Treatment of common Sunfower (Helianthus annus L.) seeds with radio-frequency electromagnetic field and cold plasma induces changes in seed phytohormone balance, seedling development and leaf protein expression

Abstract

Treatment of plant seeds with electromagnetic felds or non-thermal plasmas aims to take advantage of plant functional plasticity towards stimulation of plant agricultural performance. In this study, the efects of pre-sowing seed treatment using 200Pa vacuum (7min), 5.28MHz radio-frequency cold plasma (CP −2, 5, and 7min) and electromagnetic feld (EMF −5, 10, 15min) on seed germination kinetics, content of phytohormones, morphometric parameters of seedlings and leaf proteome were assessed. CP 7min and EMF 15min treatments caused 19–24% faster germination in vitro; germination in the substrate was accelerated by vacuum (9%) and EMF 15min (17%). The stressors did not change the seed germination percentage, with exception of EMF 5min treatment that caused a decrease by 7.5%. Meanwhile both CP 7min and EMF 15min treatments stimulated germination, but the EMF treatment resulted in higher weight of leaves. Stressor-specifc changes in phytohormone balance were detected in seeds: vacuum treatment decreased zeatin amount by 39%; CP treatments substantially increased gibberellin content, but other efects strongly varied with the treatment duration; the abscisic acid content was reduced by 55–60% after the EMF treatment. Analysis of the proteome showed that short exposure of seeds to the EMF or CP induced a similar long-term efect on gene expression in leaves, mostly stimulating expression of proteins involved in photosynthetic processes and their regulation.