Transcriptomic and proteomic analyses of far-red light effects in inducing shoot elongation in the presence or absence of paclobutrazol in Chinese pine

In angiosperms, low red (R)/far-red (FR) ratio light increases gibberellin (GA) levels. GA signaling in conifer seedlings requires FR to promote shoot elongation and reduce the inhibition of shoot elongation induced by paclobutrazol (PAC), yet the effects of far-red light in inducing shoot elongation in the presence or absence of PAC is poorly understood. In this study, transcriptomic and proteomic analyses was used to examine the molecular mechanism of FR regulation of shoot elongation in Chinese pine (Pinus tabuliformis Carr.) seedlings in the presence of PAC. Four treatments were compared: white light + water (WW), FR + water (RW), white light + PAC (WP), and FR + PAC (RP), and 1436 differentially expressed genes (DEGs) and 450 differentially expressed proteins (DEPs) were identified in RW_WW (RW contrast WW), and 1862 DEGs and 481 DEPs in RP_WP (RP contrast WP). Metabolic and signal transduction pathway analyses of DEGs and DEPs in RW_WW and RP_WP, indicated that the former required more energy than the latter. Moreover, gibberellic acid, auxin, and brassinolide are equally important in RW_WW and RP_WP for shoot elongation, except for the ethylene pathway. Amino acid metabolism and cell wall organization were significantly enriched in RW_WW and RP_WP, respectively. In summary, RW_WW and RP_WP had different effects in secondary metabolism, energy metabolism, amino acid metabolism, cell wall organization, and hormone response. These results provide an important theoretical and reference basis for studying the regulatory effect of low R/FR and PAC in conifer shoot elongation.