ABSTRACT
Methyl jasmonate (MeJA) is a known elicitor of plant specialized metabolism, including triterpenoid saponins. Saponaria vaccaria is an annual herb used in traditional Chinese medicine, containing large quantities of oleanane-type triterpenoid saponins with anticancer properties and structural similarities to the vaccine adjuvant QS-21. Leveraging the MeJA-elicited saponin biosynthesis, we identify multiple enzymes catalyzing the oxidation and glycosylation of triterpenoids in S. vaccaria. This exploration is aided by Pacbio full-length transcriptome sequencing and gene expression analysis. A cellulose synthase-like enzyme can not only glucuronidate triterpenoid aglycones but also alter the product profile of a cytochrome P450 monooxygenase via preference for the aldehyde intermediate. Furthermore, the discovery of a UDP-glucose 4,6-dehydratase and a UDP-4-keto-6-deoxy-glucose reductase reveals the biosynthetic pathway for the rare nucleotide sugar UDP-D-fucose, a likely sugar donor for fucosylation of plant natural products. Our work enables the production and optimization of high-value saponins in microorganisms and plants through synthetic biology approaches.
Subject(s)
Saponaria , Saponins , Triterpenes , Vaccaria , Triterpenes/metabolism , Transcriptome , Saponaria/genetics , Saponaria/metabolism , Vaccaria/genetics , Plants/metabolism , Uridine Diphosphate , Glucose , SugarsABSTRACT
The production of doubled haploid (DH) plants from microspores is an important technique used in plant breeding and basic research. DH technology is a rapid method for developing homozygous lines, which can be used to accelerate crop improvement programs. Haploidy technology can also be used in mutagenesis, transformation, and basic research such as genomic, biochemical, and physiological studies. There is no general protocol that will result in the production of DH in all species, as differences occur among species and among genotypes within a species in terms of embryogenic response. Here we describe methodology for developing doubled haploids in cow cockle (Saponaria vaccaria L.).
