Transcriptomic Analysis Reveals the Role of Silver Nanoparticles in Promoting Maize Germination

The germination, seedling growth, and crop productivity of maize seeds are significantly impacted by seed aging. This study investigated the efficacy of silver nanoparticles (AgNPs) as a seed priming agent for maize inbred lines exhibiting varying degrees of aging tolerance. Two inbred lines, aging-sensitive I178 and aging-tolerant X178, were used. AgNP treatment significantly promoted the germination of I178 (from 55% to 85%, compared with water treatment). Notable improvements were observed in root length, shoot length, and lateral root formation after AgNP treatment in I178. However, X178 showed no significant changes in germination and seedling growth after the AgNP treatment. Further transcriptomic analysis was performed on X178 and I178 before (water treatment) and after AgNP treatment to study genes and the expression network of the mechanism induced by AgNP promotion. In I178, AgNP treatment led to a substantial increase in differentially expressed genes (DEGs). A total of 800 DEGs were identified, with 517 being upregulated and 283 downregulated. The DEGs in I178 were mainly involved in metabolic processes, stress responses, and membrane repair. For example, genes related to lipid metabolism and membrane integrity were upregulated, along with seven genes associated with antioxidant action and redox metabolism. This indicates that AgNPs might enhance membrane stability and stress tolerance in I178. In contrast, X178 had a limited transcriptomic response to AgNP treatment. Although 874 DEGs were detected, the number of genes related to key processes like those in I178 did not change significantly, which is in line with its inherent aging tolerance. Overall, these results suggest that AgNPs can effectively improve seed vigor and counteract the negative effects of seed aging, especially in aging-sensitive maize lines. The mechanism likely occurs through regulating gene expression related to stress response, metabolic repair, and membrane stability. This study provides new insights into the molecular basis of AgNP-mediated seed vigor enhancement, which has potential implications for improving seed quality in agricultural production.