Identification and characterization of some putative genes involved in arabinoxylan biosynthesis in Plantago ovata.

Plantago ovata is an important source of Psyllium (Isabgol), which swells upon contact with water forming mucilaginous mass, largely composed of arabinoxylans. In this study, we analyzed the expression pattern of arabinoxylan biosynthetic pathway genes at different stages of seed development in P. ovata. Besides, arabinoxylans were quantified at different stages of seed development in water extractable and water unextractable fractions. The expression analysis revealed 5-8 fold increase in the levels of expression of some genes involved in arabinoxylan biosynthetic pathway such as UDP-arabinopyranose mutase, UDP-xylosyltransferase 2 and xylan glucuronosyltransferase at 15 days after pollination stage in seed. The xylose and arabinose units were analyzed at different stages of seed development and also in water-soluble (cold water and hot water), alkali and ethanolic fractions. The concentration of xylose and arabinose units increased steadily after pollination. Overall, alkali extract had high concentration of xylose (0.70 ± 0.022 mg/g) and arabinose units (0.10 ± 0.01 mg/g) at 15 days after pollination stage.