Different allocation of carbohydrates and phenolics in dehydrated leaves of triticale

Abstract

Carbohydrates are used in plant growth processes, osmotic regulation and secondary metabolism. A study of the allocation of carbohydrates to a target set of metabolites during triticale acclimation to soil drought was performed. The study included a semi-dwarf cultivar 'Woltario' and a long-stemmed cultivar 'Moderato', differing in the activity of the photosynthetic apparatus under optimum growth conditions. Differences were found in the quantitative and qualitative composition of individual carbohydrates and phenolic compounds, depending on the developmental stage and water availability. Soluble carbohydrates in the semi-dwarf 'Woltario' cv. under soil drought were utilized for synthesis of starch, soluble phenolic compounds and an accumulation of cell wall carbohydrates. In the typical 'Moderato' cv., soluble carbohydrates were primarily used for the synthesis of phenolic compounds that were then incorporated into cell wall structures. Increased content of cell wall-bound phenolics in 'Moderato' cv. improved the cell wall tightness and reduced the rate of leaf water loss. In 'Woltario' cv., the increase in cell osmotic potential due to an enhanced concentration of carbohydrates and proline was insufficient to slow down the rate of leaf water loss. The mechanism of cell wall tightening in response to leaf desiccation may be the main key in the process of triticale acclimation to soil drought.

Keywords: Cell wall carbohydrates; Cell wall-bound phenolics; Drought stress; Soluble carbohydrates; Soluble phenolics; Starch.