The Combination of Physiological and Transcriptomic Approaches Reveals New Insights into the Molecular Mechanisms of Leymus chinensis Growth Under Different Shading Intensities

<i>Leymus chinensis</i> is a grass species in the family Triticeae that is found in the Eurasian grassland region and is known for its outstanding ecological advantages and economic value. However, the increasing adoption of photovoltaic agriculture has modified the light environment for the grass, markedly inhibiting its photosynthesis, growth, and yield. This study used physiological and transcriptomic analyses to investigate the complex response mechanisms of two <i>L. chinensis</i> genotypes (Zhongke No. 3 [<i>Lc3</i>] and Zhongke No. 5 [<i>Lc5</i>]) under shading stress. Growth phenotype analysis revealed the superior growth performance of <i>Lc3</i> under shading stress, evidenced by enhanced plant height and photosynthetic parameters. Additionally, differentially expressed genes (DEGs) were predominantly enriched in starch and sucrose metabolism and glycolysis/gluconeogenesis pathways, which were the most consistently enriched in both <i>L. chinensis</i> genotypes. However, the flavonoid biosynthesis and galactose metabolism pathways were more enriched in <i>Lc3</i>. Weighted gene co-expression network analysis identified the <i>LcGolS2</i> gene, which encodes galactinol synthase, as a potential hub gene for resistance to shade stress in comparisons across different cultivars and shading treatments. The use of qRT-PCR analysis further validated the genes involved in these pathways, suggesting that they may play critical roles in regulating the growth and development of <i>L. chinensis</i> under shading conditions. These findings provide new insights into the molecular mechanisms underlying the growth and development of <i>L. chinensis</i> under different shading stress conditions.