Efficient Agrobacterium-mediated in planta genetic transformation of watermelon [Citrullus lanatus Thunb.]

The production of transgenic watermelon through Agrobacterium tumefaciens-mediated transformation with in vitro regeneration system is a time-consuming, labor-intensive and genotype-dependent process. To acquire large number of transgenic watermelons in a shorter period of time, the half-seed explants were infected with Agrobacterium strain EHA 105 harboring pCAMBIA1301 with bar and gus genes. The factors affecting in planta transformation efficiency, such as co-cultivation duration, acetosyringone concentration, sonication duration and vacuum infiltration were assessed in the present study. The half-seed explants were sonicated for 3 min and 2 min vacuum infiltrated in Agrobacterium suspension and co-cultivated for 3 days with 100 µM acetosyringone showed maximum transformation efficiency. The transformed watermelon plants were selected against BASTA® and GUS, PCR, Southern hybridization analysis confirmed the transgene integration. The amenability of this established protocol was analyzed on four genotypes, in which the response of all genotypes was positive, whereas Arka manik showed the higher transformation efficiency of 17%. The transformation protocol developed in the present study is efficient, economical and expeditious without the taking part of any tissue culture phases and produce a large number of transgenic lines within a short period of 56 days.