Biology subjects

Whalen, J. K.

Publications and source records attributed to Whalen, J. K..

2 recordsLinked to original sources

bioRxiv2025

Exogenous auxins for proline regulation in heat-stressed plants

Microbial indole-3-acetic acid (IAA) has long been recognized as a driver of plant growth and developmental plasticity. Recent studies show that microbial IAA production is sustained or even enhanced at elevated temperatures, suggesting that microbial auxins may contribute to plant thermotolerance by stabilizing auxin signalling and supporting metabolic adaptation. Here, we synthesize emerging molecular and physiological evidence linking microbial IAA to proline turnover during thermomorphogenesis. We propose that microbial IAA establishes a regulatory window in which proline metabolism transitions between early osmoprotective synthesis and later catabolism that fuels elongation and redox balance. This integration involves crosstalk between the HSP90-TIR1 auxin perception module, heat-responsive MPK-IAA8 signalling, mitochondrial redox regulators (SSR1, HSCA2), and hormonal interactions with abscisic acid and ethylene. We outlined four mechanistic hypotheses and associated experiments to test how microbial IAA modulates proline homeostasis. This framework highlights microbial auxins as metabolic integrators during heat stress and provides a conceptual basis for leveraging auxin-producing microbes to enhance plant resilience under global warming. HighlightMicrobial auxins modulate the proline cycle during heat stress by integrating hormonal, redox, and mitochondrial signals, offering a mechanistic framework for how microbial IAA enhances thermomorphogenesis and plant heat resilience.

plant biology↗

bioRxiv2024

Water-conducting roots responsible for nitrogen uptake in maize (Zea mays)

Nitrate (NO3-) uptake is primarily driven by mass flow and varies among maize root types. The importance of embryonic and crown roots in acquiring NO3- was determined here in wet and dry soils. Maize was grown in a split-root pot that segregated the embryonic and crown roots. The soil was moistened to water potentials of either -5kPa or -30kPa. A partial N mass balance was made by destructively sampling shoots, roots, and soils after 0, 24, and 48 h following 15N-KNO3 injection at the V3 and V6 stages. Gross nitrification was assessed using a 15N isotope dilution technique. At the V3 stage, crown roots had 202% more N uptake than embryonic roots in wet soil (-5 kPa). However, in dry soil (-30 kPa), N uptake was similar for embryonic and crown roots, possibly due to an 80% reduction of hydraulic conductance in crown roots. By the V6 stage, crown roots dominated N uptake, with embryonic roots supplying < 20% of N uptake. Soil gross nitrification rate was similar for root types. The present studies indicated that maize NO3- uptake depends primarily on the crown roots, due to their capacity to extract water and NO3- from soil, even under dry conditions. HighlightThis study reveals how different maize root types contribute to nitrate uptake under varying soil moisture conditions, suggesting that soil water management is important to ensure optimal nitrogen uptake.

plant biology↗