Delivery of N-methyltransferase and 11S globulin promoters of Coffea canephora Pex Fr. by tissue electroporation and analysis of transformational events

A tissue electroporation system was optimized to deliver
transgenes, and the expression of reporter gene driven
by coffee N-methyltransferase (NMT) and 11S globulin
promoters in somatic embryos of Coffea canephora
was achieved. Plant transformation vector pCAMBIA
1301 was adopted for electroporation. Transient as well
as stable expression of uidA gene was detected after
electroporation using field strengths of 500 V/cm, 900 F
capacitance and 100 g/ml of plasmid DNA. The efficiency
of tissue electroporation was dependent on the
type and developmental stage of the plant material.
Spermidine treatment during electroporation increased
transformation frequency twofold. Histochemical staining
of GUS activity confirmed the expression of uidA
gene in somatic embryos and endosperm tissues of C.
canephora. Electroporation with pPCGB 959 (11S
globulin promoter) resulted in 32% of explants showing
GUS expression in endosperm tissues. The study
demonstrated the ability of these promoters to drive
the expression of the reporter gene. The results may
be helpful for using these promoters to alter the
expression of the NMT gene family through transcriptional
gene silencing by RNA-directed DNA methylation,
and also for using 11S globulin promoter for
silencing NMT genes in a tissue-specific manner in
transgenic coffee plants.