Pyramiding of Bt cry1Ia8 and cry1Ba3 genes into cabbage (Brassica oleracea L. var. capitata) confers effective control against diamondback moth

A binary vector carrying Bacillus thuringiensiscry1Ia8 and cry1Ba3 genes was introduced into an inbred line of white cabbage by Agrobacterium tumefaciens-mediated transformation for control of diamondback moth (DBM, Plutella xylostella), and 14 kanamycin-resistant plantlets were obtained. Presence and expression of the cry1Ia8 and cry1Ba3 genes in five transformed plants were confirmed by polymerase chain reaction (PCR), Southern blot, reverse transcription-polymerase chain reaction (RT-PCR), and Western blot analyses. Insect bioassays showed that these transgenic plants were able to effectively control both susceptible and Cry1Ac-resistant DBM larvae as compared to non-transformed counterparts. Ten homozygous insect-resistant cabbage lines were obtained in the T2 generation through self-pollination, and molecular methods and insect bioassays. After natural infestation under greenhouse and field conditions, the pyramided lines exhibited excellent efficacy against DBM. Furthermore, data from field trials indicated that there were no significant differences in most agronomic traits between most the homozygous lines and the original variety. These transgenic lines may allow field study of resistance management strategies involving gene pyramiding and serve as novel insect-resistant resources in cabbage breeding.