Gibberellins regulate the stem elongation rate without affecting the mature plant height of a quick development mutant of winter wheat (Triticum aestivum L.).

Gibberellin (GA) is essential for determining plant height. Alteration of GA content or GA signaling results in a dwarf or slender phenotype. Here, we characterized a novel wheat mutant, quick development (qd), in which GA regulates stem elongation but does not affect mature plant height. qd and wild-type plants did not exhibit phenotypic differences at the seedling stage. From jointing to heading stage, qd plants were taller than wild-type plants due to elongated cells. However, wild-type and qd plants were the same height at heading. Unlike wild-type plants, qd plants were sensitive to exogenous GA due to mutation of Rht-B1. With continuous GA stimulation, qd seedlings and adult plants were taller than wild-type. Thus, the GA content of qd plants might differ from that of wild-type during the growth process. Analysis of GA biosynthetic gene expression verified this hypothesis and showed that TaKAO, which is involved in catalyzing the early steps of GA biosynthesis, was differentially expressed in qd plants compared with wild-type. The bioactive GA associated gene TaGA20ox was downregulated in qd plants during the late growth stages. Measurements of endogenous GA content were consistent with the gene-expression analysis results. Consistent with the GA content variation, the first three basal internodes were longer and the last two internodes were shorter in qd than in wild-type plants. The qd mutant might be useful in dissecting the mechanism by which GA regulates stem-growing process, and it may be serve as a GA responsive semi-dwarf germplasm in breeding programs.

Elucidation of in vitro phase I metabolites of droperidol using UPLC-QTOF MS.

Droperidol, an antidopaminergic drug clinically used as an antiemetic and antipsychotic, has been reported to induce cardiac toxicity in patients. Due to the close relationship between drug metabolism and efficiency and toxicity, the present study aims to investigate the phase I metabolites using ultra-performance liquid chromatography-quadrupole time-of-flight mass spectrometry. The NADPH-supplemented phase I incubation system was used to elucidate the in vitro phase I metabolites. Five metabolites were detected after droperidol was incubated with phase I incubation mixture, including one hydrogenated droperidol, three oxidative metabolites, and one N-dealkylated droperidol, elucidated by individual retention time and MS/MS fragmentation. Due to the existed phase II metabolic reaction, further phase II metabolism should be investigated in the future. In conclusion, the phase I metabolism of droperidol was investigated in the present study, and five new metabolites were identified. The efficiency and toxicity of these phase I metabolites should be investigated in the future.