Aquaporin regulation in roots controls plant hydraulic conductance, stomatal conductance, and leaf water potential in Pinus radiata under water stress

Abstract

Stomatal regulation is crucial for forest species performance and survival on drought‐prone sites. We investigated the regulation of root and shoot hydraulics in three Pinus radiata clones exposed to drought stress and its coordination with stomatal conductance (gs) and leaf water potential (Ψleaf). All clones experienced a substantial decrease in root‐specific root hydraulic conductance (Kroot‐r) in response to the water stress, but leaf‐specific shoot hydraulic conductance (Kshoot‐l) did not change in any of the clones. The reduction in Kroot‐r caused a decrease in leaf‐specific whole‐plant hydraulic conductance (Kplant‐l). Among clones, the larger the decrease in Kplant‐l, the more stomata closed in response to drought. Rewatering resulted in a quick recovery of Kroot‐r and gs. Our results demonstrated that the reduction in Kplant‐l, attributed to a down regulation of aquaporin activity in roots, was linked to the isohydric stomatal behaviour, resulting in a nearly constant Ψleaf as water stress started. We concluded that higher Kplant‐l is associated with water stress resistance by sustaining a less negative Ψleaf and delaying stomatal closure.

Root water gates and not changes in root structure provide new insights into plant physiological responses and adaptations to drought, flooding and salinity

“…Control plants were irrigated with 2 liters of water twice per week, which was enough to saturate the substrate. For the drought treatment, plants were never irrigated from the start until the end of the experiment (Rodriguez-Gamir et al, 2019). Flooding and flooding plus salinity was imposed by submerging the seedlings to the root-collar (3 cm above the surface) without draining the pots (Pezeshki, 1992).…”

“…mercuric chloride or hydroxyl radicals) demonstrated that AQP down-regulation is the principal cause of alterations of the radial pathway, resulting in a decrease in K root (Ehlert et al, 2009; Knifer and Fricke, 2011; Maurel and Nacry 2020). Despite a recent flurry of studies, compared to reference plants used in molecular studies such as corn, tobacco and Arabidopsis (Siefritz et al, 2002; Lopez et al, 2003; Bramley et al, 2009; Sade et al, 2010; Tan and Zwiazek, 2019), the importance of species differences in AQP regulation in woody plants and its effect within the SPAC is still poorly understood (McElrone et al, 2007; Gambetta et al, 2013; Johnson et al, 2014; Rodriguez-Gamir et al, 2019).…”

Technology of Balanced Identification for Selection of Pine Transpiration Mathematical Model

“…Усложним модель, используя качественную информацию о моделируемом объекте: знание об устьичной природе регуляции потока водяного пара [18,19]. В простейшем случае, когда температура хвои близка к температуре воздуха, поток водяного пара (E) из растения в атмосферу определяется по формуле [20]:…”

“…Функции, определяющие динамику воды: устьичная проводимость (Ust) как функция радиации (Q) и дефицита упругости водяного пара (VPD), функция регулирования устьичной проводимости стволе (Reg) в зависимости от дефицита воды в стволе (WD), функция скорости поступление воды из почвы (FWF) в зависимости от дефицита воды в стволе (WD). Построенная в итоге модель соответствует современным представлениям о регуляции влаги в растении [10][11][12][13][14][15][16][17][18][19][20]22], она показала хорошее качественное совпадение с независимыми экспериментальными данными.…”

Hydraulics of woody plants

“…Another central question in woody plant hydraulics is the role of the roots in determining whole‐plant water transport capacity. Hydraulic failure below ground can determine a species' vulnerability to drought (Johnson et al, ), and one of the studies in this issue reports a role for root aquaporins in regulating whole‐plant water transport, stomatal conductance, and leaf water status (Rodríguez‐Gamir et al, ).…”