Genome-Wide Analysis of SPL/miR156 Module and Its Expression Analysis in Vegetative and Reproductive Organs of Oil Palm (Elaeis guineensis)

The SPL (SQUAMOSA-promoter binding protein-like) gene family is one of the largest plant transcription factors and is known to be involved in the regulation of plant growth, development, and stress responses. The genome-wide analysis of SPL gene members in a diverse range of crops has been elucidated. However, none of the genome-wide studies on the SPL gene family have been carried out for oil palm, an important oil-yielding plant. In this research, a total of 24 EgSPL genes were identified via a genome-wide approach. Phylogenetic analysis revealed that most of the EgSPLs are closely related to the Arabidopsis and rice SPL gene members. EgSPL genes were mapped onto the only nine chromosomes of the oil palm genome. Motif analysis revealed conservation of the SBP domain and the occurrence of 1–10 motifs in EgSPL gene members. Gene duplication analysis demonstrated the tandem duplication of SPL members in the oil palm genome. Heatmap analysis indicated the significant expression of SPL genes in shoot and flower organs of oil palm plants. Among the identified EgSPL genes, a total 14 EgSPLs were shown to be targets of miR156. Real-time PCR analysis of 14 SPL genes showed that most of the EgSPL genes were more highly expressed in female and male inflorescences of oil palm plants than in vegetative tissues. Altogether, the present study revealed the significant role of EgSPL genes in inflorescence development.