Genome-Wide Identification and Evolutionary Analysis of the Fruit-Weight 2.2-Like Gene Family in Polyploid Oilseed Rape (Brassica napus L.)

Expression Analysis of TCP Transcription Factor Family in Autopolyploids of Chrysanthemum nankingense

Autopolyploids often exhibit plant characteristics different from their diploid ancestors and are frequently associated with altered genes expression controlling growth and development. TCP is a unique transcription factor family in plants that is closely related to plant growth and development. Based on transcriptome sequencing of Chrysanthemum nankingense, 23 full-length TCP genes were cloned. The expression of CnTCP9 was most variable in tetraploids, at least threefold greater than diploids. Due to the lack of a C. nankingense transgenic system, we overexpressed CnTCP9 in Arabidopsis thaliana (Col-0) and Chrysanthemum morifolium. Overexpression of CnTCP9 caused enlargement of leaves in A. thaliana and petals in C. morifolium, and the expression of genes downstream of the GA pathway in C. morifolium were increased. Our results suggest that autopolyploidization of C. nankingense led to differential expression of TCP family genes, thereby affecting plant characteristics by the GA pathway. This study improves the understanding of enlarged plant size after autopolyploidization.

Genome-Wide Identification and Characterization of the IGT Gene Family in Allotetraploid Rapeseed (Brassica napus L.)

IGT family genes function critically to regulate lateral organ orientation in plants. However, little information is available about this family of genes in Brassica napus. In this study, 27 BnIGT genes were identified on 16 chromosomes and divided into seven clades, namely LAZY1∼LAZY6 and TAC1 (Tiller Angle Control 1), based on their phylogenetic relationships. Duplication analysis revealed that 91.1% of the gene pairs were derived from whole-genome duplication. Most BnIGT genes had a similar structural pattern with one or two very short exons followed by a long and a shorter exon. Common and specific motifs were identified among the seven clades, and motif 1, containing the family-specific GφL(A/T)IGT sequence, was observed in all clades except LAZY5. Three types of cis-elements pertinent to transcription factor binding, light responses, and hormone signaling were detected in the BnIGT promoters. Intriguingly, more than half of the BnIGT genes exhibited no or very low expression in various tissues, and the LAZY1 and TAC1 clade members showed distinct tissue expression preferences. Coexpression analysis revealed that the LAZY1 members had strong associations with cell wall biosynthesis genes. This analysis provides a deeper understanding of the BnIGT gene family and will facilitate further deduction of their role in regulating plant architecture in B. napus.