Transfer of the barrier to radial oxygen loss in roots of Hordeum marinum to wheat (Triticum aestivum): evaluation of four H. marinum-wheat amphiploids

Wide hybridization of waterlogging-tolerant Hordeum marinum with wheat (Triticum aestivum) to produce an amphiploid might be one approach to improve waterlogging tolerance in wheat. Growth, root aerenchyma and porosity, and radial oxygen loss (ROL) along roots were measured in four H. marinum-wheat amphiploids and their parents (four accessions of H. marinum and Chinese Spring wheat) in aerated or stagnant nutrient solution. A soil experiment was also conducted. Hordeum marinum maintained shoot dry mass in stagnant nutrient solution, whereas the growth of wheat was markedly reduced (40% of aerated control). Two of the four amphiploids were more tolerant than wheat (shoot dry masses of 59-72% of aerated controls). The porosity of adventitious roots when in stagnant solution was higher in H. marinum (19-25%) and the four amphiploids (20-24%) than in wheat (16%). In stagnant solution, adventitious roots of H. marinum formed a strong ROL barrier in basal zones, whereas, in wheat, the barrier was weak. Two amphiploids formed a strong ROL barrier and two formed a moderate barrier when in stagnant solution. This study demonstrates the transfer of higher root porosity and a barrier to ROL from H. marinum to wheat through wide hybridization and the production of H. marinum-wheat amphiploids.