Nano-silver and forskolin regulate rice seed germination mediated by OsPIP2-1

As timely germination of seeds is crucial to crop yield and quality, the low germination percentage for direct seeding in rice and pre-harvest sprouting during late stage of maturity have extremely adverse effects on rice production. Herein, we found that nano-silver inhibited rice seed germination while forskolin promoted this process. Germination assay showed that 20 μM AgNPs and 0.5 μM forskolin could be the optimal concentrations regulating rice seed germination. At the molecular level, an aquaporin gene, OsPIP2-1 , was most highly expressed among those homologous genes during rice seed germination, and was decreased by AgNPs and increased by forskolin. Meanwhile, the activity of α-amylase and its genes expression were also inhibited by AgNPs and promoted by forskolin. Next, the germination percentage of OsPIP2-1 overexpressing seeds was significantly higher than that of wild-type, and that of OsPIP2-1 knockout seeds was dramatically reduced. Furthermore, compared with the wild type, α-amylase activity and the transcription of OsAmy3C and OsAmy3E were increased in OsPIP2-1 overexpressing seeds and decreased in OsPIP2-1 knockout seeds, indicating that OsPIP2-1 positively regulates α-amylase. Interestingly, seed germination, α-amylase activity and its genes expression in OsPIP2-1 overexpressed and knockdout lines could also be inhibited by nano-silver and promoted by forskolin. In conclusion, we propose that nano-silver and forskolin regulated seed germination by modulating the expression of OsPIP2-1 and thus α-amylase. Our results may bring new application of nano-silver and forskolin in rice cultivation. ### Competing Interest Statement The authors have declared no competing interest.