Strategies for Optimization of Mineral Nutrient Transport in Plants: Multilevel Regulation of Nutrient-Dependent Dynamics of Root Architecture and Transporter Activity

Abstract

How do sessile plants cope with irregularities in soil nutrient availability? The uptake of essential minerals from the soil influences plant growth and development. However, most environments do not provide sufficient nutrients; rather nutrient distribution in the soil can be uneven and change temporally according to environmental factors. To maintain mineral nutrient homeostasis in their tissues, plants have evolved sophisticated systems for coping with spatial and temporal variability in soil nutrient concentrations. Among these are mechanisms for modulating root system architecture in response to nutrient availability. This review discusses recent advances in knowledge of the two important strategies for optimizing nutrient uptake and translocation in plants: root architecture modification and transporter expression control in response to nutrient availability. Recent studies have determined (i) nutrient-specific root patterns; (ii) their physiological consequences; and (iii) the molecular mechanisms underlying these modulation systems that operate to facilitate efficient nutrient acquisition. Another mechanism employed by plants in nutrient-heterogeneous soils involves modification of nutrient transport activities in a nutrient concentration-dependent manner. In recent years, considerable progress has been made in characterizing the diverse functions of transporters for specific nutrients; it is now clear that the expression and activities of nutrient transporters are finely regulated in multiple steps at both the transcriptional and post-transcriptional levels for adaptation to a wide range of nutrient conditions.

Small molecules below‐ground: the role of specialized metabolites in the rhizosphere

“…Bioavailability of minerals and trace elements is essential for plant development as they serve as cofactors for a wide range of cellular process (White et al, 2014). The main source of minerals for plants is restricted to active acquisition through the root tissue (Aibara and Miwa, 2014). Hence, availability of minerals is strongly dictated by soil chemistry.…”

Divergent scaling of respiration rates to nitrogen and phosphorus across four woody seedlings between different growing seasons

“…This observation is not surprising because the uptake, transport, and allocation mechanisms for P and N are very similar in plants (Feild & Brodribb, 2001; Jeschke, Kirkby, Peuke, Pate, & Hartung, 1997; Kilgore, Patel, Sharma, Maya, & Kielhorn, 2014; Lynch, 1995; Mimura, 1995; Niklas et al., 2005; Schachtman, Reid, & Ayling, 1998). However, our results also show that seedling P content scales isometrically with N content across the four species, whereas prior studies report that a ⅔ scaling exponent for P versus N across large plants (Han, Fang, Guo, & Zhang, 2005; Niklas, 2006; Niklas et al., 2005; Reich et al., 2010; Wright et al., 2004).…”

Modeling of root nitrate responses suggests preferential foraging arises from the integration of demand, supply and local presence signals

“…Additionally, an interesting direction would be to attempt to extend the explanatory power of the model to the apparent sensitivity of root growth to temporal changes in nitrate levels (Shemesh et al, 2010a(Shemesh et al, , 2010b(Shemesh et al, , 2011. This likely requires the incorporation of additional model components, such as internal nitrate stores, or the regulation of expression of nitrate transporters (Aibara and Miwa, 2014)). Other interesting directions for expansion are to attempt to incorporate the effects of neighboring plants competing for nitrate (Ljubotina and Cahill Jr, 2019), requiring at least the incorporation of soil nitrate dynamics (Robinson, 2001), and potentially plant-plant communication mechanisms.…”