methyl-jasmonate and indolebutyric-acid

Indole-3-acetic acid (IAA), and its precursor indole-3-butyric acid (IBA), control adventitious root (AR) formation in planta. Adventitious roots are also crucial for propagation via cuttings. However, IBA role(s) is/are still far to be elucidated. In Arabidopsis thaliana stem cuttings, 10 μM IBA is more AR-inductive than 10 μM IAA, and, in thin cell layers (TCLs), IBA induces ARs when combined with 0.1 μM kinetin (Kin). It is unknown whether arabidopsis TCLs produce ARs under IBA alone (10 μM) or IAA alone (10 μM), and whether they contain endogenous IAA/IBA at culture onset, possibly interfering with the exogenous IBA/IAA input. Moreover, it is unknown whether an IBA-to-IAA conversion is active in TCLs, and positively affects AR formation, possibly through the activity of the nitric oxide (NO) deriving from the conversion process.. Revealed undetectable levels of both auxins at culture onset, showing that arabidopsis TCLs were optimal for investigating AR-formation under the total control of exogenous auxins. The AR-response of TCLs from various ecotypes, transgenic lines and knockout mutants was analyzed under different treatments. It was shown that ARs are better induced by IBA than IAA and IBA + Kin. IBA induced IAA-efflux (PIN1) and IAA-influx (AUX1/LAX3) genes, IAA-influx carriers activities, and expression of ANTHRANILATE SYNTHASE -alpha1 (ASA1), a gene involved in IAA-biosynthesis. ASA1 and ANTHRANILATE SYNTHASE -beta1 (ASB1), the other subunit of the same enzyme, positively affected AR-formation in the presence of exogenous IBA, because the AR-response in the TCLs of their mutant wei2wei7 was highly reduced. The AR-response of IBA-treated TCLs from ech2ibr10 mutant, blocked into IBA-to-IAA-conversion, was also strongly reduced. Nitric oxide, an IAA downstream signal and a by-product of IBA-to-IAA conversion, was early detected in IAA- and IBA-treated TCLs, but at higher levels in the latter explants.. Altogether, results showed that IBA induced AR-formation by conversion into IAA involving NO activity, and by a positive action on IAA-transport and ASA1/ASB1-mediated IAA-biosynthesis. Results are important for applications aimed to overcome rooting recalcitrance in species of economic value, but mainly for helping to understand IBA involvement in the natural process of adventitious rooting.

Topics: Acetates; Anthranilate Synthase; Arabidopsis; Arabidopsis Proteins; Cyclopentanes; Cytokinins; Indoleacetic Acids; Indoles; Membrane Transport Proteins; Nitric Oxide; Oxylipins; Plant Roots; Tissue Culture Techniques

Scutellaria lateriflora (American skullcap) has been used in traditional medicine to treat several medical conditions including nervous disorders and cancer. Previous studies have associated these medicinal properties to flavones present in roots and leaves of this species. In order to develop a production system and study the biosynthesis of these bioactive compounds, hairy root cultures of S. lateriflora were established and line 4 was selected for further studies based on its growth performance in a modified Murashige and Skoog's medium supplemented with 0.5mg/l indole-3-butyric acid. Scanning electron microscopy of the hairy roots showed a high profusion of hairs along the root. Several phenolic compounds, including verbascoside, and the flavones wogonin, baicalein, scutellarein and their respective glucuronides were identified by high performance liquid chromatography-tandem mass spectrometry in the root tissue, but not in the culture medium. Among these compounds, verbascoside accumulated at the highest levels. Interestingly, cultures incubated under continuous light and treated with 15mM methyl-β-cyclodextrin for 24h produced significantly higher levels of the aglycones, baicalein and wogonin, but not scutellarein, compared to cultures incubated under continuous darkness. This work demonstrates that hairy root cultures of S. lateriflora have the biosynthetic capacity to produce known Scutellaria flavones and suggest that light may have a selected regulatory effect on the synthesis or accumulation of these phenolic compounds.

Topics: Acetates; Chromatography, High Pressure Liquid; Cyclodextrins; Cyclopentanes; Flavanones; Glucosides; Indoles; Light; Molecular Structure; Nuclear Magnetic Resonance, Biomolecular; Oxylipins; Phenols; Plant Roots; Plants, Medicinal; Polymerase Chain Reaction; Scutellaria; Serine Endopeptidases

Adventitious roots (ARs) are induced by auxins. Jasmonic acid (JA) and methyl jasmonate (MeJA) are also plant growth regulators with many effects on development, but their role on ARs needs investigation. To this aim, we analyzed AR formation in tobacco thin cell layers (TCLs) cultured with 0.01-10 microM MeJA, either under root-inductive conditions, i.e., on medium containing 10 microM indole-3-butyric acid (IBA) and 0.1 microM kinetin, or without hormones. The explants were excised from the cultivars Samsun, Xanthii and Petite Havana, and from genotypes with altered AR-forming ability in response to auxin, namely the non-rooting rac mutant and the over-rooting Agrobacterium rhizogenes rolB transgenic line. Results show that NtRNR1 (G1/S) and Ntcyc29 (G2/M) gene activity, cell proliferation and meristemoid formation were stimulated in hormone-cultured TCLs by submicromolar MeJA concentrations. The meristemoids developed either into ARs and xylogenic nodules, or into xylogenic nodules only (rac TCLs). MeJA-induced meristemoid over-production characterized rolB TCLs. No rooting or xylogenesis occurred under hormone-free conditions, independently of MeJA and genotype. Endogenous JA progressively (days 1-4) increased in hormone-cultured TCLs in the absence of MeJA. JA levels were enhanced by 0.1 microM MeJA, on both days 1 and 4. Endogenous IBA was the only auxin detected, both in the free form and as IBA-glucose. Free IBA increased up to day 2, remaining constant thereafter (day 4). Its level was enhanced by 0.1 microM MeJA only on day 1, while IBA conjugation was not affected by MeJA. Taken together, these results show that an interplay between jasmonates and auxins regulates AR formation and xylogenesis in tobacco TCLs.

Topics: Acetates; Cells, Cultured; Cyclopentanes; Gene Expression Regulation, Plant; Indoles; Interphase; Meristem; Mitosis; Nicotiana; Oxylipins; Plant Growth Regulators; Plant Proteins; Plant Roots; Xylem

Indole-3-butyric acid at 25 microM with methyl jasmonate (MJ) at 100 microM in Panax ginseng synergistically stimulated both root growth and ginsenoside accumulation compared with 100 microM MJ alone. Productivity of ginsenoside was 10 mg l(-1) d(-1) compared to 7.3 mg l(-1) d(-1) with MJ elicitation alone.

Topics: Acetates; Bioreactors; Cell Culture Techniques; Cells, Cultured; Cyclopentanes; Ginsenosides; Indoles; Oxylipins; Panax; Plant Growth Regulators; Plant Roots; Plants, Medicinal