Rapeseed contains high levels of glucosinolates (GSLs), playing pivotal roles in defense against herbivores and pests. As their presence in rapeseed reduces the value of the meal for animal feeding, intensive efforts to reduce them produced low-seed GSL cultivars. However, there is no such variety suitable for the south part of Japan. Here, we tested the effects of cold oxygen plasma (oxygen CP) on seed germination and GSL and lipid content, in three rapeseed cultivars. According to the cultivars, oxygen CP slightly stimulated seed germination and modified the GSL levels; decreased GSL levels in Westar and Kizakinonatane but increased those in Nanashikibu. In contrast, it negligibly affected the lipid content and composition in the three cultivars. Thus, oxygen CP modulated seed GSL levels without affecting seed viability and lipid content. Future optimization of this technique may help optimize rapeseed GSL content without plant breeding.

Gene expression variations of plant leaf are investigated by irradiating seed and leaf with oxygen or air plasmas. Enhancement of leaf growth is induced by oxygen plasma irradiation on seeds, which is supported by increased gene expression for protein synthesis, oxidative-reduction reactions, and decreased gene expression concerning DNA methylation and histone modification. Suppression of leaf growth is observed by the oxygen plasma, which would be owing to increased gene expression concerning heat shock protein and redox reaction, and decreased expression of photosynthesis and glycoprotein. Moreover, gene expression variation due to air plasma irradiation is almost the same as that of oxygen plasma. Active oxygen species are major factors in both oxygen and air plasmas for the variation of gene expressions in plants.

Gene expression variations of plant leaf are investigated by irradiating seed and leaf with oxygen or air plasmas. Enhancement of leaf growth is induced by oxygen plasma irradiation on seeds, which is supported by increased gene expression for protein synthesis, oxidative-reduction reactions and decreased gene expression concerning DNA methylation and histone modification. Suppression of leaf growth is observed by the oxygen plasma, which would be owing to increased gene expression concerning heat shock protein and redox reaction, and decreased expression of photosynthesis and glycoprotein. Also, gene expression variation due to air plasma irradiation is almost same as that of oxygen plasma. Active oxygen species are major factors in both oxygen and air plasmas for the variation of gene expressions in plant.