Poster: Transcription Regulation

Abs # 1064: Temporal and spatial expression of tomato fruit pectin methylesterase promoters in homologous and heterologous species.

Presenter:	Dominguez, Jerson R, JERSON@PURDUE.EDU
Authors	Dominguez, Jerson R (A)   Handa, Avtar  (A)
Affiliations:	(A): Purdue University

Pectin methylesterase (PME) demethoxylates methyl esterified poly-galacturonans and has been implicated in maintaining integrity of tomato fruit tissue during senescence. Chimeric gene construct containing GUS under the control of 2.7 kb and 0.4 kb DNA flanking LePME2 and 0.8 kb DNA flanking LePME3 were made to determine spatial and temporal expression of fruit PME genes. Transient expression assay for gus showed that all chimeric gene construct expressed GUS in tomato pericarp. Chimeric genes were introduced into tomato and tobacco and GUS expression was analyzed by histochemical assays in several independent transgenic plants and compared with GUS expression under the CaMV 35S promoter. All four promoter constructs expressed Gus in both tomato and tobacco seedlings. For LePME2, the 0.4 kb of 5’- flanking region imparted GUS expression higher than the 2.7 kb 5’-flanking region in 5d old, MG, BR and RR tomato fruits. GUS expression under the LePME3-0.8 kb flanking region was similar to the LePME2-0.4 kb promoter in exocarp and mesocarp, but was higher in endocarp of all stages of fruit development. LePME2-2.7 kb, LePME2-0.4 and LePME3-0.8 were active in seedlings and mature tomato plants, but higher expression was exhibited by the LePME2-0.4. In tobacco, these promoters expressed GUS in most tissuies but much higher expression in fruits. In general the LePME2 promoter provided higher expression than the CaMV 35 S. Taken together our results show that tomato PME promoter are good candidates to express foreign genes in tomato and heterologus species.