Physiological and biochemical tools useful in drought-tolerance detection in genotypes of winter triticale: accumulation of ferulic acid correlates with drought tolerance

Abstract

Background and aims: The objectives of this study were to investigate whether a classification of triticale genotypes into drought-tolerant and drought-sensitive types based on field performance trials correlates with a classification based on measurements of some physiological and biochemical parameters in greenhouse conditions. In addition, an examination was carried out of whether ferulic acid, as the main origin of the blue fluorescence produced, contributes to drought tolerance.

Methods: Ten winter triticale genotypes were examined, five known to be drought tolerant and five drought sensitive. Measurements of the osmotic potential, leaf gas exchange, chlorophyll fluorescence, and blue and red fluorescence were performed. In addition, analysis of the total pool of phenolic compounds and ferulic acid as well as the measurements of PAL (l-phenylalanine ammonia-lyase) activity were carried out.

Key results: In agreement with field trials, three out of five cultivars ('Lamberto', 'Timbo' and 'Piano') were classified as drought tolerant. However, in the case of cultivar 'Babor', included in the group of drought-sensitive cultivars, the values obtained for some measured parameters were close to (F(v)(')/F(m)('), phenolics content, osmotic potential) or even better than (non-photochemical quenching, red and blue fluorescence, ferulic acid content) those for drought-tolerant genotypes. Cultivars 'Imperial', 'Ticino', 'Trimaran' and 'Boreas' were included in the drought-sensitive group, whereas cultivars 'Focus' and 'Kitaro' were included in the moderately sensitive group.

Conclusions: The experiments confirmed that the period of flowering, the critical phase for plants as far as water demand is concerned, is suitable for plant screening and differentiation due to their tolerance to drought. The most important criteria which enabled creation of the ranking list of plants, from those sensitive to drought to those tolerant to drought, were the ability to perform the process of osmoregulation, the efficiency of the utilization of excitation energy by the photosynthetic apparatus and the functioning of protective mechanisms involving the level of ferulic acid in leaf tissues.

Fig. 1.

Effect of drought treatment on the leaf osmotic potential (Ψ_o) of winter triticale genotypes. Data are means ± s.e. of five replicates.

Fig. 2.

Correlations between photosynthesis rate (A), transpiration rate (B) and osmotic potential (Ψ_o) for drought-treated genotypes of winter triticale.

Fig. 3.

Effect of drought treatment on the maximal efficiency of PSII photochemistry (F_v/F_m) of winter triticale genotypes. Data are means ± s.e. of five replicates.

Fig. 4.

Correlations between (A) actual fluorescence (F_v^′/F_m^′ ), (B) photochemical quenching coefficient (QP), (C) non-photochemical quenching coefficient (NQP), (D) quantum efficiency of PSII (Φ_PSII) and osmotic potential (Ψ_o) for drought-treated genotypes of winter triticale.

Fig. 5.

Effect of drought treatment on the electron transport rate (ETR) of winter triticale genotypes. Data are means ± s.e. of five replicates.

Fig. 6.

Correlations between (A) actual fluorescence (F_v^′/F_m^′), (B) photochemical quenching coefficient (QP), (C) non-photochemical quenching coefficient (NQP), (D) quantum efficiency of PSII (Φ_PSII), (E) electron transport rate (ETR) and photosynthesis rate for drought-treated genotypes of winter triticale.

Fig. 7.

Correlations between (A) emission of red fluorescence, (B) emission of far-red fluorescence and osmotic potential (Ψ_o) for drought-treated genotypes of winter triticale.

Fig. 8.

Correlations between (A) emission of red fluorescence, (B) emission of far-red fluorescence and non-photochemical quenching coefficient (NQP) for drought-treated genotypes of winter triticale.

Fig. 9.

Correlation between emission of blue fluorescence and osmotic potential of drought-treated genotypes of winter triticale.

Fig. 10.

Correlations between (A) ferulic acid content and osmotic potential and (B) emission of blue fluorescence and ferulic acid content for drought-treated genotypes of winter triticale.