Pyramiding of AtEDT1/HDG11 and Cry2Aa2 into pepper (Capsicum annuum L.) enhances drought tolerance and insect resistance without yield decrease

Improvement of biotic and abiotic stress tolerance without yield decrease has been a great challenge in vegetable breeding. Functional stacking of multiple resistant genes could potentially be an effective strategy against more different stress. Here, we report that constitutive co-expression of Arabidopsis thaliana homodomain-leucine zipper transcription factor Enhanced Drought Tolerance/HOMEODOMAIN GLABROUS11 (AtEDT1/HDG11) and Bacillus thuringiensis Cry2Aa2 was able to increase pepper drought tolerance and insect resistance. More importantly, fruit yield was improved under both normal and drought stress conditions. The improved tolerance to drought stress was associated with improved root system and reduced stomatal density. Compared to the non-transgenic control, the transgenic pepper plants also had higher levels of chlorophyll content, chlorophyll fluorescence (Fm/Fv), proline, soluble sugar, abscisic acid, and ROS scavenging capacity under dehydration stress conditions. The increased flower number, elevated fruit weight, and improved fruit number all contributed to the increased yield of transgenic pepper. In addition, bioassays showed that the transgenic plants were effective to control the Prodenia litura, producing a mortality rate of 81.3 % after 5 days of infection. Therefore, our study indicates that stacking of AtEDT1/HDG11 and Cry2Aa2 in pepper plants can improve drought tolerance and insect resistance, demonstrating application of AtEDT1/HDG11 and Cry2Aa2 has the potential to enhance drought tolerance and insect resistance.