Dual roles of pear EARLY FLOWERING 4 -like genes in regulating flowering and leaf senescence

Flowering is a critical agronomic trait in fruit tree cultivation, essential for sexual reproduction and fruit yield. Circadian clock system, governing processes such as flowering, growth, and hormone signaling, plays a key role in plant adaptability. While some clock-related genes influencing pear flowering have been studied, the role of the PbELF4 (EARLY FLOWERING 4) family remains largely unexplored. In this study, we identified five ELF4 homologous genes within the pear (Pyrus bretschneideri) genome. Phylogenetic analysis delineated two distinct groups within the PbELF4 genes, with PbELF4a and PbELF4b clustering with AtELF4. Expression profiling across various pear tissues revealed diverse expression patterns. Diurnal rhythms of PbELF4 genes were discernible in pear leaves, suggesting potential regulatory roles. Ectopic overexpression of PbELF4a and PbELF4b in Arabidopsis significantly delayed flowering and suppressed the expression of flowering-related genes. Additionally, PbELF4b overexpression induced premature leaf senescence, evidenced by reduced chlorophyll content and increased expression of senescence-associated genes. Nuclear localization of PbELF4a and PbELF4b proteins was observed, and interaction assays revealed that PbELF4a interacted with PbELF3α. These findings underscore the conserved function of PbELF4a and PbELF4b as negative regulators of flowering time, with PbELF4b also demonstrating a positive role in leaf senescence.