Abstract
Reproductive organs of Bacillus thuringiensis transgenic cotton, which contribute to cotton final yield, have low insect resistant efficacy, so it is important to improve their insect resistance. This study was conducted to find out the impact of different urea spray doses on the expression of Cry1A protein in boll shell of Bt cotton (Sikang 1 and Sikang 3), and nitrogen metabolism in this process was also studied to uncover the physiological mechanism. The experiment with six urea doses was organized during peak boll stage in 2017 and 2018. The results showed that urea spray could significantly increase boll shell insecticidal protein contents in both cultivars, with the highest Bt protein content observed at 28–32 kg ha−1 urea dose. In addition, urea spray increased the contents of soluble protein and free amino acid and the activities of GS, GOGAT, GOT, and GPT, but decreased the activities of peptidase and protease in boll shell. Correlation analysis showed that the amount of boll shell Bt protein was positively correlated with levels of soluble protein and amino acid, and activities of GS, GOGAT, GOT, and GPT, but negatively correlated with peptidase and protease activities. Thus, this study demonstrated that higher protein synthesis ability and lower proteolysis ability were related to increased Bt protein content in urea-sprayed boll shell.
Highlights
Bacillus thuringiensis transgenic cotton (Bt cotton) is the cotton cultivar with insect resistance, which is obtained by transferring Bt toxin gene from B. thuringiensis into cotton (Ma et al, 2020)
The results showed that urea spray could significantly increase boll shell insecticidal protein contents in both cultivars, with the highest Bt protein content observed at 28–32 kg ha−1 urea dose
A greater increase of Bt protein content in the boll shell was detected under 36 kg·ha−1 urea, with an increase of 35.48% in Sikang 1 and 26.56% in Sikang 3 compared to untreated control at 20DAF in 2017
Summary
Bacillus thuringiensis transgenic cotton (Bt cotton) is the cotton cultivar with insect resistance, which is obtained by transferring Bt toxin gene from B. thuringiensis into cotton (Ma et al, 2020). In the whole process of growth and development of Bt cotton, all tissues and organs can express insecticidal protein, which can effectively reduce the harm of cotton bollworm and other related pests (Chen et al, 2005, 2018; Zhang et al, 2019; Zhou et al, 2019). The results of Dai’s study indicated that the application of nitrogen can increase the expression of insecticidal protein, so as to effectively alleviate the decrease of insect resistance of Bt cotton in late growth stage (Dai et al, 2012). Studying the relationship between urea application and insecticidal protein content of boll shell is quite important to improve the insecticidal ability of cotton bolls. The objective of this study was to ascertain the effects of spraying different urea doses on the expression of insecticidal protein, and nitrogen metabolism in this process was studied to uncover the potential mechanism
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
