Genetic variation for aerenchyma and other root anatomical traits in durum wheat (Triticum durum Desf.)

Variation in root anatomical traits influences whole plant physiology and crop adaptation to adverse soil conditions and thus impacts yield and its stability. A typical component of anatomical root traits is the arrangement of cells and tissues as observed by microscopy sections. In this study, we investigated the phenotypic variation of 11 root anatomical traits including aerenchyma-like features in ten elite durum wheat cultivars and found significant differences among cultivars for several traits. Trait heritability ranged from 0.12 (number of xylem vessels) to 0.72 (number of aerenchyma-like lacunae). While area and number of aerenchyma-like lacunae were highly correlated, neither trait correlated with other root features, suggesting an independent physiological and/or genetic control in respect to the other root anatomical traits. The old Italian founder cultivar Cappelli was shown to have a significantly higher portion of root aerenchyma-like structures of all the modern cultivars. These results show for the first time the presence of sizeable genetic variation in root anatomical traits in cultivated tetraploid wheats, prompting for additional studies aimed at mapping the quantitative trait loci governing such variation and to test their role in the adaptive response of durum wheat to abiotic stresses as related to soil conditions.