Comparative analyses of alterations in carbohydrates, amino acids, phenols and lignin in roots of three cultivars of Xanthosoma sagittifolium infected by Pythium myriotylum

Abstract

The putative role of carbohydrates, amino acids, phenols and lignin in the susceptibility of Xanthosoma sagittifolium to Pythium myriotylum root rot disease was investigated by comparing the alterations of these groups of molecules in the roots of the white (susceptible), red (tolerant) and yellow (resistant) cultivars. At Day 8 after inoculation, total soluble sugars decreased. There was a positive correlation between this decrease and the root rot disease index for the white, the red and the yellow cultivars. At Day 2 proline was no longer detected in the yellow cultivar, while its content was 83% and 84% of the initial values in the white and red cultivars, respectively. At the same time, total amino acid content increased in the three cultivars. However, this increase was negatively correlated to the disease only in the yellow cultivar (rp = 0.940, P