Institut für die Sicherheit biotechnologischer Verfahren bei Pflanzen
Natural rubber is a highly elastic polymer and an indispensable industrial material in numerous everyday products. In 2021, the global market for natural rubber was worth around 25 billion US dollars; depending on price levels, it is currently (2023/2024) roughly in the range of 25–30 billion US dollars. Tyres are the main area of application: around 70% of natural rubber continues to be used in the tyre industry, with the rest going into various technical rubber and latex products (including household, automotive and medical technology). Global consumption was around 14.7 million tonnes in 2022 and rose to around 15–15.4 million tonnes in 2023; further moderate growth to around 15.5–16 million tonnes is expected for 2024.Temporary imbalances between supply and demand are cyclical and nothing new; currently, they are caused by leaf fall diseases, weather effects, labour shortages and economic constraints in the smallholder sector. Synthetic, petroleum-based rubber partially replaces natural rubber in many applications, but does not achieve its unique properties (e.g. tear and fatigue resistance through strain crystallisation) in particularly demanding tyre applications.The most important source of natural rubber is Hevea brasiliensis. Typical yields are around 500–1,500 kg of dry rubber per hectare per year (higher yields are possible with intensive cultivation). Hevea thrives in a warm, humid climate belt close to the equator. The global planted area is estimated at around 14 million hectares; land expansion is taking place mainly in Southeast Asia and parts of China and poses risks to species-rich tropical forests. Since 2000, approximately 3 million hectares of tropical forest have been cleared for the cultivation of rubber tree plantations. Accordingly, there is growing pressure for deforestation-free procurement and traceability (including through new due diligence requirements in import markets). Against this backdrop, intensive research is being conducted into sustainable alternatives to Hevea. The international focus is on guayule (Parthenium argentatum) and Russian dandelion (Taraxacum koksaghyz, Tks). Both provide natural rubber with comparable physicochemical properties. Guayule rubber has made significant progress in recent years and has already been tested in tyre demonstrator applications, although according to our findings to date, the extracted guayule rubber does not meet the quality standards of the tyre industry. Tks is also suitable and shows advantages in temperate climates. Key breeding tasks accompanied by excellent research based on globally recognised expertise continue to be the focus of the public funding requested within the framework of the TAKOWIND projects. To date, the rubber content within Tks has been significantly increased; however, the yield per unit area remains limited due to the limited root biomass. Therefore, the focus has been placed on breeding material and method development, in particular on the systematic characterisation of interspecific hybrids, which have the potential for significantly higher root and thus rubber yields compared to pure Tks. Thus, increasing the rubber content in interspecific hybrids through the consistent application of established testing methods such as flow cytometry, PCR methods, next-generation sequencing approaches and rubber measurements before and after in vitro cloning appears to be readily feasible. Similarly, initial results show that root weights 5-10 times greater than normal are achieved in species hybrids of various ploidy levels.However, challenges in species hybridisation also became apparent, which, alongside the expansion of methods, are to be the central issues of the TAKOWIND V project. The main topics are: comparison of breeding methods with regard to variety development; characterisation of stand density as a factor influencing root mass and laticifer content in the root; flowering synchronisation/fertility enhancement in crosses of species hybrids; control of apomixis in breeding material and the production of double haploid species hybrids. With TAKOWIND V and the further promotion of interdisciplinary cooperation in research and the expansion of breeding activities, the path to economic viability is being consistently pursued.In breeding, TAKOWIND V focuses on increasing the rubber yield in hybrids and comparing different breeding methods in terms of variety development. Through the analysis of various molecular mechanisms of the cross between T. koksaghyz and T. officinale in TAKOWIND IV (recombination and epigenetic regulation) and the further development and application of species-specific markers, new crosses and progeny will be established and characterised in TAKOWIND V in a targeted manner. This will be accompanied by a series of research approaches and the development of further breeding methods for the effective production and characterisation of species hybrids (fertility barriers, tracking of apomixis genes, genomic prediction). ScreenSYS successfully produced the first double haploid T. koksaghyz plants in TAKOWIND IV, which represent a boost for both scientific research and breeding. ScreenSYS will optimise the established protocol in TAKOWIND V for further T. koksaghyz breeding lines and transfer it to species hybrids.JKI-SB will focus on the phenotyping of yield-relevant traits of species hybrids in relation to agronomic parameters. The influencing factors of plant density, root mass, genotype, latex distribution in the root and rubber content will be examined for their interdependence and recommendations for cultivation will be derived from this. Another focus is on the collection and characterisation of origins for the production of new species hybrids.
Federal Ministry of Agriculture, Food and Regional Identity
