The LEA2 gene sub-family: Characterization, evolution, and potential functions in Camellia oleifera seed development and stress response

Camellia oleifera (C. oleifera) is a woody plant that is important economically due to its oil production. Late embryonic abundant (LEA) proteins are hydrophilic and thermostable proteins that accumulate during the late stages of embryo development, serving vital functions in plant development, seed oil accumulation, and stress responses. However, it remains unclear how LEAs regulate seed size, oil accumulation, and stress responses in C. oleifera. In our study, 47 LEA genes were identified across the C. oleifera genome, which were named based on their chromosomal distribution and separated into LEA2 subgroups. Ancient duplication events resulted in 3 tandem and 8 segmental duplications in the C. oleifera genome. Further analysis of genetic structure, motifs, and cis-elements demonstrated that the evolutionary relationships of the LEA gene family in C. oleifera are highly conserved with many of the LEA genes located in the chloroplast. WGCNA was used to identify modules containing co-expressed genes in different seed developmental stages, and the regulatory network revealed that CoLEA6, CoLEA26, CoLEA17, and CoLEA22 were the hub genes, acting alongside the genes involved in plant growth and abiotic stress. The qPCR analysis of 8 C. oleifera LEA genes under simulated drought stress conditions and gradient shade was conducted, and indicated that CoLEAs responded to drought and shade stresses. Overall, CoLEA22 may be critical for responses to abiotic stress and seed development. This study enable valuable insights into the roles of LEA genes in C. oleifera and establishes a foundation for further research on their function in regulating seed development, oil accumulation and stress response.