Journal of Plant Physiology 169 (2012) 1728–1736 Contents lists available at SciVerse ScienceDirect Journal of Plant Physiology j ourna l ho mepage: www.elsevier.de/jplph An increase in the content of cell wall-bound phenolics correlates with the productivity of triticale under soil drought Tomasz Hura a,∗ , Katarzyna Hura b , Kinga Dziurka a , Agnieszka Ostrowska a , Renata B˛ aczek-Kwinta b , Maciej Grzesiak a a The Franciszek Górski Institute of Plant Physiology, Polish Academy of Sciences, Niezapominajek 21, 30-239 Kraków, Poland b Department of Plant Physiology, Faculty of Agriculture and Economics, Agricultural University, Podlu ˙ zna 3, 30-239 Kraków, Poland a r t i c l e i n f o Article history: Received 12 March 2012 Received in revised form 29 June 2012 Accepted 2 July 2012 Keywords: Phenolics Soil drought Plant biomass Yield Water status a b s t r a c t The objective of this study was to investigate whether the content of cell wall-bound phenolics can simultaneously influence both the productivity and the water status of triticale under soil drought con- ditions. Two parallel treatments were carried out. The T1 treatment involved plants being subjected to soil drought twice, during the tillering phase and then during the flowering phase. The T2 treatment included drought only during the flowering phase. After T1 treatment, the majority of cultivars exhibited better PSII functioning at the flowering phase in comparison to T2, which could be related to better adaptation of the photosynthetic apparatus to leaf dehydration. Simultaneously, the higher activity of the photosynthetic apparatus of flag leaves for T1 was significantly correlated with the higher content of cell wall-bound phenolics. The dry mass of plants was markedly lower in the T1 treatment and was correlated with a higher content of cell wall-bound phenolics. Moreover, cultivars subjected to the T1 treatment showed a significantly higher water content in comparison to the T2 treatment. The delay in the leaf rolling and the ageing of plants in the T1 treatment, which induced a higher level of cell wall-bound phenolics, was visual proof of the improvement in the water status of plants. Phenolic compounds that form cross-bridges with carbohydrates of the cell wall can be considered a more effective biochemical protective mechanism than free phenolics during the dehydration of leaves. This potentially higher level of effectiveness is likely the result of the double action of phenolic com- pounds, both as photoprotectors of the photosynthetic apparatus and hydrophobic stabilizers, preventing water loss from the apoplast. © 2012 Elsevier GmbH. All rights reserved. Introduction Soil drought is a vital, and at the same time unpredictable, environmental factor influencing crop production (Wu and Wang, 2000; Wardlaw, 2002). The leaf dehydration induced by soil water deficit leads to disorders in biochemical and physiological pro- cesses constituting the base of plant productivity (Souza et al., 2004). However, it should be stressed that the negative effects of drought stress can be reduced, depending on the genotype, by trigg- ering adaptive mechanisms (Abernethy and McManus, 1998; Hura et al., 2007a, 2009b; Varone et al., 2012). Among the plant phenolics that are integral components of the cell walls, covalent cross-bonds, mainly of an ester- and ether- type, between neighboring polycarbohydrate chains (e.g. between hemicelluloses and/or pectin chains), are biosynthesized in consid- erable amounts (Strack, 1997; Vogt, 2010). The accumulation of cell ∗ Corresponding author. Tel.: +48 012 425 33 01; fax: +48 012 425 32 20. E-mail address: t.hura@ifr-pan.krakow.pl (T. Hura). wall-bound phenolics is often observed as a consequence of the impact of environmental stresses (Reuber et al., 1996; Schultheiss et al., 2002; Hura et al., 2011). However, higher activity in the synthesis pathway of free phenolics and a significant role of solu- ble phenylpropanoids in drought stress tolerance have been found (Hura et al., 2007a; Sánchez-Rodríguez et al., 2010, 2011). In earlier work concerning the influence of water stress applied during the vegetative phase of triticale growth, an increase in the content of cell wall-bound ferulic acid (belonging to phenylpropanoids) was shown in the variety that was drought resistant. Moreover, it was correlated simultaneously with a decrease in the dry mass of leaves (Hura et al., 2009a). This observed dependence led to an assumption that cell wall-bound phenolics could, in drought conditions, influ- ence a plants productivity manifested, among others, as the activity of the photosynthetic apparatus or through changes in plant biomass and grain yield. In studies, not concerning drought stress, it was shown that an increase in the content of cell wall-bound phenolics is a ‘chemical barrier’, which can slow the utilization of carbohydrates as building materials in the cell wall structures (Fry, 1979, 1982). 0176-1617/$ – see front matter © 2012 Elsevier GmbH. All rights reserved. http://dx.doi.org/10.1016/j.jplph.2012.07.012