Albertus Eskes

Transient expression of β-glucuronidase following biolistic delivery of foreign DNA into coffee tissues.

Some conditions related to the transient expression of β-glucuronidase in biolistically-treated Coffea spp. tissues were investigated, and subsequently used in a promoter study. Bombardments were performed on different types of tissue (leaves, somatic embryos and suspension cultures) of genotypes of C. arabica, C. canephora and Arabusta, using 4 different promoter sequences. Tobacco leaves were used as a comparison. In general, similar large variation and mean values of transient expression were observed between coffee and tobacco leaves. With regard to the coffee tissues effect, transient expression was best detectable and most frequently observed with bombarded leaves of microcuttings. Disturbing endogenous light blue staining was found with control treatments of somatic embryos. For the three coffee species tested, the most effective promoter was the EF1α-A1 promoter of Arabidopsis thaliana.

Glufosinate as an efficient inhibitor of callus proliferation in coffee tissue

SummaryTo improve selection of transgenic Coffea spp. tissue after transformation treatments, the effects of the selective agents chlorsulfuron, glufosinate, glyphosate, hygromycin, and kanamycin were studied on callus development from leaf explants (from greenhouse-grown plants and somaplants) and in embryogenic suspension cultures. Studied genotypes were from C. arabica, C. canephora, and the interspecific hybrids Arabusta and Congusta. A culture system based on “direct” somatic embryogenesis from C. canephora leaf explants proved to be more sensitive to selective agents than high frequency somatic embryogenesis from C. arabica or Arabusta leaf explants. With respect to the selective effect, chlorsulfuron and hygromycin provoked strong inhibition and severe necrosis, whereas glyphosate and kanamycin showed variable inhibition. Glufosinate appeared to efficiently inhibit growth of both leaf callus and callus suspensions of all genotypes tested without inducing necrosis. These properties may make the use of glufosinate advantageous in a selective growth system for detection of transformed coffee tissues.