Functional analysis of cis-regulatory elements within the promoter of the tobacco late pollen gene g10

The tobacco gene g10 is preferentially and maximally expressed in mature po llen, shows homology to pectate lyases, and is the putative homologue of th e tomato gene lat56. Analysis of regulatory elements within the g10 promote r was carried out to verify the importance of putative regulatory sequence motifs. Analysis of transgenic plants showed that 1190 bp of g10 5' sequenc e directed preferential expression of GUS in pollen, with bimodal peaks of expression just before and during pollen mitosis I, and in mature anthers. This was confirmed by northern analysis of native g10 transcripts in isolat ed spores. Transient expression analysis defined the minimal g10 promoter r egion capable of directing expression in pollen as -86 to +217. Three upstr eam regions within -427 bp modulate the expression from g10. Gain-of-functi on analyses showed that the region from -106 to -53 could enhance pollen-sp ecific expression of a minimal CaMV 35S promoter. These analyses further sh owed that sequences upstream of -86 modulate expression in pollen, but are not essential for preferential pollen expression. The function of a conserv ed GTGA motif shared between the tobacco g10 and tomato lat56 promoters was demonstrated in g10. Thus, further functional evidence is provided for the conservation of mechanisms for the regulation of late pollen genes across species.