Solute contributions to osmotic adjustment in leaf segments of wheat (Triticum aestivum L.) exposed to polyethylene glycol-induced water deficit

ABSTRACT

This study examined osmotic adjustment (OA) and solutes accumulated in leaf segments of wheat cultivar Hartog exposed to polyethylene glycol (PEG)-induced water deficit (WD) in laboratory experiments. Additional 10 mM K⁺ or Na⁺ added to basal solution with PEG −0.5 MPa enhanced leaf OA by up to 100%. Omission of nitrogen from the basal solution suppressed the expression of OA in leaf segments, but the addition of 10 mM NO₃^– increased leaf OA by up to 81%. K⁺ and glycinebetaine were not accumulated in leaf segments exposed to WD under PEG −0.5 MPa during 48 h, but Na⁺, Cl⁻, proline and total soluble sugars accounted for up to 21, 20, 7 and 40% of OA, respectively. Total soluble sugars were the largest contributor to OA and may also contribute to membrane stability. Further data are needed on accumulation of leaf NO₃⁻ and glycinebetaine in response to increasing nitrogen supply, and on which other inorganic and organic solutes may also contribute to OA under PEG-induced WD. Laboratory experiments with leaf segments exposed to WD under −0.5 MPa PEG, and with 10 mM K⁺, Na⁺ or NO₃⁻ added to the basal solution, could provide an effective and rapid pre-screen of diverse germplasm sources for OA expression. Selected genotypes should then be validated by exposure to soil WD for agronomic evaluation, and for OA expression under field WD.

GRAPHICAL ABSTRACT

KEYWORDS:

• Glycinebetaine
• K⁺
• Na⁺
• nitrogen
• proline
• total soluble sugars

Acknowledgments

SAN received an ADS AusAID PhD scholarship. Special thanks to Dr. Tony Condon for seeds, Mr. Gunawan Wibisono, Ms. Rachel Javahar, Ms. Nadia Bazihizina and Ms. Wang Xing for help with sample collection, Mr. Greg Cawthray for HPLC analyses, Professors Hank Greenway and David Turner for critiquing the manuscript, and Professor Tim Colmer for supervision.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Abbreviations

DM	=	dry matter
FEFL	=	fully-expanded flag leaf
OA	=	osmotic adjustment
OP	=	osmotic potential
PEG	=	polyethylene glycol
RWC	=	relative water content
[Solute]	=	solute concentration
TSS	=	total soluble sugars
WC	=	water content
WD	=	water deficit.

Data availability statement

[dataset] Wade, Len (2022). Solute contributions to osmotic adjustment in leaf segments of wheat (Triticum aestivum L.) exposed to polyethylene glycol-induced water deficit. Mendeley Data, V1. http://dx.doi.org/10.17632/hm4d3pz6mb.1.