Transcriptomic analysis of seed germination improvement ofAndrographis paniculataresponding to air plasma treatment

The plasma seed treatment is effective for promoting seed germination in many crops. However, the biological mechanism remains unclear. Therefore, mRNA sequencing was used to screen differentially expressed genes in the germination process ofAndrographis paniculataseeds treated with air plasma (power density = 8.99 J/cm(3)). Following plasma treatment, the germination percentages were significantly higher than those of the control, they were 3.5 +/- 0.6%vs. 0 at 28 hours after sowing (HAS) and 50.3 +/- 2.6%vs. 37.3 +/- 1.7% at 48 HAS. After unigenes were assembled and annotated, 125 differentially expressed genes (DEGs) were detected at 28 HAS, compared with nine DEGs at 48 HAS, but no DEGs were detected at 0 HAS, indicating that air plasma treatment mainly changed the gene expression ofA.paniculataseeds at 28 HAS. TheNCED5expression level of the treated group was less than one-fifth of the control, and the expressions of three ethylene response factors were significantly higher than the control at 28 HAS, indicating that lower abscisic acid levels play an important role and ethylene signal transduction also participates in radicle protrusion.ACO,NRT1andPRP3expressions were significantly higher than in the control at 48 HAS, suggesting that higher ethylene levels cause the endosperm cap to weaken and start to grow root hairs and lateral roots earlier. These findings reveal that plasma promotes seed germination mainly by regulating the expression of hormone-related genes. And the possible signal transduction of related hormones was discussed.