Complex regulatory network of Betula BplSPL8 in planta.

SQUAMOSA-promoter binding protein-like (SPL) proteins are plant-specific transcription factors and participate in different pathways, including the vegetative to reproductive transition, male sterility, biosynthesis of gibberellic acid (GA), plant morphogenesis and response to environmental stress. In this study, we generated transgenic Arabidopsis that overexpressed Betula BplSPL8 and confirmed that BplSPL8 is a transcription factor with transcriptional activation activity and is located in the nucleus. Functional analysis of BplSPL8 showed that it is involved in regulating different development processes: (1) BplSPL8 can delay flowering by reducing sensitivity to GA under short days; (2) BplSPL8 controls the number and morphogenesis of leaves, including up-rolling leaves under long days and folded leaves mediated by GA under short days; (3) BplSPL8 can promote root elongation during late development of roots and inhibit lateral root formation; (4) BplSPL8 may be involved in regulating carotenoid biosynthesis and secretion metabolism. These results show that there is a complex regulatory network for the SPL family genes that is mediated by other components and may provide a new insights for the functional research of SPL genes. [ABSTRACT FROM AUTHOR]