Previous research suggests that the senescence and death of the replaceable bud in chestnut cultivar (cv.) ‘Tima Zhenzhu’ involves programmed cell death (PCD). However, the molecular network responsible for regulating replaceable bud PCD is poorly characterized. Here, we performed transcriptomic profiling of the chestnut cv. ‘Tima Zhenzhu’ replaceable bud before (S20), during (S25), and after PCD (S30) to ascertain the molecular mechanism underlying the PCD process. A total of 5,779, 9,867, and 2,674 differentially expressed genes (DEGs) were discovered upon comparison of S20 vs. S25, S20 vs. S30, and S25 vs. S30, respectively. Approximately 6,137 DEGs common to at least two comparisons were selected for GO and KEGG enrichment analyses to interrogate the main corresponding biological functions and pathways. GO analysis showed that these common DEGs could be divided into three functional categories, including 15 cellular components, 14 molecular functions, and 19 biological processes. KEGG analysis found that “plant hormone signal transduction” included 93 DEGs. Overall, 441 DEGs were identified as related to the process of PCD. Most of these were found to be genes associated with ethylene signaling, as well as initiation and execution of various PCD processes. A hypothetical model, consisting of three overlapping processes, is proposed for the replaceable bud PCD: First, ethylene signaling is activated during preparation for PCD, in order to regulate the activity of downstream targets. Next, during PCD initiation, the up-regulation of several TFs (including MYB, MADS-box, bHLH, and NAC TFs) induces an increase in cytochrome c expression and in the cytosolic Ca2+ content, activating the Ca2+-dependent signaling cascade. Finally, during PCD execution, the process of autophagy and the activity of proteases (i.e., cysteine proteinases RD21A-like, metacaspase-9-like, vacuolar-processing enzyme-like, and senescence-associated proteins for hydrolysis) work synergistically to clear the cell of cellular components. When this process is complete, the replaceable bud senesces and dies.

This paper studied the dynamic characteristics of the deployment process of the replaceable interface mast and the vibration generated at the end of the mast. The interface is discretized by the absolute nodal coordinate thin shell element with gradient reduction, and the three-dimensional motion of the reconfigurable rigid body module is described by the natural coordinate method. The dynamic equations of the interface and the reconfigurable module without external constraints are established by the principle of virtual work. Finally, the dynamic models of each part are assembled into the dynamic model of the mast system deployment process through the system constraint equation. According to the established dynamic model of the mast system deployment process, the dynamic behavior changes of the replaceable interface mast are analyzed. At the same time, the differences in the deployment behavior of the replaceable interface mast under different system configuration schemes, flexible interface geometric parameters, and different driving laws are studied and compared. It provides guidance for the scheme configuration of the mast system, the structural design of the interface, and the deployment motion planning of the mast. According to the physical prototype and the assembly of the mast system model, the deployment process of the replaceable interface mast is experimentally analyzed. It shows that the established dynamic model of the mast system can correctly analyze the dynamic characteristics of the deployment behavior of the replaceable interface mast, which provides a reference for the design and behavior analysis of the mast system.