10.22376/ijpbs.2019.10.1.p1-12 Volume 5 Issue 1 2014 (January - March) Optimization of co-cultivation parameters during lessThan i greaterThan Agrobacterium lessThan /i greaterThan –mediated transformation to lessThan i greaterThan Cassia occidentalis lessThan /i greaterThan (Linn) evaluated were bacterial density, infection period, wounding and pre-culture of explants, acetosyringone (AS) concentration and co-cultivation temperature. Some of the parameters optimized and resulted in high transformation efficiency were as follows; lessThan i greaterThan Agrobacterium tumefaciens lessThan /i greaterThan growth phase of A lessThan sub greaterThan 600nm lessThan /sub greaterThan 0.17, infection period of 30 min, addition of acetosyringone (AS) in co-cultivation medium (400µM) and in bacterial growth culture. Higher bacterial density resulted in more transformation efficiency, but also higher necrosis in the explants. Dilution of bacterial suspension reduced necrosis in explants and resulted in higher transformation. The transformation efficiency at co-cultivation temperature 25 lessThan sup greaterThan o lessThan /sup greaterThan C was 193 GUS-positive spots per explant and it was increased 6 fold when the infection process was carried out with acetosyringone in co-cultivation medium (400µM) and in bacterial culture (50µM).Our studies proved that among the optimized conditions; the concentration of acetosyringone was the critical parameter during co-cultivation process in lessThan i greaterThan Agrobacterium lessThan /i greaterThan mediated transformation. MUSTRAHALLY RAJAGOPAL, AVULAMANDHA BALAKRISHNA, SADDALA RAJESWARA REDDY AND BATHULA SRINIVAS Agrobacterium tumefaciens, Cassia occidentalis, gus gene. 840-855