The gram-negative bacterium Acetobacter xylinum synthesizes an extracellular ribbon of cellulose microfibrils that possess unique structural and mechanical properties when compared to higher plant cellulose. All four genes in the cellulose-synthesizing operon (ayacs operon) of A. xylinum Ay201 were amplified by polymerase chain reaction (PCR) using oligonucleotide primers designed according to published acs operon sequence of A. xylinum ATCC 53582. Alignment of the two operons showed that they were highly homologous (98% similarity, 97% identity). AcsA and acsB gene were cloned in pCAMBIA 1301 vector while acsC and acsD were cloned in pCOB302-3 under the control of CaM 35S promoter. The constructs were introduced into cotton by the pollen-tube-pathway method and seeds obtained from putative transgenic plants were germinated on media containing hygromycin and phosphinothricin (PPT). Five seedlings out of 934 seeds were proved to contain all four foreign genes by PCR amplification. This is the first time that a whole operon encoding four different bacterial enzymes with various biological functions is transformed into cultivated cotton plants.
