Three-dimensional econstruction and autophagy process analysis reveal development pattern of articulated laticifers in Taraxacum kok-saghyz Rodin

Abstract

Natural rubber is an important industrial raw material and strategic resource, and the potential shortage of supply needs to be urgently solved. Taraxacum kok-saghyz Rodin (TKS) contains a significant amount of natural rubber in laticifers that is a secretory structure and its structure and development process are closely related to rubber production. Recently, the application of three-dimensional (3D) econstruction in plant promotes the understanding of relationship between internal structure and its function. However, 3D structural distribution and the developmental process of articulated laticifers in TKS has not been throughly studied. In this study, the three-dimensional pattern of TKS laticifers were obtained for the first time using micro-computed tomography imaging and found that the TKS laticifers interconnect into a network in each individual concentric layer. Notebly, the 3D analyses and paraffin section combined with histochemistry showed that the laticifer maturity from inside to outside of the root was positively correlated with natural rubber content. Furthermore, observations on the western blotting, immunofluorescence, and ultrastructure of laticifers indicated that autophagy is involved in the development of laticifers and the intensity of autophagy showed a trend from weak to strong and then weak from inside to outside of the root. Autophagosomes fused with lysosome structures to degrade most of the organelles and cytoplasmic compounds, which possibly provides precursor substances for the synthesis of rubber particles in TKS laticifers. In summary, these findings provided a theoretical basis for further exploring the mechanism of regulating the development of laticifers to increase the content of natural rubber.