Yeast polysaccharide YE-2-1 promoted ingenol-3-angelate production in Euphorbia peplus cambium meristematic cell cultures.

Ingenol-3-angelate (PEP005), the main bioactive compound among the diterpenoid esters from Euphorbia peplus, has a good therapeutic effect on skin tumors. However, the supply of PEP005 still has problems with low yield. Yeast extract (YE) was selected as the elicitor to improve the contents and explore the biosynthetic pathway of PEP005 in cambial meristematic cells (CMCs) from E. peplus. A homogeneous glucomannan (YE-2-1) was isolated from YE through anion exchange chromatography and gel chromatography, which had high elicitor activity. The backbone of YE-2-1 was composed of →3)-α-D-Manp-(1→, →2,4)-α-D-Manp-(1→, →6)-α-D-Glcp-(1→, →3,6)-β-D-Glcp-(1→, →2)-α-D-Glcp-(1→, and →2,3,6)-β-D-Glcp-(1 → with five distinct side chains. This study further identified the first BAHD acyltransferase (E. peplus Bahd-at2) and a CYP71 clan cytochrome P450 (E. peplus Cyp726a6) via self-organizing map, phylogenetic tree and differential gene expression analysis between E. peplus CMCs and dedifferentiated cells. YE and YE-2-1 stimulated PEP005 biosynthetic genes including E. peplus Bahd-at2 and E. peplus Cyp726a6. Molecular docking and gene silencing results indicated that E. peplus Cyp726a6 had the potential to catalyze 20-oxidation of casbene. This work provides a basis for understanding the biosynthesis of PEP005 and new insights to use YE polysaccharide as elicitor to enhance the yield of PEP005.