Seashore paspalum is a major warm-season turfgrass requiring frequent mowing. The use of dwarf cultivars with slow growth is a promising method to decrease mowing frequency. The present study was conducted to provide an in-depth understanding of the molecular mechanism of T51 dwarfing in the phenylpropane pathway and to screen the key genes related to dwarfing. For this purpose, we obtained transcriptomic information based on RNA-Seq and proteomic information based on iTRAQ for the dwarf mutant T51 of seashore paspalum. The combined results of transcriptomic and proteomic analysis were used to identify the differential expression pattern of genes at the translational and transcriptional levels. A total of 8311 DEGs were detected at the transcription level, of which 2540 were upregulated and 5771 were downregulated. Based on the transcripts, 2910 proteins were identified using iTRAQ, of which 392 (155 upregulated and 237 downregulated) were DEPs. The phenylpropane pathway was found to be significantly enriched at both the transcriptional and translational levels. Combined with the decrease in lignin content and the increase in flavonoid content in T51, we found that the dwarf phenotype of T51 is closely related to the abnormal synthesis of lignin and flavonoids in the phenylpropane pathway. CCR and HCT may be the key genes for T51 dwarf. This study provides the basis for further study on the dwarfing mechanism of seashore paspalum. The screening of key genes lays a foundation for further studies on the molecular mechanism of seashore paspalum dwarfing.

The use of slow-growing Seashore paspalum dwarf varieties is an effective way to reduce mowing frequency. Here, the differences in metabolism and hormone levels between Seashore paspalum dwarf mutant T51 and WT were investigated. Finally, the genes associated with the dwarf phenotype were screened in combination with our previous studies. At the metabolic level, 236 differential metabolites were identified. Further screening of hormone-related differential metabolites found that ABA and SA of T51 were increased significantly, while IAA and its intermediate metabolite indolepyruvate of T51 were decreased significantly. Endogenous hormone content assay showed that there was no difference in GA and BR content between T51 and WT; However, the IAA content of T51 was significantly reduced compared with WT. The results of exogenous hormone treatment showed that the sensitivity of T51 to exogenous hormones was IAA > GA > BR. TAA1, YUCCA, and NIT were down-regulated at both the transcriptional and protein levels; CYP79B2 and CYP79B3 were down-regulated at the protein level but had no difference at the transcriptional level. In conclusion, we propose that the down-regulated expression of TAA1, YUCCA, NIT, CYP79B2, and CYP79B3 leads to the decrease of IAA content, which is one of the important reasons for the dwarf phenotype of T51; TAA1, YUCCA, and NIT are important candidate genes related to T51 dwarf.