In vitro production of atractylon and β-eudesmol from Atractylodes chinensis by adventitious root culture

Efficacy of rhizobacteria Paenibacillus polymyxa SY42 for the biological control of Atractylodes chinensis root rot

Atractylodes chinensis is one of the most commonly used bulk herbs in East Asia; however, root rot can seriously affect its quality and yields. In contrast to chemical pesticides, biological control strategies are environmentally compatible and safe. For this study, 68 antagonistic bacterial strains were isolated from the rhizospheres of healthy Atractylodes chinensis. Strain SY42 exhibited the most potent fungicidal activities, with inhibition rates against F. oxysporum, F. solani, and F. redolens of 67.07 %, 63.40 % and 68.45 %, respectively. Through morphological observation and molecular characterization, strain SY42 was identified as Paenibacillus polymyxa. The volatile organic components (VOCs) produced by SY42 effectively inhibited the mycelial growth of pathogenic fungi through diffusion. SY42 significantly inhibited the germination of pathogenic fungal spores. Following co-culturing with SY42, the mycelium of the pathogenic fungus was deformed, folded, and even ruptured. SY42 could produce cellulases and proteases to degrade fungal cell walls. Pot experiments demonstrated the excellent biocontrol efficacy of SY42. This study revealed that P. polymyxa SY42 inhibited pathogenic fungi through multiple mechanisms, which verified its utility as a biocontrol agent for the control of A. chinensis root rot.

Adventitious root culture of Lessertia frutescens for the production of triterpenoid saponins and polysaccharides

Lessertia frutescens is a perennial shrub of commercial importance in South Africa, but the scarcity of plant resources has limited current product production. In this study, to provide an alternative approach for obtaining L. frutescens material, adventitious roots (ARs) were induced from sterilized seedlings and cultured in a suspension culture system. During this process, selection tests were conducted to find a suitable auxin and its concentration for AR induction and a suitable basal medium for AR growth and metabolite accumulation; a kinetic study was then performed to constructure kinetic models. The results showed that compared to other auxins and concentrations, indole-3-butyric acid at 3 mg/L was suitable for increasing the number and length of ARs during AR induction. In AR suspension culture, Schenk and Hildebrandt (SH) was better than other basal media, and the maximum AR fresh (86.9 g/L) or dry weight (5.5 g/L), total triterpenoid saponin (92.6 mg/g DW), and polysaccharide (114.7 mg/g DW) contents were determined in the 1.5×SH medium. In addition, AR biomass and metabolite contents reached the maximum on day 42. The kinetic models for AR growth and triterpenoid and polysaccharide production were constructed, providing the basis for further optimization of culture conditions and large-scale culture.

Shoot Organogenesis and Regeneration from Leaf Seedlings of Diospyros oleifera Cheng

Persimmons (Diospyros) are economically important trees that are widely cultivated for wood production in China, and Diospyros oleifera Cheng is the main persimmon grafting stock. However, an efficient tissue culture system has not been perfected for D. oleifera due to the limits of proliferation and rooting cultures. Therefore, this study examined the effects of different plant growth regulators and concentrations on the primary culture of young embryos, induction of leaf callus, differentiation of adventitious shoots, and rooting culture of D. oleifera. The optimal formula for young embryo germination was 1/2 Murashige and Skoog (MS) medium containing 0.5 mg/L gibberellic acid (GA3); after 25 days, the sprouting rate of the young embryos was 67.3%. The best medium for leaf callus induction was 1/2MS medium containing 2.0 mg/L of 6-benzylaminopurine (6-BA) and 0.5 mg/L of naphthaleneacetic acid (NAA), and the callus induction rate was 88.9%. Then, the callus was transferred to 1/2MS medium containing 2.0 mg/L of zeatin (ZT), 0.5 mg/L of NAA, and 2.0 mg/L of thidiazuron (TDZ) to induce adventitious shoots; after 25 days, 5.4 buds were produced per explant, and the induction rate of the adventitious shoots was 88.3%. The adventitious shoots were transferred to 1/2MS medium containing 2.0 mg/L of ZT, 2.0 mg/L of 6-(γ,γ-dimethylallylamino)purine (2iP), and 0.1 mg/L of indole acetic acid (IAA) for the proliferation culture, for which the multiplication coefficient approached 7.5. After multiplication, the adventitious shoots were inoculated into 1/2MS medium containing 1.0 mg/L of indole butyric acid (IBA), 0.5 mg/L of NAA, and 1.0 mg/L of kinetin (KT); the rooting rate was 60.2%, and the average number of roots was 6.9.