Evidence for the direct 2beta- and 3beta-hydroxylation of [2H2]GA20-13-O-[6'-2H2]glucoside in seedlings of Phaseolus coccineus

Advancing Glucose Conjugated Gibberellins Discovery: A Structure-Oriented Screening and Identification Method for Unraveling Gibberellin Metabolites in Plants

Gibberellins (GAs) play a pivotal role in modulating plant growth and development. Glucose-conjugated gibberellins (Glc-GAs), a prevalent conjugated form of GAs, regulate intracellular GA levels by the coupling and decoupling of glucose groups. However, the diversity of Glc-GAs identified within individual species remains limited, hinting at a multitude of yet undiscovered gibberellin metabolites. This lacuna poses considerable impediments to research efforts dedicated to comprehensively delineating the GA metabolic pathway. In this study, we developed a structure-oriented screening and identification method for Glc-GAs in plant species by employing LC-MS/MS coupled with chemical derivatization. Through the application of chemical derivatization technique, carboxyl groups on Glc-GAs were labeled which effectively enhanced the sensitivity and selectivity of mass spectrometry detection for these compounds. Concurrently, the integration of mass spectrometry fragmentation and chromatographic retention behavior facilitated the efficient screening and identification of potential Glc-GAs. With this strategy, we screened and identified 12 potential Glc-GAs from six plant species. These findings expand the Glc-GA diversity in plants and contribute to understanding GA metabolic pathways.

Conjugates of abscisic acid, brassinosteroids, ethylene, gibberellins, and jasmonates

Phytohormones, including auxins, abscisic acid, brassinosteroids, cytokinins, ethylene, gibberellins, and jasmonates, are involved in all aspects of plant growth, and developmental processes as well as environmental responses. However, our understanding of hormonal homeostasis is far from complete. Phytohormone conjugation is considered as a part of the mechanism to control cellular levels of these compounds. Active phytohormones are changed into multiple forms by acylation, esterification or glycosylation, for example. It seems that conjugated compounds could serve as pool of inactive phytohormones that can be converted to active forms by de-conjugation reactions. Some conjugates are thought to be temporary storage forms, from which free active hormones can be released after hydrolysis. It is also believed that conjugation serves functions, such as irreversible inactivation, transport, compartmentalization, and protection against degradation. The nature of abscisic acid, brassinosteroid, ethylene, gibberellin, and jasmonate conjugates is discussed.