Shading in mother plant decreasing seed vigor in wheat

High seed vigor has the potential to alleviate the adverse effects of unfavorable environmental conditions. Nonetheless, the influence of inevitable global dimming on seed viability remains uncertain. To examine the effects of global shading on seed vigor, we analyzed seed size, seed chemistry, and associated gene expression in four varieties subjected to 60% shade during both the vegetative and reproductive growth periods. Over a four-year average, the thousand kernel weights decreased by 20.18% during the vegetative growth stage and by 3.87% during the reproductive growth stage. Shading during the reproductive stage resulted in a significant increase in average protein content by 17.00%, accompanied by alterations in the protein components gliadin and gluten, as well as their respective ratios. Additionally, a significant reduction in the expression of starch synthesis genes and starch content was observed. The expression of genes involved in abscisic acid (ABA) synthesis was upregulated, while the expression of ABA-metabolizing genes was downregulated, leading to an elevated ABA content. Conversely, both the expression and content of gibberellin (GA3)-related genes were diminished. Principal component analysis (PCA) indicated that the ABA/GA3 ratio exerted the most substantial influence on seed vigor, followed by gliadin content. Our results thus indicated that shading of the mother plant during seed development in wheat decreased subsequent germination by mediating the biosynthesis of ABA, GA3, protein and starch.