Salinity Tolerance in a Synthetic Allotetraploid Wheat (SSAA) Is Similar to Its Higher Tolerant Parent (SS) and Linked to Flavonoids Metabolism.

Allotetraploidization between A and S (closely related to B) genome species led to the speciation of allotetraploid wheat (genome BBAA). However, the immediate metabolic outcomes and adaptive changes caused by the allotetraploidization event are poorly understood. Here, we investigated how allotetraploidization affected salinity tolerance using a synthetic allotetraploid wheat line (genome SSAA, labeled as 4x), its (genome SS, labeled as SS) and (AA genome, labeled as AA) parents. We found that the degree of salinity tolerance of 4x was similar to its SS parent, and both were substantially more tolerant to salinity stress than AA. This suggests that the SS subgenome exerts a dominant effect for this trait in 4x. Compared with SS and 4x, the salinity-stressed AA plants did not accumulate a higher concentration of Na in leaves, but showed severe membrane peroxidation and accumulated a higher concentration of ROS (HO and O ) and a lesser concentration of flavonoids, indicating that ROS metabolism plays a key role in saline sensitivity. Exogenous flavonoid application to roots of AA plants significantly relieved salinity-caused injury. Our results suggest that the higher accumulation of flavonoids in SS may contribute to ROS scavenging and salinity tolerance, and these physiological properties were stably inherited by the nascent allotetraploid SSAA.