Abstract: Exploring the allocation of non-structural carbohydrates (NSCs) in different organs under drought-rehydration conditions is of great significance to reveal the physiological mechanisms of drought resistance of desert plants. Two-year-old resurrection Reaumuria soongorica was grown in pots under four drought severity levels (no drought, mild, moderate, and severe drought) and four drought durations (15, 30, 45, 60 days). All seedlings were well-watered for 15 days after drought stress. The changes of NSCs in different organs under drought stresses and after rewatering were examined. The results showed that: (1) NSCs content increased with drought duration. Sucrose and glucose contents in aboveground and belowground organs were significantly higher in stressed seedlings than those without stress after 60 and 30 days of drought, respectively. (2) Translocation of NSCs occurred among organs as the drought progress. The soluble sugar was translocated between stems and leaves (after 0-30 days drought). The soluble sugar was converted into starch and stored in leaves and roots (after 30-45 days). Starch in leaves and roots was converted into soluble sugar and translocated to each organ (after 45-60 days). (3) After rehydration, the content of each NSC component decreased. The recovery indices of leaf and stem were greater than those of coarse and fine roots. The recovery indices of sucrose and fructose were greater under mild stress, while those of glucose, soluble sugar, and starch were greater under severe stress. In summary, R. soongorica improved drought resistance by increasing NSCs under drought stress, and root was the preferential sensory organ for drought signals. R. soongorica further improved drought resistance by regulating the conversion between soluble sugar and starch in different drought periods. After rehydration, various organs of R. soongorica seedlings recovered to different degrees to repair the mechanical damage caused by drought, and improved drought resistance.

Key words: drought, rehydration, Reaumuria soongorica, monosaccharide, non-structural carbohydrate