Agrobacterium-mediated Genetic Transformation in Cucumber (var. Shital) as Influenced by Explant, Inoculation Time and Co-cultivation Period

Abstract

To study genetic transformation for abiotic stress resistance in cucumber (var. Shital), leaf, nodal and internodal calli were subjected to Agrobacterium tumefaciens mediated transformation using LBA4404 strain containing CIPK sense gene. Transformation ability was examined by histochemical assay of GUS reporter gene in survived calli. Conspicuous GUS positive (blue colour) region were detected in callus tissue. There were 3 factors in this investigation. Factor A consisted of three types of explants viz. leaf, nodal and internodal callus, factor B consisted of two durations of inoculation time viz. 3 and 5 min and factor C consisted of two co-cultivation periods viz. 24 and 48 hours. The highest GUS positive transgenic callus obtained from leaf explants (3.30) and internodal explants gave the lowest number (1.79) of GUS positive transformants. Inoculation time is an important factor in transformation experiment mediated by A. tumefaciens. Transformation ability was increased with increase of inoculation time. Percentage of survived callus was higher (53.68 %) when the calli were immersed for 5 min in bacterial suspension. Both number and percentage of GUS positive callus were higher (3.17 and 52.87 %, respectively) when they were kept in bacterial suspension for higher time (5 min) and lower (2.15 and 35.88 %, respectively) when calli were soaked in bacterial suspension for minimum time (3 min).