Genome-wide identification of CUC gene family and functional analysis of HcCUC1 in kenaf

Abstract

Abstract CUP-SHAPED COTYLEDON (CUC) is a plant-specific transcription factor that plays an important regulatory role in many aspects of plant growth and development. However, its role in kenaf (Hibiscus cannabinus L.) is largely unknown. In this study, we identified six CUCgenes from the kenaf genome and performed bioinformatics analysis. Conserved motif and gene structure analysis showed that the kenaf HcCUC genes had similar conserved motifs and highly conserved gene structure. Phylogenetic analysis showed that the six HcCUC genes could be divided into two categories: homologous to CUC2 or CUC3 of other species. Collinearity analysis showed that 6 pairs of syntenic gene pairs were formed between HcCUCgenes, and 8 pairs of homologous gene pairs were formed with three AtCUC genes of Arabidopsis. Tissue specificexpressions of the HcCUC genes was analyzed by using transcriptome data. The results showed that the HcCUC genes were differentially expressed in various tissues, mainly in the leaves of the seedling stage, buds of the mature period, and anthers at the dual-core period. Overexpression of HcCUC1 in Arabidopsis resulted in increased cotyledon length, petiole absence, and a significant increase in the number of rosette leaves and lateral branches. The qRT-PCR analysis showed that the HcCUC1 might affect leaf or lateral branch development by up-regulating the expression of auxin-related genes (YUC2, YUC4, PIN1, PIN3, PIN4) and leaf shape-related genes (KNAT2, KNAT6); In addition, overexpression HcCUC1down-regulated the expression of flowering-related genes (FT, AP1, LFY, FUL) caused the flowering delay. Taken together, these results suggest that HcCUC1 is involved in regulating leaf and lateral branch growth and development and flowering time, which can help us to understand the function and genetic regulation of HcCUC genes.