Relationship between the Phenylpropanoid Pathway and Dwarfism of Paspalum seashore Based on RNA-Seq and iTRAQ

Abstract

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.

Keywords: Paspalum seashore; RNA-Seq; dwarfism; iTRAQ; lignin; phenylpropanoid.

Figure 1

Phenotypic differences between WT and T51. (a) Plant types of WT and T51. (b) Leaves of WT and T51. (c) Erect stem of WT and T51.

Figure 2

(A) Expression pattern of differentially expressed genes in T51 and WT. (B) Expression pattern of differentially expressed proteins in T51 and WT.

Figure 3

Correlation analysis between differentially expressed genes and proteins in WT and T51 samples. The x-axis illustrates the expression pattern of the differentially expressed proteins (DEPs), and the y-axis illustrates the expression pattern of their corresponding DEGs in WT and T51 samples.

Figure 4

(A) Klason lignin contents. (B) Flavonoid contents. Vertical lines above the means bars indicate standard error (n = 3; p < 0.05) using Tukey’s HSD post hoc test; a,b represent significant differences between treatments.

Figure 5

Protein expression patterns of phenylpropane pathway in T51. P-coumaroyl CoA is at the crossroads of metabolic routes leading either to flavonoids or to monolignols. P-coumaroyl CoA is at the crossroads of metabolic routes leading either to flavonoids or to monolignols. PAL, phenylalanine ammonia lyase; C4H, C4-hydroxylase (CYP73A5); 4CL, 4-coumaroyl-CoA ligase; CHS, chalcone synthase; CHI, chalcone isomerase; F3H, flavanone 3-hydroxylase; FLS, flavonol synthase; ANS, anthocyanidin synthase; HCT, hydroxycinnamoyl CoA:shikimate hydroxycinnamoyl transferase; C3H, C3-hydroxylase (CYP98A3); CCR, cinnamoyl-CoA reductase; CAD, cinnamyl alcohol dehydrogenase; F5H, ferulate 5-hydroxylase (CYP84A1); CCoAOMT, caffeoyl-CoA O-methyltransferase; COMT I, caffeic acid O-methyltransferase of class I.