Swedish wheat in the changing climate : screening for stable spring wheat genotypes from 2017 and 2018 with focus on protein quality for bread-making

Abstract: In recent years, wheat production and protein quality in wheat have been affected by climatic changes in Sweden and in many other parts of the world. Protein quality of wheat, determining the bread-making quality of flour, is a parameter sensitive to climate fluctuations and its stability has not been studied so far. In order to have good and stable bread-making quality characteristics under varying climate, it is important to screen for climate resilient wheat varieties, which could later be used in breeding of climate stable wheat. Therefore, the aim of this thesis was to study the effects of temperature and precipitation on the wheat gluten protein characteristics and to screen for climate stable wheat genotypes. Thirty spring wheat genotypes were grown in contrasting climates in 2017 and 2018. The wheat gluten protein parameters were studied using size exclusion high-performance liquid chromatography (SE-HPLC). Grain structural morphology was evaluated by light microscopy (LM). The results showed that contrasting climate conditions significantly affected most of the gluten protein parameters (TOTE, TOTU, %LUPP, %UPP and %LUMP). Higher amounts of polymeric gluten proteins were found in plants grown during the hot-dry season of 2018 compared to the cold-wet growing season of 2017. Four genotypes, Happy, 19, 22 and 28, had a higher percentage (>40%) of total unextractable polymeric protein (%UPP), which differed less than 5% between years (2017 and 2018). These genotypes were considered as having a stable bread-making quality. Structural morphology analysis of the wheat grain indicated the presence of gluten protein and starch distribution, as well as a weak inner structure of the grain components which limited paraffin embedding of the grain. Consequently, the tested LM methodology requires further development and improvement. This study concludes that some of the genotypes (Happy, 19, 22 and 28) might have the potential to withstand heat and drought and still provide attractive bread-making characteristics. However, further tests (SE-HPLC analysis, rheomix and baking) of these genotypes need to be done, preferably during several years, in order to analyse their bread-making stability.