The corrected structure of depressoside, an antioxidative iridoid glucoside extracted from the flowers ofGentiana urnulaHarry Sm

SlbHLH22-Induced Hypertrophy Development Is Related to the Salt Stress Response of the GTgamma Gene in Tomatoes

Hypertrophy development induced by the overexpression of SlbHLH22 (also called SlUPA-like) was susceptible to Xanthomonas in tomatoes. Transcriptome and metabolome analyses were performed on the hypertrophy leaves of a SlbHLH22-overexpressed line (OE) and wild type (WT) to investigate the molecular mechanism. Metabolome analysis revealed that six key metabolites were over-accumulated in the OE, including Acetylserine/O-Acetyl-L-serine, Glucono-1,5-lactone, Gluconate, 2-Oxoglutarate, and Loganate, implying that the OE plants increased salt or oxidant resistance under normal growth conditions. The RNA-seq analysis showed the changed expressions of downstream genes involved in high-energy consumption, photosynthesis, and transcription regulation in OE lines, and we hypothesized that these biological processes were related to the GTgamma subfamily of trihelix factors. The RT-PCR results showed that the expressions of the GTgamma genes in tomatoes, i.e., SlGT-7 and SlGT-36, were suppressed in the hypertrophy development. The expression of the GTgamma gene was downregulated by salinity, indicating a coordinated role of GTgamma in hypertrophy development and salt stress. Further research showed that both SlGT-7 and SlGT-36 were highly expressed in leaves and could be significantly induced by abscisic acid (ABA). The GTgamma protein had a putative phosphorylation site at S96. These results suggested GTgamma's role in hypertrophy development by increasing the salt resistance.

Iridoid glycosides from the Genus Gentiana (Gentianaceae) and their Chemotaxonomic Sense

The genus Gentiana is one of the largest genera in the Gentianaceae family. Many Gentiana species have been scientifically investigated for their chemical constituents and chemotaxonomic sense. To date, more than 500 chemical compounds were isolated from Gentiana plant. Several researchers have reviewed the secondary metabolites and their bioactivities of Gentiana plants. However, a survey on iridoid glycosides and their chemotaxonomic sense of the genus Gentiana are unavailable. Iridoid glycosides are the major chemicals isolated from Gentiana spp., which serve as potential chemotaxonomic markers to differentiate Gentiana species. Herein, the review systematically summarizes the scaffolds of the iridoids reported according to the biosynthetic pathway of natural iridoid glycosides. Furthermore, the taxonomy of Gentiana and chemotaxonomic sense of iridoid glycosides in the genus Gentiana were surveyed.