Comparison of sucrose metabolism in wheat seedlings during drought stress and subsequent recovery

Sucrose is a dominant sugar transported to the sink organs of a plant where it is metabolized to other compounds or stored. Here, the importance of sucrose metabolism in a drought-tolerant wheat cultivar was compared to a drought-sensitive one. The 4-d-old Triticum aestivum L. seedlings were exposed to drought induced by water cessation for 7 d and recovery after re-watering for further 7 d. Under control conditions, constitutive expression of genes encoding vacuolar invertase (VI) and sucrose synthase (SuS) and activity of sucrose phosphate synthase (SPS) were significantly higher in the tolerant cultivar than in the sensitive one. Drought promoted the expressions of SPS and VI genes in the tolerant cultivar and increased their activities to 175 and 132 %, respectively, of those under control conditions. The activity of SuS and expression of its gene, however, were identical in both cultivars under drought stress. These changes resulted in more remarkable accumulation of sucrose in tolerant than in sensitive cultivar under water stress.