Deciphering Molecular Mechanism of Intermediate Secondary Growth and Internode Elongation of Castor Bean (Ricinus communis L.) by combined analysis of transcriptome and metabolome
The length of internodes is critical in determining the height of the castor plant (Ricinus communis L.), and is closely associated with internode elongation. However, the exact mechanisms underlying internode elongation, particularly in the main stem of the castor plant, remain uncertain. To investigate further, we conducted a study using the dwarf castor variety 071113, comparing it with the homologous high-stalk Zhuansihao as a control. Our research included cytological observation, physiological measurement, transcriptome sequencing, and metabolic determination. By integrating these findings, we discovered that the dwarf 071113 undergoes earlier main stem lignification development and has a more active lignin synthesis pathway in internode intermediate development. The plant hormone IAA also plays a role in this process. Furthermore, potential enzymes and regulators have been identified, including the auxin influx carrier AUX1 LAX, auxin response protein IAA13, ARF3, auxin-responsive protein SAUR50, peroxidase, and EXPs that regulate cell cycle, cell wall synthesis, as well as growth and development, were also. Based on these findings, we developed a model for castor internode elongation and gained a better understanding of the dwarfing mechanism of the 071113 variety. Our work lays a theoretical foundation for the future breeding of dwarf castor varieties. Overall design: To investigate the mechanisms behind internode elongation in the development of castor bean stems, RNA-seq was conducted on two different varieties: the dwarf-stalk 071113 and the high-stalk Zhuansihao. Each variety was subjected to three biological replications. The short-stalk 071113 samples were labeled as D1, D2, and D3, while the high-stalk Zhuansihao samples were labeled as L1, L2, and L3.