The environmental effects of genetically modified crops are now a global concern. It is important to monitor the potential environmental impact of transgenic corn after commercial release. In rhizosphere soil, plant roots interact with soil enzymes and microfauna, which can be affected by the transgenes of genetically modified crops. To determine the long-term impact of transgenic plant cultivation, we conducted a field study for 3 consecutive years (2018–2020) and observed the enzyme activities and nematode populations in plots planted with transgenic maize BQ-2, non-transgenic wild-type maize (Qi319), and inbred line B73. We took soil samples from three cornfields at four different growth stages (V3, V9, R1, and R6 stages); determined soil dehydrogenase, urease, and sucrase activities; and collected and identified soil nematodes to the genus level. The results demonstrated seasonal variations in dehydrogenase, urease, and sucrase activities. However, there was a consistent trend of change. The generic composition and diversity indices of the soil nematodes did not significantly differ, although significant seasonal variation was found in the individual densities of the principal trophic groups and the diversity indices of the nematodes in all three cornfields. The results of the study suggest that a 3-year cultivation of transgenic corn had no significant effects on soil enzyme activity and the soil nematode community. This study provides a theoretical basis for the environmental impact monitoring of transgenic corn.

Seed storability is an important trait for improving grain quality and germplasm conservation, but little is known about the regulatory mechanisms and gene networks involved. MicroRNAs (miRNAs) are small non-coding RNAs regulating the translation and accumulation of their target mRNAs by means of sequence complementarity and have recently emerged as critical regulators of seed germination. Here, we used the germinating embryos of two maize inbred lines with significant differences in seed storability to identify the miRNAs and target genes involved. We identified a total of 218 previously known and 448 novel miRNAs by miRNA sequencing and degradome analysis, of which 27 known and 11 newly predicted miRNAs are differentially expressed in two maize inbred lines, as measured by Gene Ontology (GO) enrichment analysis. We then combined transcriptome sequencing and real-time quantitative polymerase chain reaction (RT-PCR) to screen and confirm six pairs of differentially expressed miRNAs associated with seed storability, along with their negative regulatory target genes. The enrichment analysis suggested that the miRNAs/target gene mediation of seed storability occurs via the ethylene activation signaling pathway, hormone synthesis and signal transduction, as well as plant organ morphogenesis. Our results should help elucidate the mechanisms through which miRNAs are involved in seed storability in maize.