Abstract
The metabolic re-arrangements of peas (Pisum sativum L.) under soil drought and re-watering are still not fully explained. The search for metabolic markers of the stress response is important in breeding programs, to allow for the selection drought-resistant cultivars. During the present study, changes in the polar metabolite content in pea plant shoots were measured under repeated short-term soil drought and subsequent re-watering. A gas chromatograph, equipped with a mass spectrometer (GC-MS), was used for the metabolite profiling of pea plants during their middle stage of vegetation (14–34 days after sowing, DAS). The major changes occurred in the concentration of amino acids and some soluble carbohydrates. Among them, proline, γ-aminobutyric acid (GABA), branched-chain amino acids, hydroxyproline, serine, myo-inositol, and raffinose were accumulated under each soil drought and decreased after re-watering. Besides, the obtained results show that the first drought/re-watering cycle increased the ability of pea plants to restore a metabolic profile similar to the control after the second similar stress. The accumulation of proline seems to be an important part of drought memory in pea plants. However, confirmation of this suggestion requires metabolite profiling studies on a broader spectrum of pea cultivars.
Highlights
The predicted further global temperature increase in the 21st century, together with the disruption of water retention in soils, increases the risk of both periodic droughts and the successive desertification of crop fields [1,2,3]
The fresh weight (FW) of the plants increased more than threefold, and three new nodes with leaves developed, while the shoot reached a height of about 20–25 cm at 34 days after sowing (DAS) (Figures 1 and 2)
The present study showed that the increase in the GABA level after the first period of drought was accompanied by a decrease in the level of its precursors, which are 2-keto-Dglutaric acid and glutamic acid (Table 1)
Summary
The predicted further global temperature increase in the 21st century, together with the disruption of water retention in soils, increases the risk of both periodic droughts and the successive desertification of crop fields [1,2,3]. Water stress occurs especially in the absence of precipitation and increased temperature, as well as stronger winds, which increases evaporation [6]. This leads to a deficit between water uptake by the roots and water loss by the aboveground parts of the plant. The osmotic potential of the cells increases, which inhibits further water loss and allows the roots to continue the uptake of water from the soil This osmotic adjustment is the primary defense mechanism of plants in response to water deficit [9,10]
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