Molecular analysis and in vitro evaluation of transgenic Bt tomato plants against the invasive pest, Tuta absoluta (Meyrick)

Abstract

T₁ generation of transgenic Bt tomato plants (17 Nos.) was established in greenhouse to study the stability in expression of an insecticidal cry2A gene (derived from indigenous Bt isolate), over the generations. Screening was done by PCR and ELISA for finding out the presence of lepidopteran toxic cry24 gene and protein respectively. Tomato leaf miner (Tuta absoluta) is an invasive pest, damages the crop very seriously and cause 100% yield loss. The plants were evaluated in T, generation using first and second instar larvae of T. absoluta. The insect bioassay studies resulted in 43.33 to 70.00% and 43.33 to 56.67% mortality against first and second instar larvae of T. absoluta, respectively. There was significant reduction in the leaf area damage in the transgenic leaf compared to control leaf. In control, all the larvae survived and the first and second instar larvae of T. absoluta weighed approximately 2.42 mg and 3.03 mg respectively, while the surviving first and second instar larvae which fed on transgenic tomato leaves ranged from 0.19 to 0.24 mg and 0.27 to 0.33 mg, respectively. This study emphasizes the potential of the native Bt gene in imparting resistance in tomato plants against T. absoluta.