Adaptive strategies to drought stress in grasses of the poaceae family under climate change: Physiological, genetic and molecular perspectives: A review.

Drought stress is one of the most critical abiotic factors which negatively impacts on growth, productivity, and survival of plants. Grass species have an important role in the sustainable intensification of cropping systems. This review focus on the specific drought tolerance characteristics in grass species and application of prevalent classical and molecular methods for genetic improvement of them to drought stress. Generally, grass species adapt to drought stress by utilizing more than one strategy including of changes in the root growth, photosynthetic pigments, activation of antioxidant enzymes, and accumulation of compatible osmolytes. They also have other specific characteristics consisted of summer dormancy, drought recovery, and persistence, which lead to drought adaptation after prolonged drought. Studies on different grasses, indicated that most of above mentioned traits usually have positive correlation with drought tolerance. Also, high heritability has been reported for most of them in different grasses. Therefore, an effective index might be considering in identification of drought tolerance genotypes. Recently, high-throughput imaging phenotyping and advanced molecular techniques such as genotyping-by-sequencing (GBS), RNA sequencing, genome-wide association study, and genome editing help conventional breeding methods to increase the accuracy, selection efficiency, genetic gains, and speed of breeding programs for developing drought tolerant cultivars.

Italian Ryegrass as a Forage Crop for the Baltics: Opportunities and Challenges in Light of Climate Change.

Grasslands are important for sustainable milk and meat production as well as for providing other ecosystem services. One of the most productive components of short-term grasslands is Italian ryegrass (Lolium multiflorum subsp. italicum Lam.), offering high yield, excellent feed value, and high palatability to animals but low tolerance to abiotic stress. Global climate warming opens new opportunities and could be beneficial in increasing the potential of biomass production. In this study, we aimed to assess an Italian ryegrass cultivar of Lithuanian origin, 'Ugne', for productivity and yield stability, with special emphasis on their relationship with climatic factors over a period of 14 years. The average winter temperatures and total spring precipitation explained 51% of the first-cut dry matter yield (DMY) variance. Second- and third-cut DMYs were associated with average temperature only. Italian ryegrass cv. 'Ugne' demonstrated the potential to produce high dry matter yields after warm winters and withstand summer drought spells under Lithuanian conditions. However, mid-to-late-summer heat waves might reduce productivity and should be taken into consideration when breeding new Italian ryegrass cultivars.

The Composition of Fatty Acids in Bee Pollen, Royal Jelly, Buckthorn Oil and Their Mixtures with Pollen Preserved for Storage.

Honey produced by A. mellifera contains minor components present in the nectar collected from plants. Various studies of honey components and all other bee products can be informative in assessing their quality. The aim of the present study was to determine the content and composition of fatty acids (FAs) in sea buckthorn oil (SBO), royal jelly (RJ) and bee pollen (BP) and the changes in FAs content in these products during storage. The diversity of FAs and the effect of storage time on FAs content was also evaluated for the prepared-for-preservation mixtures, which included the following samples: pollen mixed with honey at a ratio of 1:2 (w/w); sample BPH, a well; BPH + 1% (w/w) SBO; and BPH + 1% (w/w) SBO + 2% (w/w) RJ. Fresh bee-collected pollen and RJ were stored at -20 °C, whereas the conserved samples were stored at +4 °C in hermetically sealed jars. The data revealed that RJ demonstrated the highest diversity of fatty acids compared to BP and BP prepared for storage with honey along with SBO and RJ. Palmitic and stearic acids were found in the highest amounts out of the eight saturated fatty acids identified in the studied SBO and RJ. The amount of these fatty acids in RJ compared to SBO was 1.27 and 6.14 times higher, respectively. In total, twenty-two unsaturated fatty acids (USFA) were identified in RJ and fourteen were found in SBO. The SBO used in this study was found to be high in linoleic acid, resulting in an increased n-6 fatty acids ratio in the prepared samples. Essential fatty acids eicosapentaenoic (EPA) and docosahexaenoic (DHA) were found in RJ, as well as in BP and BP mixed with honey. These FAs were not identified in the samples prepared with SBO even in the sample supplemented with RJ. The highest decrease in docosadienoic fatty acid was found in the BPH sample compared to BP, while arachidonic acid mostly decreased in BPH + 1% SBO compared to the BPH + 1% (w/w) SBO + 2% (w/w) RJ samples stored at +4 °C. Bee-collected pollen had the greatest influence on the number of FAs in its mixture with honey.

Improving abiotic stress tolerance of forage grasses - prospects of using genome editing.

Due to an increase in the consumption of food, feed, and fuel and to meet global food security needs for the rapidly growing human population, there is a necessity to obtain high-yielding crops that can adapt to future climate changes. Currently, the main feed source used for ruminant livestock production is forage grasses. In temperate climate zones, perennial grasses grown for feed are widely distributed and tend to suffer under unfavorable environmental conditions. Genome editing has been shown to be an effective tool for the development of abiotic stress-resistant plants. The highly versatile CRISPR-Cas system enables increasingly complex modifications in genomes while maintaining precision and low off-target frequency mutations. In this review, we provide an overview of forage grass species that have been subjected to genome editing. We offer a perspective view on the generation of plants resilient to abiotic stresses. Due to the broad factors contributing to these stresses the review focuses on drought, salt, heat, and cold stresses. The application of new genomic techniques (e.g., CRISPR-Cas) allows addressing several challenges caused by climate change and abiotic stresses for developing forage grass cultivars with improved adaptation to the future climatic conditions. Genome editing will contribute towards developing safe and sustainable food systems.

Grain Yield Performance and Quality Characteristics of Waxy and Non-Waxy Winter Wheat Cultivars under High and Low-Input Farming Systems.

Waxy starch with a modified amylose-to-amylopectin ratio is desired for a range of applications in food and non-food industries; however, yield performance and grain quality characteristics of waxy wheat cultivars are usually inferior in comparison to advanced non-waxy cultivars. In this study, we compared waxy ('Eldija', 'Sarta') and non-waxy ('Skagen', 'Suleva DS') winter wheat cultivars grown under high and low-input farming systems over two cropping seasons by evaluating their yield and grain quality, including flour, dough, and starch physicochemical properties. The yield of waxy cv. 'Sarta' was significantly lower compared to the non-waxy cultivars across all trials; however, waxy cv. 'Eldija' had a similar yield as non-waxy cultivars (except under high-input conditions cv. 'Skagen'). Moreover, no significant differences were observed between protein and gluten content of waxy and non-waxy cultivars. Low amylose content typical for waxy wheat cultivars highly correlated (r ≥ 0.8) with lower falling number, flour yield and sedimentation values, lower nitrogen % used for grain, higher flour water absorption and flour particle size index. In general, properties dependent on starch structure demonstrated consistent and significant differences between both starch types. The prevailing heat waves during the grain filling period decreased grain test weight but increased protein and gluten content and caused gluten to be weaker. Dough development time at these conditions became longer, dough softening lowered and starch content decreased, but A-starch, starch peak and final viscosity values increased. Low-input farming had a negative effect on grain yield, grain nitrogen uptake and grain test weight but increased phosphorus content in grain. The unique dough mixing properties of waxy cultivar 'Eldija' suggest that it could be used in mixtures along with non-waxy wheat for dough quality improvement.

Genome-Wide Association Study to Identify Candidate Loci for Biomass Formation Under Water Deficit in Perennial Ryegrass.

Global warming is predicted to impact many agricultural areas, which will suffer from reduced water availability. Due to precipitation changes, mild summer droughts are expected to become more frequent, even in temperate regions. For perennial ryegrass (Lolium perenne L.), an important forage grass of the Poaceae family, leaf growth is a crucial factor determining biomass accumulation and hence forage yield. Although leaf elongation has been shown to be temperature-dependent under normal conditions, the genetic regulation of leaf growth under water deficit in perennial ryegrass is poorly understood. Herein, we evaluated the response to water deprivation in a diverse panel of perennial ryegrass genotypes, employing a high-precision phenotyping platform. The study revealed phenotypic variation for growth-related traits and significant (P < 0.05) differences in leaf growth under normal conditions within the subgroups of turf and forage type cultivars. The phenotypic data was combined with genotypic variants identified using genotyping-by-sequencing to conduct a genome-wide association study (GWAS). Using GWAS, we identified DNA polymorphisms significantly associated with leaf growth reduction under water deprivation. These polymorphisms were adjacent to genes predicted to encode for phytochrome B and a MYB41 transcription factor. The result obtained in the present study will increase our understanding on the complex molecular mechanisms involved in plant growth under water deficit. Moreover, the single nucleotide polymorphism (SNP) markers identified will serve as a valuable resource in future breeding programs to select for enhanced biomass formation under mild summer drought conditions.

Phenotyping a Dynamic Trait: Leaf Growth of Perennial Ryegrass Under Water Limiting Conditions.

Water limitation is one of the major factors reducing crop productivity worldwide. In order to develop efficient breeding strategies to improve drought tolerance, accurate methods to identify when a plant reduces growth as a consequence of water deficit have yet to be established. In perennial ryegrass (Lolium perenne L.), an important forage grass of the Poaceae family, leaf elongation is a key factor determining plant growth and hence forage yield. Although leaf elongation has been shown to be temperature-dependent under non-stress conditions, the impact of water limitation on leaf elongation in perennial ryegrass is poorly understood. We describe a method for quantifying tolerance to water deficit based on leaf elongation in relation to temperature and soil moisture in perennial ryegrass. With decreasing soil moisture, three growth response phases were identified: first, a "normal" phase where growth is mainly determined by temperature, second a "slow" phase where leaf elongation decreases proportionally to soil water potential and third an "arrest" phase where leaf growth terminates. A custom R function was able to quantify the points which demarcate these phases and can be used to describe the response of plants to water deficit. Applied to different perennial ryegrass genotypes, this function revealed significant genotypic variation in the response of leaf growth to temperature and soil moisture. Dynamic phenotyping of leaf elongation can be used as a tool to accurately quantify tolerance to water deficit in perennial ryegrass and to improve this trait by breeding. Moreover, the tools presented here are applicable to study the plant response to other stresses in species with linear, graminoid leaf morphology.