Gibberellin reverses the negative effect of paclobutrazol but not of chlorocholine chloride on the expression of SGs/GAs biosynthesis-related genes and increases the levels of relevant metabolites in Stevia rebaudiana

• Published in: Plant cell, tissue and organ culture Vol. 146; no. 1; pp. 171 - 184
• Main Authors: Lucho, Simone Ribeiro, do Amaral, Marcelo Nogueira, Milech, Cristini, Bianchi, Valmor João, Almagro, Lorena, Ferrer, María Ángeles, Calderón, Antonio Asensio, Braga, Eugenia Jacira Bolacel
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01.07.2021; Springer Nature B.V
• Subjects: Biomedical and Life Sciences; Biosynthesis; Chlorides; Explants; Feedback loops; Genes; Gibberellic acid; Gibberellins; Growth regulators; Initial conditions; Life Sciences; Metabolites; Original Article; Parameter identification; Phenolic compounds; Phenols; Plant Genetics and Genomics; Plant growth; Plant Pathology; Plant Physiology; Plant Sciences; Stevia rebaudiana; Steviol glycosides; Stevioside; Biosynthesis inhibitors; Gibberellic acid; Specialised metabolites; Transcriptional regulation; Stevia; Morphological traits
• ISSN: 0167-6857; 1573-5044
• DOI: 10.1007/s11240-021-02059-6

Steviol glycosides (SGs) and gibberellins (GAs) share the same molecular basis. However, the coordination of their respective biosynthetic pathways is very intriguing. Thus, the present study aimed to investigate the role of plant growth regulators, gibberellic acid (GA 3 ), chlorocholine chloride (CCC), and paclobutrazol (PBZ), on the metabolism of Stevia rebaudiana and identify possible ameliorates of the evaluated parameters when CCC and PBZ-treated plants were subsequently treated with GA 3 . For this, explants were cultured in the absence or presence of 2 mg L −1 GA 3 , CCC, or PBZ (Step 1). After 20 days, half explants incubated with CCC and PBZ were treated with 2 mg L −1 GA 3 and the other half, as well as the rest of the explants, were sub-cultured in their respective initial conditions for 20 days (Step 2). GA 3 -treated plants showed increased stevioside and phenolic compounds content, as well as a downregulation of most of the SGs/GAs biosynthesis-related genes, with a more pronounced effect upstream of steviol. Following this trend, CCC downregulated some MEP pathway genes, including SrDXS, SrDXR, SrCDPS , and SrKS , and upregulated SrUGT6G1 . PBZ also upregulated SrUGT76G1 and inhibited five genes of the MEP pathway and all genes coding for kaurenoid pathway enzymes. The obtained results highlight the capability of GA 3 to reverse the negative effects of PBZ on the pattern of many transcripts and to additionally increase the stevioside content to levels comparable to those found in field-grown plants. Graphic abstract Key message A feedback loop in in vitro cultured stevia plants in response to GA3, CCC and PBZ was demonstrated. GA3-treated plants showed increases in stevioside and phenolic compound contents.