Genome Editing in Crop Plant Research—Alignment of Expectations and Current Developments

The rapid development of genome editing and other new genomic techniques (NGT) has evoked manifold expectations on purposes of the application of these techniques to crop plants. In this study, we identify and align these expectations with current scientific development. We apply a semi-quantitative text analysis approach on political, economic, and scientific opinion papers to disentangle and extract expectations towards the application of NGT-based plants. Using the sustainable development goals (SDG) of the 2030 agenda as categories, we identify contributions to food security or adaptation to climatic changes as the most frequently mentioned expectations, accompanied by the notion of sustainable agriculture and food systems. We then link SDG with relevant plant traits and review existing research and commercial field trials for genome-edited crop plants. For a detailed analysis we pick as representative traits drought tolerance and resistance against fungal pathogens. Diverse genetic setscrews for both traits have been identified, modified, and tested under laboratory conditions, although there are only a few in the field. All in all, NGT-plants that can withstand more than one stressor or different environments are not documented in advanced development states. We further conclude that developing new plants with modified traits will not be sufficient to reach food security or adaption to climatic changes in a short time frame. Further scientific development of sustainable agricultural systems will need to play an important role to tackle SDG challenges, as well.

Characterization and potential utilization of recently available milk thistle, Silybum marianum (L.) Gaertn., wild type and mutant accessions

Milk thistle, Silybum marianum (L.) Gaertn. (Asteraceae), is an economically important medicinal plant utilized for silymarin production. Moreover, the species has been positively evaluated for vegetable oil and biomass production. Despite these positive characteristics, milk thistle is still marked by traits that are typical of undomesticated species (most importantly natural fruit dispersal at maturity) and requires further genetic improvement for its complete exploitation. This manuscript summarizes all the information collected through time about a collection of nine milk thistle wild and mutant lines and it discusses the possible further utilization of these genotypes. The accessions are characterized by interesting traits related to: fruit silymarin composition (S. marianum chemotype A and B), fruit fatty acid composition (high oleic and high stearic acid lines), fruit condensed tannins content, vegetative biomass composition (modification of xylans or lignin content), vegetative biomass structure (dwarf and tall lines), modifications of leaf variegation (hypervareigated line) and different types of fruit shatter resistance at maturity. All the lines underwent subsequent generations of selfing and are stable for all the described traits. The accessions will be made available at the Genebank of the Leibniz Institute of Plant Genetics and Crop Plant Research (IPK, Gatersleben) and may prove to be a useful genetic material for the improvement of qualitative fruit traits (silymarin quality, fatty acid composition) and for the further development of shatter-resistant S. marianum genotypes towards the complete domestication of this promising species.

Screening for Drought Tolerance in Maize (Zea mays L.) Germplasm Using Germination and Seedling Traits under Simulated Drought Conditions

Maize is known to be susceptible to drought stress, which negatively affects vegetative growth and biomass production, as well as the formation of reproductive organs and yield parameters. In this study, 27 responsive traits of germination (G) and seedlings growth were evaluated for 40 accessions of the Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) germplasm collection, under no stress and simulated drought stress treatments by 10%, 15%, and 20% of polyethylene glycol (PEG). The three treatments significantly reduced G% and retarded seedlings growth, particularly the 15% and 20% PEG treatments; these two treatments also resulted in a significant increase of abnormal seedlings (AS). The heritability (H2) and correlations of the traits were estimated, and drought tolerance indices (DTIs) were calculated for traits and accessions. The H2 of G% values were reduced, and H2 for AS% increased as the PEG stress increased. Positive correlations were found between most trait pairs, particularly shoot and root traits, with 48 highly significant correlations under no stress and 25 highly significant correlations under the 10% PEG treatments, particularly for shoot and root traits. The medium to high heritability of shoot and root seedling traits provides a sound basis for further genetic analyses. PCA analysis clearly grouped accessions with high DTIs together and the accessions with low DTIs together, indicating that the DTI indicates the stress tolerance level of maize germplasm. However, the resemblance in DTI values does not clearly reflect the origin or taxonomic assignments to subspecies and varieties of the examined accessions.

Interrelationships between Seed Yield and 16 Related Traits of 81 Garden Cress Landraces

This research uses path analysis to determine the interrelationships among seed yield and 16 related Morphological traits. Eighty-one garden cress accessions from IPK (Department of Leibniz Institute of Plant Genetics and Crop Plant Research) were grown in two growing seasons (2012–13) to determine the important components of seed yield. Observations were recorded on 20 other canola traits. Correlation coefficient analysis revealed that seed yield was positively correlated with all traits except plant height (PH) in the first year and except main axis length (MAL) and PH in the second year. Sequential path analysis (SPA) identified the thousand-seed weight (TSW), number of siliques per plant (NSP) and height of first silique (HFS) as important first order traits influenced seed yield in first year. Plant height, NSP, and the TSW were important first-order traits that influenced seed yield in the second year. This indicates that breeding programs should be based on these traits for further improvement of the garden cress. All direct effects were significant, as indicated by bootstrap analysis. The results suggest that TSW and NSP could be used as a selection criterion in selecting for increased seed yield in garden cress.

Predicting plant biomass accumulation from image-derived parameters

Image-based high-throughput phenotyping technologies have been rapidly developed in plant science recently and they provide a great potential to gain more valuable information than traditionally destructive methods. Predicting plant biomass is regarded as a key purpose for plant breeders and ecologist. However, it is a great challenge to find a suitable model to predict plant biomass in the context of high-throughput phenotyping. In the present study, we constructed several models to examine the quantitative relationship between image-based features and plant biomass accumulation. Our methodology has been applied to three consecutive barley experiments with control and stress treatments. The results proved that plant biomass can be accurately predicted from image-based parameters using a random forest model. The high prediction accuracy based on this model, in particular the cross-experiment performance, is promising to relieve the phenotyping bottleneck in biomass measurement in breeding applications. The relative contribution of individual features for predicting biomass was further quantified, revealing new insights into the phenotypic determinants of plant biomass outcome. What’s more, the methods could also be used to determine the most important image-based features related to plant biomass accumulation, which would be promising for subsequent genetic mapping to uncover the genetic basis of biomass.One-sentence SummaryWe demonstrated that plant biomass can be accurately predicted from image-based parameters in the context of high-throughput phenotyping.FootnotesThis work was supported by the Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), the Robert Bosch Stiftung (32.5.8003.0116.0) and the Federal Agency for Agriculture and Food (BEL, 15/12-13, 530-06.01-BiKo CHN) and the Federal Ministry of Education and Research (BMBF, 0315958A and 031A053B). This research was furthermore enabled with support of the European Plant Phenotyping Network (EPPN, grant agreement no. 284443) funded by the FP7 Research Infrastructures Programme of the European Union.

The Balkan collections 1941–1942 of Hans Stubbe in the Gatersleben Gene Bank

The German Federal Gene Bank at the Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) in Gatersleben comprises ca. 148 000 accessions of crop plants and their wild relatives. Among these, material from Albania and Greece is represented with ca. 1100 and more than 2700 accessions, respectively. IPK’s collection of Albanian germplasm is the world’s largest collection, while IPK’s Greek germplasm collection is the third largest holding of Greek crops and their wild relatives. The largest part of this material (ca. 200 and 1600 accessions from Albania and Greece, respectively) originates from two collecting expeditions carried out by Hans Stubbe, the founder of the Institute for Cultivated Plant Research, and other German collectors during the Second World War, in 1941 (ca. 700 accessions) and 1942 (ca. 1100 accessions). Stubbe’s expeditions are described with respect to the regions visited, species collected, plus a comparison between the original collections and their present state in the IPK Gene Bank is provided. A formal scientific report about the results of these expeditions had never been published before. The material from these expeditions can be freely requested from the IPK Gene Bank, after signing a Material Transfer Agreement.