Brassinosteroids participate in many physiological processes in plants;however,their regulatory roles on the activities of the enzymes involved in dark phase of photosynthesis remains elusive.In this study,detached leaves and protoplasts of maize seedlings were treated with epi-brassinolide(EBR)and brassinazole followed by the determination of the contents of chlorophyll(a+b)and soluble sugars,and the activity of dark reaction enzymes and the expression of the relevant genes.The results showed that chlorophyll(a+b)content increased by 7.4%under 0.1μM EBR treatment for 48 h;furthermore,chlorophyll(a+b)content increased by 34%in detached leaves that were continuously soaked in brassinazole.In addition,the transcription levels of glyceraldehyde3-phosphate dehydrogenase subunit A(GAPA),cytoplasmic FBPase(cyFBPase),ribulose-1,5-bisphosphate carboxylase small subunit(rbcS),phosphoenolpyruvate carboxylase(PEPC),fructose-1,6-bisphosphatase(FBPase),Rubisco activaseβsubunit(RCAβ),ribulose-l,5-bisphosphate carboxylase large subunit(rbcL),and glutathione reductase(GR)were 96.8%,48.4%,79.3%,41%,85.6%,133.3%,68.8%,and 119.8%higher,respectively,in 0.1μM EBR than in the control group.The activity of RCA and Rubisco and soluble sugar content increased by 53.4%,28.7%,and 35.4%under 0.1μM EBR.Brassinazole inhibits the expression of these genes.However,the transcription level,protein content,and activity of some dark-reaction enzymes cannot be increased at the same time under EBR treatment.These results indicate that the effect of EBR on dark-reaction is mainly in transcription level.
展开▼
