Hypoxia-Responsive Root Hydraulic Conductivity Influences Soybean Cultivar-Specific Waterlogging Tolerance

Abstract

Excess soil moisture induces hypoxic conditions and causes waterlogging injury in soybean [Glycine max (L.) Merr.]. This study investigated the mechanism underlying the development of waterlogging injury. Nine Japanese soybean cultivars with varying degrees of waterlogging tolerance were grown in a hydroponic system for 14 days under hypoxic conditions. Shoot and root biomasses and root hydraulic conductivity were measured at an early vegetative stage for plants under control and hypoxic conditions. Root morphological traits and intramembrane aquaporin proteins were also analyzed. The tolerance of each cultivar to field waterlogging was based on biomass changes induced by the hypoxia treatment. Root hydraulic conductivity responses to hypoxia were associated with changes in total dry weight, leaf dry weight, and leaf area. The effects of hypoxic conditions on root hydraulic conductivity were also represented by the changes in root morphology, such as total root length, thick-root length, and number of root tips. Additionally, a 32.3 kDa aquaporin-like protein seemed to regulate root hydraulic conductivity. Our results from a hydroponic culture suggest that the soybean cultivar-specific responses to hypoxic conditions in the rhizosphere reflect fluctuations in hydraulic conductivity related to root morphological or qualitative changes.

Melatonin and KNO3 Application Improves Growth, Physiological and Biochemical Characteristics of Maize Seedlings under Waterlogging Stress Conditions

“…Waterlogging predominantly affects plants by triggering rhizosphere degeneration, which leads to a decline in root activity and a reduction in water and nutrient absorption, particularly ion absorption [ 8 ]. Plants under waterlogging stress may have reduced uptake of nitrogen, an essential element for the synthesis of amino acids, proteins, enzymes, and nucleic acids [ 9 ]. Following waterlogging, plants often exhibit N deficiency, so that leaves lower on shoots show signs of wilting and yellowing, ultimately inhibiting plant growth and development [ 10 ].…”

The State of the Art in Modeling Waterlogging Impacts on Plants: What Do We Know and What Do We Need to Know

“…Waterlogging‐induced reduction of stomatal conductance is often associated with diminished root hydraulic conductance (Bramley et al, 2010; Jitsuyama, 2017). The phenomenon is more pronounced in the waterlogging‐sensitive plants, possibly due to a higher degree of damage of their root system (e.g., lower biomass).…”

“…Water absorption by roots is at least partially ( ~ 50%) governed by root water channels (aquaporins) of the plasma membrane intrinsic protein (PIP) family (McElrone et al, 2007; Tournaire‐Roux et al, 2003). The production of PIPs aquaporin‐like proteins differs between anaerobic and aerobic conditions among several soybean cultivars with varying degrees of waterlogging tolerance (Jitsuyama, 2017; Tan & Zwiazek, 2019). Incorporating this trait into crop models may help to account for genetic diversity for waterlogging tolerance under waterlogging conditions.…”

The Variation induction of Glycine max through low dose gamma irradiation produces genetic and physiological alteration as source of tolerant variants in waterlogging conditions

“…As compensation for the decrease in the number of roots in waterlogging conditions, plants will tend to form adventitious roots. Adventitious roots are an indicator that plants experience waterlogging stress conditions and show that the plants are adaptable or tolerant to waterlogging (Jitsuyama et al 2017). According to Sembiring et al (2016), the adventitious roots serve to maintain the continuity of oxygen as well as mineral supply and replace the function of the main root, which cannot absorb maximum oxygen in waterlogging stress conditions.…”