Variation in Populus euphratica foliar carbon isotope composition and osmotic solute for different groundwater depths in an arid region of China

Abstract

Water use efficiency (WUE) is an important trait associated with plant acclimation caused by water deficits, and δ13C is a good surrogate of WUE under conditions of water deficits. Water deficiency also enhances the accumulation of compatible solutes in the leaves. In this study, variations in foliar δ(13)C values and main osmotic solutes were investigated. Those included total soluble sugar (TSS), sucrose, free proline, glycine betaine (GB), and inorganic ionic (K+, Ca2+, and Cl-) content of Populus euphratica for different groundwater depths in a Ejina desert riparian forest, China. Results indicated that foliar δ13C values in the P. euphratica for different groundwater depths ranged from -29.14±0.06 to -25.84±0.04 ‰. Foliar δ13C signatures became richer as groundwater levels declined. TSS, sucrose, free proline, GB, and K+ were accumulated in P. euphratica foliage with developing plant growth and increasing groundwater depth. Ca2+ and Cl- content increased under stronger P. euphratica transpiration rates for shallower groundwater depths (1-2.5 m) and decreased for deeper groundwater depths (greater than 3.0 m). Moreover, correlations between δ13C, osmotic solutes, and groundwater depths showed that the primary osmotic solutes were TSS, sucrose, proline, GB, and K+. Correlations also showed that δ13C was not only a useful measure for P. euphratica-integrated WUE but also could be used as an indicator reflecting some physiological osmotic indexes.

Relationships between foliar carbon isotope composition and elements of C3 species in grasslands of Inner Mongolia, China

“…Plant Ecol (2016) 217:883-897 893 Relationship between foliar d 13 C and K Potassium is an osmoticum that plays an important role in osmotic adjustment by its active accumulation in cells to reduce osmotic potential, thence attracting water into cells (Si et al 2015). Thus, plants subjected to drought stress could actively accumulate large quantities of K for the purpose of osmotic adjustment and in concomitance show higher WUE, and correspondingly d…”

“…Phosphorus (P) can affect photosynthesis indirectly through its effects on Calvin cycle enzymes and enzymes related to the synthesis of protein, RNA, and DNA (Walker et al 2014(Walker et al , 1986Warren and Adams 2002). Potassium (K) plays an important role related to stomatal behavior, enzyme activity, photosynthesis, and osmotic adjustment (Amrutha et al 2007;Si et al 2015). Further, foliar element ratios, e.g., C/N (foliar carbon:nitrogen ratio), C/P (foliar carbon:phosphorus ratio), and N/P (foliar nitrogen:phosphorus ratio), are also key traits of ecological relevance and link with d 13 C through their correlation with water use efficiency (WUE).…”

“…This result also indicates the possibility that species in Inner Mongolia surviving in dry conditions may profit from their higher WUE through partial stomatal closure rather than osmotic adjustment through more K absorption. Alternatively, K may not be the primary osmoticum in species of Inner Mongolia, but instead organic osmotica such as sugars and amino acids may constitute the solute (Guy et al 1989;Si et al 2015).…”

Soluble sugar drives plant leaf turgor, restricts plant growth, and regulates plant hydraulic capacity of Haloxylon ammodendron to different groundwater level

“…Osmotic adjustment protects against declining water availability by counteracting turgor loss (Burgess, 2006;Cushman, 2001;Si, Feng, Yu, Zhao, & Li, 2015). Pressure-volume (P-V) analyses have revealed that osmoregulation increases drought resistance as DGW increases (Zolfaghar, Villalobos-Vega, Cleverly, et al, 2015).…”

“…By increasing and maintaining higher levels of intracellular compatible solutes, osmotic adjustment enhances the capacity for turgor maintenance (Cater, 2011;Gebre, Tschaplinski, Tuskan, & Todd, 1998;Nolan et al, 2017) via active accumulation of in/organic solutes in cells in response to deceases in the cellular environment's Ψ . Declining cell osmotic potential (π) further attracts water into cells maintaining turgor pressure (Cater, 2011;Si et al, 2015). However, attributes that confer the capacity to tolerate water stress (lower saturated turgor) may limit growth potential under favorable water conditions (Chen et al, 2015;Fernandez & Reynolds, 2000;Leuschner, Wedde, & Luebbe, 2019).…”