Tetraploidization Increases the Contents of Functional Metabolites in Cnidium officinale

Cnidium officinale is an important medicinal crop grown in Asia for its pharmacological properties. In this study, tetraploid breeding was conducted to increases the content of medicinal compound and tolerance to the environmental conditions using in vitro shoot culture of C. officinale. For this, we generated tetraploid C. officinale plants using oryzalin, a chromosome doubling agent, and compared the morphological traits, cytological characteristics, and heat stress-responsive gene expression levels between tetraploid and diploid genotypes. Chromosome doubling efficiency was the highest in plantlets treated with 4.0 mg∙L−1 oryzalin for 2 days. Compared with diploids, the plant height of tetraploids was reduced, while the petiole diameter was increased by approximately 39%. The dry matter of tetraploid leaves was significantly higher than that of diploid leaves. Compared with diploids, tetraploids showed higher chloroplast number and stomatal complex size but lower chlorophyll and carotenoid contents. The phenolic content of tetraploid plantlets was significantly higher than that of diploid plantlets. Contents of naringin as well as salicylic acid and gentisic acid, which are strong antioxidant compounds, were dramatically increased upon tetraploidization. Interestingly, liquid chromatography–mass spectrometry (LC–MS) analyses revealed increased levels of senkyunolide F and phthalide in tetraploid roots but not in tetraploid or diploid leaves.

Sourcing and Propagation of Pontechium maculatum for Horticulture and Species Restoration

Pontechium maculatum, a species of ornamental, apicultural, health and medicinal value, is threatened in some Central European countries including Poland. Its propagation using seeds or in vitro techniques is needed for multiple applications including conservation. Generative propagation efficacy of P. maculatum plants representing different genetic resources (received from botanical gardens in Germany and in Poland) propagated from seeds or in tissue culture was assessed. Moreover, an efficient technique of propagation of P. maculatum using in vitro shoot culture from seedlings was elaborated for the first time. The highest propagation efficacy was noted for German plants of seed origin. The ability of seeds to germinate was similar for all plants; however, seeds were in a state of dormancy, which was broken by GA3. After two years of storage, the seeds still retained the ability to germinate though seeds from propagated in vitro plants germinated more poorly than those from seed-originated plants. The ploidy assessment showed that some in vitro-origin plants had altered DNA content. The results indicate that efficacy of generative propagation of P. maculatum is resource dependent. Furthermore, results suggest that cultivation in vitro influenced some generative features of examined species, which makes this way of P. maculatum propagation a valuable source of genetic variation and a potential breeding tool.

Optimization of rhizogenesis for in vitro shoot culture of Pinus massoniana Lamb.

The rooting capacity of Pinusmassoniana is poor, especially for mature trees, and has prevented the development of clonal forestry for P.massoniana. In this study, we varied explant types, subculture times and exogenous hormones for plantlet regeneration and assessed shoots for rooting rate and root number for P.massoniana. Following five repetitive grafts, new shoots from grafts used as explant sources were rejuvenated as observed from juvenile shoot morphology and anatomy, leading to greatly enhanced plant regeneration in comparison to that of mature materials from 26-year-old P.massoniana trees. The rooting capacity of subcultured shoots increased with successive subcultures, reaching a peak at 20 subcultures with 35–40 days per subculture. However, rooting performance was significantly reduced after 30 subcultures. The addition of naphthaleneacetic acid (NAA) plus indoleacetic acid in the medium improved the root number, but the combination of exogenous NAA with paclobutrazol (PBZ) increased rooting rate and root number. We thus greatly improved the rooting capacity of mature P.massoniana trees by optimizing explant types (rejuvenated), subculture times (20 subcultures, 35–40 days per subculture) and addition of NAA + PBZ to the rooting medium. The conditions can be used for efficient plantlet regeneration of P.massoniana.

Antioxidants and Phenolic Secretion in Sugarcane Genotypes Shoots Culture

Secretion of phenolic compounds is a major limitation for sugarcane in vitro shoot culture, causing a loss of regenerative capacity and subsequent cell death. In this study, micropropagation and phenolic secretion of four Saccharum genotypes were evaluated in presence of different antioxidants. Aseptic cultures of S. officinarum (PI 184794 and PI 88652), S. sinense (PI 29109) and S. robustum (UNK R65P35) were propagated on medium containing antioxidants, citric acid (100 mg/L), L-cysteine (100 mg/L), polyvynylpirrolidone (300 mg/L) and L-glutathione (50 mg/L) in two consecutive subculture cycles. Interaction between genotypes and antioxidants was significant in both cycles. All genotypes showed good shoot formation, shoot vigor and color, except in PI 88652 which had less shoot development in both the presence and absence of the antioxidants tested. PI 184794 displayed the highest shoot proliferation in the presence of citric acid, and UNK R65P35 produced more shoots per explant in the 2nd subculture. For S. sinense (PI 29109), in both subcultures, most shoots were observed in the presence of polyvynylpirrolidone. Medium discoloration due to phenolic secretion was reduced in the presence of citric acid and polyvynylpirrolidone. The type of secreted phenolic compounds differed with genotype as the Principal Component Analysis of cultivation media separated PI 88652 from PI 29109 and UKN R65P35. Phenolic compounds varied in composition and were secreted at various levels as a function of genotype and antioxidant type. Loadings plots indicated the genotype and antioxidant separations were broadly driven by flavonoid compounds.

Micropropagation of Weigela florida ‘Tango’ through In Vitro Shoot Culture

Weigela florida (Bunge) A. DC. is a popular flowering shrub adapted to a wide range of environmental conditions. Efficient methods for micropropagation of this species have not been well developed. The present study established a protocol for in vitro shoot culture of W. florida ‘Tango’ after a systematic evaluation of different culture media, cytokinins, and auxins on axillary shoot induction. Single-node stems were cultured on Driver and Kuniyuki Walnut (DKW) medium for initial production of axillary shoots. The shoots were used as explants and cultured on DKW medium supplemented with 8.88 μm 6-benzylaminopurine (BA) and 0.27 μm naphthaleneacetic acid (NAA), resulting in the production of more than six axillary shoots per explant. The axillary shoots could either be used as explants for additional shoot production or be cultured on ½ DKW medium supplemented with 0.25 μm indole-3-butyric acid (IBA) for rooting. Plantlets were transplanted into a substrate with 99% survival rate in a shaded greenhouse. This established method could be used for rapid propagation of W. florida to speed the introduction of new hybrids or cultivars for commercial production.