Fusarium solani Upregulated Sesquiterpene Synthase Expression,Sesquiterpene Production and Allelopathic Activity in Piper betle L.

Activators of sesquiterpene synthase (STS) gene expression and sesquiterpene production in Piper betle L. were examined using quantitative real time PCR and gas chromatography mass spectrometry methods, and the allelopathic activity of untreated and Fusarium solani-treated betel extracts was tested on seed germination and on the shoot and root growth of Thai rice variety PSL2 (Oryza sativa cv. Phitsanulok 2) and three dominant paddy weeds (Eclipta prostrata, Echinochloa crus-galli and Chloris barbata). The results demonstrated that F. solani dramatically upregulated STS expression and productions of β-cubebene, β-caryophyllene and germacrene D sesquiterpene when compared with the untreated control, and that betel extracts had a greater inhibitory effect on weeds than on rice. The effects were more clearly detected on seed germination and root growth than on shoot growth, and they were found to be dose-dependent. It is also noted that F. solani-treated extract had stronger effects than the untreated extract. The species most sensitive to the allelopathic effects was C. barbata, germination of which was completely inhibited even at a dose of 0.1 mg/mL untreated extract. With regards to rice, although betel extract at 1.0 mg/mL showed no inhibition on germination, it affected the elongation of rice roots, in addition to those of the tested weeds. The obtained data suggested that F. solani has potential as an activator of sesquiterpene allelochemical production via STS expression, the latter leading to the treated betel extract having a stronger phytotoxic effect. These results were beneficial in the promotion of natural herbicide production using biotechnology.     

Improved shoot regeneration from nodules of Charybdis numidica in a temporary immersion system

Summary

A procedure for improved shoot regeneration from meristematic nodules of Charybdis numidica in a temporary immersion culture system was developed by optimizing immersion frequencies, volume of the nutrient medium, and alternating application of growth regulators. Modified liquid MS medium with 3% sucrose, 20 μM BAP and 5 μM NAA (shoot induction medium) was used to induce microshoot formation on 15 g of nodules in 1000 ml bottles. Volumes of medium (250 or 500 ml) and immersion frequency (5 min every 12 or 24 h) did not significantly influence shoot regeneration rates. Shoot induction medium additionally supplemented with 5 μM paclobutrazol in most cases led to less shoots but this effect was not significant, either. Microshoots formed under these conditions were severely hyperhydrated. Nearly complete elimination of hyperhydricity and enhanced formation of properly elongated shoots were achieved by running a shoot induction step with induction medium containing paclobutrazol followed by an elongation step with a medium supplemented only with 5 μM gibberellic acid GA₃. This two-step procedure yielded about 900 healthy shoots per bottle after a two-month cultivation period. Root induction was performed ex vitro during acclimatization and the plantlets could be established in the greenhouse with good success.     

Fusarium solani Upregulated Sesquiterpene Synthase Expression,Sesquiterpene Production and Allelopathic Activity in Piper betle

Activators of sesquiterpene synthase(STS) gene expression and sesquiterpene production in Piper betle L. were examined using quantitative real time PCR and gas chromatography mass spectrometry methods, and the allelopathic activity of untreated and Fusarium solani-treated betel extracts was tested on seed germination and on the shoot and root growth of Thai rice variety PSL2(Oryza sativa cv. Phitsanulok 2) and three dominant paddy weeds(Eclipta prostrata, Echinochloa crus-galli and Chloris barbata). The results demonstrated that F. solani dramatically upregulated STS expression and productions of ?-cubebene, β-caryophyllene and germacrene D sesquiterpene when compared with the untreated control, and that betel extracts had a greater inhibitory effect on weeds than on rice. The effects were more clearly detected on seed germination and root growth than on shoot growth, and they were found to be dose-dependent. It is also noted that F. solani-treated extract had stronger effects than the untreated extract. The species most sensitive to the allelopathic effects was C. barbata, germination of which was completely inhibited even at a dose of 0.1 mg/mL untreated extract. With regards to rice, although betel extract at 1.0 mg/mL showed no inhibition on germination, it affected the elongation of rice roots, in addition to those of the tested weeds. The obtained data suggested that F. solani has potential as an activator of sesquiterpene allelochemical production via STS expression, the latter leading to the treated betel extract having a stronger phytotoxic effect. These results were beneficial in the promotion of natural herbicide production using biotechnology.