2021 ).…”

Comparative phenomics of root architecture and anatomy in Phaseolus species

“…and nitrogen (Saengwilai et al, 2021), while incurring little metabolic cost (Bates & Lynch, 2000b). Xylem vessels are another anatomical feature that are responsible for the bulk of axial transport of water and nutrients through the root system.…”

“…Root hairs are subcellular outgrowths of epidermal cells and are another anatomical phene that expand the volume of soil foraged in the rhizosphere. Root hairs have been shown in modeling and empirical studies to benefit the capture of immobile nutrients like phosphorus (Bates & Lynch, 2000a; Gahoonia & Nielsen, 1998; Miguel et al., 2015) as well as mobile resources like water (Carminati et al., 2017), and nitrogen (Saengwilai et al., 2021), while incurring little metabolic cost (Bates & Lynch, 2000b). Xylem vessels are another anatomical feature that are responsible for the bulk of axial transport of water and nutrients through the root system.…”