Morphological, physiochemical and antioxidant responses of Maclura pomifera to drought stress

Abstract

Drought is one of the most important environmental factor limiting the growth of woody and non woody plants. In the present paper, we aimed to explore the performance of Maclura pomifera under a prolonged drought period followed by re-watering. M. pomifera plants were exposed to four different watering regimes (100%, 75%, 50% and 30% of the field capacity (FC)) for three weeks and then rewatered. The exposure to drought affected physiological, morphological and biochemical traits of M. pomifera. Leaf area, relative water content and water potential of leaf decreased in parallel with increased water deficit. Malondialdehyde content increased along with the drought stress experiment. Soluble carbohydrates (sucrose, glucose and fructose) accumulated during drought stress, but decreased after 22 days of water deficit in severe stressed plants (30% FC). Proline and mannitol, two compatible osmolytes, were higher in drought stresses plants than in control plants. Additionally the activity of antioxidant enzymes (SOD, APX, DHAR and GR) resulted affected by drought stress. In the recovery period, the physiological parameters as well as the proline content recovered at control levels, whereas soluble sugars, mannitol and total activity of antioxidant enzymes remained slight higher than in control plants, presumably to allow plants a complete recovery after stress. Our results suggest that M. pomifera has a good adaptive response to drought stress, probably corresponded to decreasing oxidative injury by induction of the antioxidant system and accumulation of stable and protective osmolytes such as proline and mannitol at higher rates.

Figure 1

Leaf rolling of M. pomifera saplings under control (100% FC) (a), moderate (50% FC) (b) and severe (30% FC) (c).

Figure 2

Left: Leaf abscission and yellowing observed under severe drought stress (30% FC); Right: new adaptive leaves re-sprouted by 18-d of drought stress in plants under severe drought stress (30% FC).

Figure 3

The effect of drought stress treatments on RWC and leaf water potential (Ψ_WP) in leaves of M. pomifera. Data represents the average of three replicates. Vertical bars indicate ± SE. Values sharing a common letter are not significantly different at p < 0.01.

Figure 4

The effect of drought stress treatments on lipid peroxidation (MDA content) in leaves of M. pomifera. Data represents the average of three replicates. Vertical bars indicate ± SE. Values sharing a common letter are not significantly different at p < 0.01.

Figure 5

The effect of drought stress treatments on proline content in leaves of M. pomifera. Data represents the average of three replicates. Vertical bars indicate ± SE. Values sharing a common letter are not significantly different at p < 0.01.

Figure 6

The effect of drought stress treatments on sucrose (A), glucose (B), fructose (C) and mannitol (D) concentrations in leaves of M. pomifera. Data represents the average of three replicates. Vertical bars indicate ± SE. Values sharing a common letter are not significantly different at p < 0.01.

Figure 7

The effect of drought stress treatments on SOD (A), APX (B), DHAR (C) and GR (D) activities in leaves of M. pomifera. Data represents the average of three replicates. Vertical bars indicate ± SE. Values sharing a common letter are not significantly different at p < 0.01.