Genome-wide analysis of Class III peroxidase (PRX) family core genes and functional mechanism of GhPRXR1-A for seed development in Gossypium hirsutum.

Class III peroxidases (PRXs) play critical roles in plant growth and development by oxidizing various substrates with HO. Although many PRXs have been identified and their roles in biotic and abiotic stress responses have extensively investigated in plants. However, functional mechanisms of PRXs in seed development remain poorly understood. In this study, 14, 17, 9, and 13 PRX core genes were identified in Gossypium hirsutum, Gossypium barbadense, Gossypium arboreum, and Gossypium raimondii, respectively. Phylogenetic analysis categorized PRXs core genes of cotton into five groups. Six of the GhPRX genes co-localized with quantitative trait loci (QTLs) associated with oil or seed size, and GhPRXR1-A showed significant high expression levels in developing ovules. Heterologous overexpression of GhPRXR1-A in Arabidopsis thaliana resulted in a significant increase in thousand seed weight (Col-0: 0.015 ± 0.00085 g vs. OE-GhPRXR1-A: 0.022 ± 0.0019 g). In addition, molecular mechanism assays revealed that GhPRXR1-A is directly activated by GhGATA1 and interacts with GhNFYC4, a transcription factor of the nuclear factor Y, C subunit family that has previously been reported to mediate seed development. Collectively, these findings suggest that GhPRXR1-A is a regulator of seed development in Arabidopsis and may have similar functional role in cotton seed contributing traits.