Comparison of Morphological Characteristics and Determination of Different Patterns for Rubber Particles in Dandelion and Different Rubber Grass Varieties

Green and Efficient Extraction of Taraxacum kok-saghyz Natural Rubber and Its Structural Analysis

Natural rubber (NR) is in high demand due to its excellent elasticity and physical and mechanical properties, but production is limited and NR is in short supply. There is an urgent need to find new alternative rubber sources. Taraxacum kok-saghyz (TKS), as a green, renewable, widely planted and high content rubber producing plant, has shown broad application prospects. The extraction process is the key to developing efficient, green, and high-purity Taraxacum kok-saghyz Natural Rubber (TKNR) to replace NR in various applications. In this study, TKS roots were processed through repeated boiling to remove inulin, followed by alkaline treatment with potassium hydroxide (KOH) to isolate lignin and facilitate cell wall disruption. Subsequent enzymatic hydrolysis using pectinase and cellulase enabled the dissolution of root-structure carbohydrates, thereby obtained TKNR. Structural characterization of TKNR was conducted and compared with that of NR. The results showed that the combined alkaline and enzymatic extraction methodology effectively isolates TKNR from TKS roots. Structural analysis reveals that TKNR closely resembles NR, having comparable molecular weight and distribution, crystallinity, and crosslinking networks, with both polymers primarily consisting of cis-1,4-polyisoprene.

Natural rubber - Increasing diversity of an irreplaceable renewable resource

This paper discusses the importance of introducing domestic natural rubber production and presents the rediscovery of a rubber-producing species, Scorzonera tau-saghyz or "mountain gum", originally discovered in 1929 on the Karatau mountains in Kazakhstan. This plant could potentially also be cultivated in the U.S. In this exploratory work, roots (2-5 years old) were harvested on June 16, 2021 from wild strands in the Karatau mountains, Kumantas ridge, and Saraba, Kazakhstan, and processed at the Ohio State University. The rubber extraction method was based on an indigenous method in Kazakhstan to make natural chewing gum. Water extraction followed by purification yielded 16.2 wt% rubber from the dry roots, in comparison with 4-8 wt% from most rubber dandelion (Taraxacum kok-saghyz) plants, also a potential domestic rubber producing plant. High-resolution size exclusion chromatography was used to analyze rubber samples. The molecular weights and gel and oligomer contents were very similar to the rubber from Hevea brasiliensis, the current commercial source of natural rubber. More detailed investigations of this very interesting rubber-producing plant are in progress.

Microscopic and Transcriptomic Analysis of Pollination Processes in Self-Incompatible Taraxacum koksaghyz

The transition of the Russian dandelion Taraxacum koksaghyz (Asteraceae) to a profitable, alternative crop producing natural rubber and inulin requires the optimization of several agronomic traits, cultivation conditions and harvesting procedures to improve the yield. However, efficient breeding is hindered by the obligatory sexual outcrossing of this species. Several other asters have been investigated to determine the mechanism of self-incompatibility, but the underlying molecular basis remains unclear. We therefore investigated the self-pollination and cross-pollination of two compatible T. koksaghyz varieties (TkMS2 and TkMS3) by microscopy and transcriptomic analysis to shed light on the pollination process. Self-pollination showed typical sporophytic self-incompatibility characteristics, with the rare pollen swelling at the pollen tube apex. In contrast, cross-pollination was characterized by pollen germination and penetration of the stigma by the growing pollen tubes. RNA-Seq was used to profile gene expression in the floret tissue during self-pollination and cross-pollination, and the differentially expressed genes were identified. This revealed three candidates for the early regulation of pollination in T. koksaghyz, which can be used to examine self-incompatibility mechanisms in more detail and to facilitate breeding programs.