Spatio-temporal regulation of the OsHFP gene promoter establishes the involvement of this protein in rice anther development

Abstract

Anther development leading to pollen maturation, anther dehiscence and pollen dispersal depends upon the precise timing of programmed cell death (PCD) in specified anther tissues. The PCD necessitates a properly tuned transcriptional regulation of some crucial genes. However, the detailed genetic regulation of this PCD in rice anther is yet to be deciphered. Recently, we have established that the OsHFP, a structurally novel hemopexin fold protein of rice is a flower-specific heme binding protein, and plays a role in chlorophyll degradation. Here, we report the spatio-temporal transcriptional regulation of the OsHFP gene, which is proposed to be involved in anther PCD. The OsHFP was immunodetected in rice anthers, and OsHFP-related proteins were also found to be present in anthers of other monocot (lily) and dicot (tobacco) plant species. Unique cis-acting elements, possibly involved in the activation and anther-specificity of the OsHFP promoter were identified based upon in silico prediction and in planta expression profiling of the reporter gene driven by the OsHFP promoter (2051bp) and its two deleted versions (1057bp and 437bp). The temporal regulation of the OsHFP promoter in different developmental stages of tobacco anther implies the physiological function of this protein in anther PCD.