Evolutionary Insights and Flowering Regulation of <i>SPLs</i> in Coconut Palm
Runan Chen,
Yalan Feng,
Jin Zhou,
Ying Wang,
Fengyi Zhang,
Shazia Rehman,
Zhuang Yang,
Zifen Lao,
Hang Xu,
Yong Xiao,
Jie Luo,
Wei Xia
Affiliations
Runan Chen
State Key Laboratory of Topical Crop Breeding, School of Breeding and Multiplication (Sanya Institute of Breeding and Multiplication)/School of Tropical Agriculture and Forestry, Hainan University, Sanya 572025, China
Yalan Feng
State Key Laboratory of Topical Crop Breeding, School of Breeding and Multiplication (Sanya Institute of Breeding and Multiplication)/School of Tropical Agriculture and Forestry, Hainan University, Sanya 572025, China
Jin Zhou
State Key Laboratory of Topical Crop Breeding, School of Breeding and Multiplication (Sanya Institute of Breeding and Multiplication)/School of Tropical Agriculture and Forestry, Hainan University, Sanya 572025, China
Ying Wang
State Key Laboratory of Topical Crop Breeding, School of Breeding and Multiplication (Sanya Institute of Breeding and Multiplication)/School of Tropical Agriculture and Forestry, Hainan University, Sanya 572025, China
Fengyi Zhang
State Key Laboratory of Topical Crop Breeding, School of Breeding and Multiplication (Sanya Institute of Breeding and Multiplication)/School of Tropical Agriculture and Forestry, Hainan University, Sanya 572025, China
Shazia Rehman
State Key Laboratory of Topical Crop Breeding, School of Breeding and Multiplication (Sanya Institute of Breeding and Multiplication)/School of Tropical Agriculture and Forestry, Hainan University, Sanya 572025, China
Zhuang Yang
State Key Laboratory of Topical Crop Breeding, School of Breeding and Multiplication (Sanya Institute of Breeding and Multiplication)/School of Tropical Agriculture and Forestry, Hainan University, Sanya 572025, China
Zifen Lao
State Key Laboratory of Topical Crop Breeding, School of Breeding and Multiplication (Sanya Institute of Breeding and Multiplication)/School of Tropical Agriculture and Forestry, Hainan University, Sanya 572025, China
Hang Xu
State Key Laboratory of Topical Crop Breeding, School of Breeding and Multiplication (Sanya Institute of Breeding and Multiplication)/School of Tropical Agriculture and Forestry, Hainan University, Sanya 572025, China
Yong Xiao
State Key Laboratory of Topical Crop Breeding, School of Breeding and Multiplication (Sanya Institute of Breeding and Multiplication)/School of Tropical Agriculture and Forestry, Hainan University, Sanya 572025, China
Jie Luo
State Key Laboratory of Topical Crop Breeding, School of Breeding and Multiplication (Sanya Institute of Breeding and Multiplication)/School of Tropical Agriculture and Forestry, Hainan University, Sanya 572025, China
Wei Xia
State Key Laboratory of Topical Crop Breeding, School of Breeding and Multiplication (Sanya Institute of Breeding and Multiplication)/School of Tropical Agriculture and Forestry, Hainan University, Sanya 572025, China
Squamosa Promoter-Binding Protein Like (SPL) is a critical transcription factor that plays a significant role in regulating plant growth and development. Mining the coconut SPL family offers valuable insights into the regulation of important agronomic traits, including the length of the juvenile phase. In this study, 25 CnSPLs were identified and were classified into eight subfamilies. Analysis of gene structure and conserved protein motifs indicated a high conservation of CnSPLs within the same subfamilies; however, variations in protein structure and gene length were observed across different subfamilies. Gene expansion analysis indicated that most gene members within subfamilies originated from duplications of the same genomic segment, and transposable element insertion contributed to the divergence of gene sequences within these subfamilies. Characterization of the miR156 target sequence in SPL transcripts revealed that subfamilies IV to VIII contained these sequences, while subfamilies I to III did not. In both coconut and 14 other plant species, some SPLs lost their miR156-binding loci due to gene structure variations. The gene expression profiles revealed significant divergence between miR156-targeted and non-targeted CnSPLs; the former exhibited low expression levels in the endosperm, while the latter showed comparable expression across all tissues. Notably, CnSPL15A demonstrated steadily increasing expression levels in leaves throughout successive leaf primordia and significantly promoted flowering when overexpressed in Arabidopsis. Transient expression assays and 5′ RACE confirmed that CnSPLs are targeted by miR156. This study establishes a foundation for investigating the evolutionary characteristics of CnSPLs and provides a theoretical framework for analyzing the functions of key CnSPLs involved in the coconut flowering control pathway.
