Wheat quality under a climate spell : a focus on protein, physico-chemical and growth characteristics evaluated by innovatively combined approaches

The quality of bread is largely determined by the gluten protein concentration and composition, both greatly influenced by environmental factors such as heat and drought. Future climate in Sweden is expected to fluctuate severely, affecting gluten proteins and the production of bread wheat, as well as future availability of food. The thesis aimed to enhance knowledge of the effect of varying climates on the glutenprotein quality in Swedish wheat and to evaluate new methods for yield and gluten protein screening in order to assist in future wheat breeding programs. In this thesis, plant growth-yield traits and gluten protein quality in flour and dough were studied in Swedish wheat of varying genetic backgrounds and imported varieties, all grown in diverse environments in Sweden.Red-green-blue (RGB) imaging and analytical chromatography tools, such as size exclusion high performance liquid chromatography (SE-HPLC) and mass spectrometry (LC-MS/MS), as well as near infrared spectroscopy (NIR) were used to study wheat plants and flour materials. A mixograph was used to prepare dough in this study. Robust flour sedimentation methods, such as swelling index of glutenins (SIG) and solvent retention capacity (SRC), were used to examine the gluten protein characteristics of wheat flour from varying growing environments and were compared to industrial flour screening methods.The results show that the combined heat-drought stresses negatively affected biomass, yield and thousand-kernel weight (TKW) in the wheat studied. During extreme heat and prolonged drought, higher amounts of large polymeric gluten proteins (%UPP) were observed in the spring wheat flours in both field and controlledgrowth environments. Total extractable gluten protein (TOTE) was higher in the wheat genotypes grown in the cool climate in the field and combined heat-drought stress in the greenhouse. No difference in optimum dough mixing time in wheat from different years was observed. Dough mixing time, together with the gluten protein parameters (%UPP and TOTE) could be promising traits for gluten stability evaluation in varying climates. RGB imaging in combination with SE-HPLC can be useful in screening stable wheat genotypes for yield and gluten quality in varying climates. A combination of robust small-scale sedimentation tests to assess wheat flour suitability for bread-making, SIG in diluted lactic acid, SRC and SE-HPLC can be effectively used for efficient screening of wheat resilient to climate change. The new set of combined methods that include plant imaging, flour sedimentation, analytical chromatography and NIR, is of the greatest interest for both breeding and breadbaking industries to evaluate wheat in a changing climate

Design och hållbarhetsbedömning av tvågrödesystem med grödor till både bioenergi och livsmedel i södra Sverige

Due to short growing season harvesting two crops sequentially in one year is not common in Sweden. In this experiment a cropping system was designed where rye was grown as a first crop for production of biomass feedstock for bioenergy. Aim of the study was to design a cropping system that can increase overall crop production and provide food, feed, energy and non-market ecosystem services such as increase annual carbon input and reduce leaching loss of nitrogen in the soil. With these ideas a field experiment was conducted in 2014-15 in Dybäck, southern part of Sweden. Rye was planted as first crop in September 2014 and harvested in green condition for energy production at the end of May, 2015. Blue lupin, soybean, black bean, lentil and buckwheat were selected as second crops and were grown in between June to September, 2015. It was an interdisciplinary research work. Both quantitative and qualitative methods were used for this study. A literature search was conducted to collect preliminary data to assess sustainability of double cropping system using Sustainability Assessment of Food and Agriculture systems (SAFA) as a concept. Quantitative method was used for determining crop yield and crop residues. Qualitative method was used to investigate possible motives and constraints that might influence farmers’ decision to adopt double cropping system through semi-structured interviews. According to the literatures reviewed, conventional double cropping system requires a high level of water consumption and fertilizer utilization. This system also emits a high quantity of GHG. However, due to high soil coverage the system may enhance soil quality and protects soil from land degradation. Double cropping system also supports a large number of diverse species such as beetles and spiders. Increase yield could result in rise in net income. It should be noted that overall outcome of the double cropping system can greatly vary depending on the country/region, climate, soil, choice of the crops/varieties and, cultivation system (irrigated/non-irrigated, tillage/non- tillage, organic/conventional). Grain yield of lentil was highest (1.7 t/ha) among all the crops. Grain yield of buckwheat, black bean, soybean and blue lupin were 1.3 t/ha, 0.9 t/ha, 0.6 t/ha and 0.5 t/ha respectively. Production of crop residues was highest in buckwheat (3.2 t/ha). Crop residues production of lentil, black bean, soybean and blue lupin were 2.1 t/ha, 1.1 t/ha, 1.1 t/ha and 0.8 t/ha respectively. Highest annual C input in the soil was determined in buckwheat (304.2 kg/ha). Annual C input in the soil by lentil, blue lupin, black bean and soybean were 214.5 kg/ha, 121.7 kg/ha, 107.7 kg/ha and 101.2 kg/ha respectively. Amount of available N was determined for three crops: buckwheat, lentil and soybean at the depth of 0-60 cm. Total amount of available nitrogen in buckwheat, soybean and lentil were 14.3 kg/ha, 11.3 kg/ha and 9.6 kg/ha respectively. Crops residues are suitable for animal feed and energy production. Results from five interviews demonstrated that absence of market, lack of suitable machineries to handle second crops and lack of knowledge of double cropping system might be the major barriers of potential adoption of bioenergy double cropping system by the farmers who are growing rye for production of biomass feedstock for bioenergy production

Striving for Stability in the Dough Mixing Quality of Spring Wheat under the Influence of Prolonged Heat and Drought

The effects of prolonged heat and drought stress and cool growing conditions on dough mixing quality traits of spring wheat (Triticum aestivum L.) were studied in fifty-six genotypes grown in 2017 and 2018 in southern Sweden. The mixing parameters evaluated by mixograph and the gluten protein characteristics studied by size exclusion high-performance liquid chromatography (SE-HPLC) in dough were compared between the two growing seasons which were very different in length, temperature and precipitation. The genotypes varying in gluten strength between the growing seasons (<= 5%, <= 12%, and <= 17%) from three groups (stable (S), moderately stable (MS), and of varying stability (VS)) were studied. The results indicate that most of the mixing parameters were more strongly impacted by the interaction between the group, genotype, and year than by their individual contribution. The excessive prolonged heat and drought did not impact the buildup and mixing time expressed as peak time and time 1-2. The gluten polymeric proteins (unextractable, %UPP; total unextractable, TOTU) and large unextractable monomeric proteins (%LUMP) were closely associated with buildup and water absorption in dough. Major significant differences were found in the dough mixing parameters between the years within each group. In Groups S and MS, the majority of genotypes showed the smallest variation in the dough mixing parameters responsible for the gluten strength and dough development between the years. The mixing parameters such as time 1-2, buildup, and peak time (which were not affected by prolonged heat and drought stress) together with the selected gluten protein parameters (%UPP, TOTU, and %LUMP) are essential components to be used in future screening of dough mixing quality in wheat in severe growing environments

Neofunctionalization of mitochondrial proteins and incorporation into signaling networks in plants

Because of their symbiotic origin, many mitochondrial proteins are well conserved across eukaryotic kingdoms. It is however less obvious how specific lineages have obtained novel nuclear-encoded mitochondrial proteins. Here, we report a case of mitochondrial neofunctionalization in plants. Phylogenetic analysis of genes containing the Domain of Unknown Function 295 (DUF295) revealed that the domain likely originated in Angiosperms. The C-terminal DUF295 domain is usually accompanied by an N-terminal F-box domain, involved in ubiquitin ligation via binding with ASK1/SKP1-type proteins. Due to gene duplication, the gene family has expanded rapidly, with 94 DUF295-related genes in Arabidopsis thaliana alone. Two DUF295 family subgroups have uniquely evolved and quickly expanded within Brassicaceae. One of these subgroups has completely lost the F-box, but instead obtained strongly predicted mitochondrial targeting peptides. We show that several representatives of this DUF295 Organellar group are effectively targeted to plant mitochondria and chloroplasts. Furthermore, many DUF295 Organellar genes are induced by mitochondrial dysfunction, whereas F-Box DUF295 genes are not. In agreement, several Brassicaceae-specific DUF295 Organellar genes were incorporated in the evolutionary much older ANAC017-dependent mitochondrial retrograde signaling pathway. Finally, a representative set of DUF295 T-DNA insertion mutants was created. No obvious aberrant phenotypes during normal growth and mitochondrial dysfunction were observed, most likely due to the large extent of gene duplication and redundancy. Overall, this study provides insight into how novel mitochondrial proteins can be created via “intercompartmental” gene duplication events. Moreover, our analysis shows that these newly evolved genes can then be specifically integrated into relevant, pre-existing coexpression networks

An mTRAN-mRNA interaction mediates mitochondrial translation initiation in plants

Plant mitochondria represent the largest group of respiring organelles on the planet. Plant mitochondrial messenger RNAs (mRNAs) lack Shine-Dalgarno-like ribosome-binding sites, so it is unknown how plant mitoribosomes recognize mRNA. We show that “mitochondrial translation factors” mTRAN1 and mTRAN2 are land plant–specific proteins, required for normal mitochondrial respiration chain biogenesis. Our studies suggest that mTRANs are noncanonical pentatricopeptide repeat (PPR)–like RNA binding proteins of the mitoribosomal “small” subunit. We identified conserved Adenosine (A)/Uridine (U)-rich motifs in the 5′ regions of plant mitochondrial mRNAs. mTRAN1 binds this motif, suggesting that it is a mitoribosome homing factor to identify mRNAs. We demonstrate that mTRANs are likely required for translation of all plant mitochondrial mRNAs. Plant mitochondrial translation initiation thus appears to use a protein-mRNA interaction that is divergent from bacteria or mammalian mitochondria

Bread-making quality in a changing climate: In search of climate stable genotypes and robust screening methods for wheat

Wheat is one of the major crops in the world serving as an important source of nutrients for human consumption. Fluctuating climate with increasing heat, drought and precipitation, as well as rising concentration of CO2 has been found to significantly affect yield and quality of wheat worldwide. This introductory paper presents latest overview on the effect of fluctuating climate on wheat yield and gluten protein quality with emphasis on bread-making quality in Sweden and worldwide. Wheat gluten protein quality, as the main determinant of bread making quality, has been discussed in relation to the impact from the climate change. The concentration of gluten proteins and the gluten protein types are greatly affected by the varying climate and by the rate and timing of nitrogen fertilizer. Breeding for wheat quality stability is one of the main strategies to tackle climate induced variation in wheat quality and to ensure food security in the world. Therefore, the urgent need is to develop wheat varieties that are adapted to climate fluctuations and could deliver consistent yields and sufficient qualities of the wheat flour for bread and other products over different locations and years. In regard to this, still several challenges exist, and these include a need of efficient and accurate methods to evaluate wheat quality stability, which has been briefly discussed in this paper. Use of latest modern analytical and breeding tools such as, proteomics and a high throughput plant phenotyping (HTPP), as potential ways to improve the genotype selection efficiency in breeding process have been also discussed. In addition, crop performance prediction models based on simulation and gene mapping may improve the selection efficiency and speed up the breeding process to develop new climate resilient wheat varieties. Currently used methods for assessing wheat flour quality and its suitability for bread-making by wheat breeders and the millers are classical rheological tests evaluated by farinograph, alveograph, extensograph and empirical tests such as, sedimentation volume measurement and bread baking. A large number of these quality tests together with great amount of wheat grains (2–5 kg) are required, are the challenging factors requiring new robust and efficient methods for wheat flour and bread quality evaluation. Therefore, a need to develop small scale reliable tests for assessing flour quality for bread-making is of high relevance for wheat breeding and baking industry. Combination of different small scale wheat quality screening tests, modern breeding tools and crop performance prediction models is needed in order to improve selection efficiency in development of climate stable wheat varieties

Impacts of heat, drought, and combined heat-drought stress on yield, phenotypic traits, and gluten protein traits: capturing stability of spring wheat in excessive environments

Wheat production and end-use quality are severely threatened by drought and heat stresses. This study evaluated stress impacts on phenotypic and gluten protein characteristics of eight spring wheat genotypes (Diskett, Happy, Bumble, SW1, SW2, SW3, SW4, and SW5) grown to maturity under controlled conditions (Biotron) using RGB imaging and size-exclusion high-performance liquid chromatography (SE-HPLC). Among the stress treatments compared, combined heat-drought stress had the most severe negative impacts on biomass (real and digital), grain yield, and thousand kernel weight. Conversely, it had a positive effect on most gluten parameters evaluated by SE-HPLC and resulted in a positive correlation between spike traits and gluten strength, expressed as unextractable gluten polymer (%UPP) and large monomeric protein (%LUMP). The best performing genotypes in terms of stability were Happy, Diskett, SW1, and SW2, which should be further explored as attractive breeding material for developing climate-resistant genotypes with improved bread-making quality. RGB imaging in combination with gluten protein screening by SE-HPLC could thus be a valuable approach for identifying climate stress-tolerant wheat genotypes

Striving for Stability in the Dough Mixing Quality of Spring Wheat under the Influence of Prolonged Heat and Drought

The effects of prolonged heat and drought stress and cool growing conditions on dough mixing quality traits of spring wheat (Triticum aestivum L.) were studied in fifty-six genotypes grown in 2017 and 2018 in southern Sweden. The mixing parameters evaluated by mixograph and the gluten protein characteristics studied by size exclusion high-performance liquid chromatography (SE-HPLC) in dough were compared between the two growing seasons which were very different in length, temperature and precipitation. The genotypes varying in gluten strength between the growing seasons (&le;5%, &le;12%, and &le;17%) from three groups (stable (S), moderately stable (MS), and of varying stability (VS)) were studied. The results indicate that most of the mixing parameters were more strongly impacted by the interaction between the group, genotype, and year than by their individual contribution. The excessive prolonged heat and drought did not impact the buildup and mixing time expressed as peak time and time 1&ndash;2. The gluten polymeric proteins (unextractable, %UPP; total unextractable, TOTU) and large unextractable monomeric proteins (%LUMP) were closely associated with buildup and water absorption in dough. Major significant differences were found in the dough mixing parameters between the years within each group. In Groups S and MS, the majority of genotypes showed the smallest variation in the dough mixing parameters responsible for the gluten strength and dough development between the years. The mixing parameters such as time 1&ndash;2, buildup, and peak time (which were not affected by prolonged heat and drought stress) together with the selected gluten protein parameters (%UPP, TOTU, and %LUMP) are essential components to be used in future screening of dough mixing quality in wheat in severe growing environments

Impacts of heat, drought, and combined heat–drought stress on yield, phenotypic traits, and gluten protein traits: capturing stability of spring wheat in excessive environments

Wheat production and end-use quality are severely threatened by drought and heat stresses. This study evaluated stress impacts on phenotypic and gluten protein characteristics of eight spring wheat genotypes (Diskett, Happy, Bumble, SW1, SW2, SW3, SW4, and SW5) grown to maturity under controlled conditions (Biotron) using RGB imaging and size-exclusion high-performance liquid chromatography (SE-HPLC). Among the stress treatments compared, combined heat–drought stress had the most severe negative impacts on biomass (real and digital), grain yield, and thousand kernel weight. Conversely, it had a positive effect on most gluten parameters evaluated by SE-HPLC and resulted in a positive correlation between spike traits and gluten strength, expressed as unextractable gluten polymer (%UPP) and large monomeric protein (%LUMP). The best performing genotypes in terms of stability were Happy, Diskett, SW1, and SW2, which should be further explored as attractive breeding material for developing climate-resistant genotypes with improved bread-making quality. RGB imaging in combination with gluten protein screening by SE-HPLC could thus be a valuable approach for identifying climate stress–tolerant wheat genotypes

Prolonged heat and drought versus cool climate on the Swedish spring wheat breeding lines : Impact on the gluten protein quality and grain microstructure

Fluctuating climate, heat, and drought are expected to considerably impact bread wheat (Triticum aestivum) quality in the coming years and, as wheat is an essential food element worldwide, this will have significant implications for future food security and the global economy. This leads to an urgent need for developing wheat varieties with stable yield and gluten quality. In this study, we investigated the effect of heat and drought, compared to a cool climate, on gluten proteins in 294 spring wheat genotypes grown in 2017 and 2018 in Sweden. Gluten protein parameters were studied by size exclusion high-performance liquid chromatography (SE-HPLC) and grain morphology by X-ray tomography. The prolonged heat and drought led to: (i) increased gluten polymerization and the formation of large polymers, as defined by the percentage of unextractable polymers in total polymers (%UPP) and the percentage of large unextractable polymers in total large polymers (%LUPP); and (ii) increase in large monomers, as defined by the percentage of large unextractable monomers in the total large monomers (%LUMP) and the ratio of monomers versus polymers (Mon/Pol) in the flour. The cooler climate also led to an increase in total protein concentration and accumulation of the monomeric proteins and total SDS-extractable proteins (TOTE). No difference in the total amount of SDS-unextractable proteins (TOTU) was found between the studied climates. Due to the heat and drought stress, the grain yield decreased in most of the genotypes, while the grain microstructure varied only to a minor extent. The wheat genotypes identified in the study that provide good yields and stable gluten properties in both prolonged heat–drought and cool environments are strong candidates to contribute to a secure, self-sufficient future wheat supply in the face of an evolving climate in Sweden and in similar climates worldwide