iTRAQ and RNA-seq analyses provide an insight into mechanisms of recalcitrance in a medicinal plant Panax notoginseng seeds during the after-ripening process.

Panax notoginseng (Burk) F.H. Chen is an important economic and medicinal plant from the family of Araliaceae, and its seed is characterised by the recalcitrance and after-ripening process. However, the molecular mechanism on the dehydration sensitivity is not clear in recalcitrant seeds. In the present study, isobaric tag for relative and absolute quantification (iTRAQ) and RNA-seq were used to analyse the proteomic and transcriptomic changes in seeds of P. notoginseng in days after-ripening (DAR). A total of 454 differentially expressed proteins (DEPs) and 12 000 differentially expressed genes (DEGs) were obtained. The activity of enzymes related to antioxidant system were significantly increased, and the late embryogenesis abundant (LEA) protein family and most members of glutathione metabolism enzymes have been downregulated during the after-ripening process. The lack or inadequate accumulation of LEA proteins in the embryo and the low activity of antioxidant defense in glutathione metabolism might be the key factors leading to the dehydration sensitivity in recalcitrant seeds of P. notoginseng. In addition, the increased activity of elycolysis (EMP), citric acid cycle (TCA) and pentose phosphate pathway (PPP) pathways might be one of important signals to complete the after-ripening process. Overall, our study might provide a new insight into the molecular mechanism on dehydration sensitivity of recalcitrant seeds. The recalcitrant seeds in a medicinal plant Panax notoginseng (Burk) F.H. Chen are characterised by the dehydration sensitivity. Using iTRAQ-based proteomic and RNA-seq analysis, we find that the dehydration sensitivity of P. notoginseng seeds is gradually decreased, the lack of late embryogenesis abundant (LEA) proteins or inadequate accumulation in the embryo and the low activity of glutathione metabolism might be the key factors leading to the dehydration sensitivity of recalcitrant P. notoginseng seeds. The increased activity of energy metabolite is one of important signals for recalcitrant seeds to accomplish the after-ripening process. [ABSTRACT FROM AUTHOR]