Balancing act: transcriptomic, morphological, and biochemical insights into wheat endosperm development associated with bread quality

Despite the importance of bread quality in the food chain, research has primarily focused on quantity rather than quality. Bread quality is a complex trait that is heavily influenced by the genome’s ploidy level, environmental conditions, physiological factors, and their interactions. The wheat endosperm is rich in proteins and starch, which significantly affect bread quality. Most studies related to bread quality have focused on the role of gluten proteins, while starch has been considered in fewer studies. This study aimed to identify the factors affecting bread quality by comparing various growth aspects of two grain cultivars with extreme quality, with an emphasis on starch. We provide a primary view about the bread quality based on the transcriptome, morphological, biochemical, and structural aspects of two bread wheat cultivars. The transcriptomes were compared during endosperm formation using RNA-Seq, morphological characteristics of grain and endosperm during growth were studied by light and scanning electron microscopes, differences in protein content were assessed, and starch content was evaluated based on ingredients, required temperature, and particle size. Results show that a reduced need for expending energy on synchronizing gene expression and its application for further development, decreased or disrupted ethylene signaling activity, increased activity of carbon-related pathways, pathways aimed at preventing the decline of photosynthesis efficiency, and the biosynthesis process in high-quality cultivars are critical factors for enhancing endosperm quality. We found that the protein export pathway played a significant role in achieving higher protein content and quality compared to protein synthesis pathways. We demonstrated that starch is crucial due to its characteristics (spherical shape of large A-granules, higher number of B-granules, increased crystallinity, granule distribution among protein strands, and the amount of water loss during ripening). CO2 leakage may contribute to reducing quality. The findings indicated that improving the quality of endosperm content required plant internal management in allocation of its resources at the transcriptomic level. Earlier entrance into the aging could cause lower protein content, more water loss, incomplete growth and less uniform distribution of granules. The existence of regular molecular mechanisms and lack of a need for continuous adjustment can be factors that improve the quality.