Exogenous Hormones Affect Bt Protein Content of Two Bt Cotton Cultivars

Abstract

Bacillus thuringiensis (Bt) transgenic cotton (Gossypium hirsutum L.) has been widely planted in Asia. However, efficacy of the Bt protein to kill pests has been inconsistent. Effects of gibberellic acid (GA3) and dimethylpiperidinium chloride (DPC) on boll Bt protein content were investigated on ‘Sikang1’ and ‘Siza3.’ Treatment of DPC increased the Bt protein contents in carpel wall and cotton seed at 10 d after flowering (DAF) and 30 DAF in 2014 and 2015. However, Bt protein contents of the GA3 treatment only at 30 DAF were higher for both cultivars in comparison to the control. To further investigate the mechanism, we found the ability of protein synthesis (indicated by enzyme activities of nitrate reductase [NR], glutamic‐pyruvic transaminase [GPT], and glutamic oxaloacetate transaminase [GOT], as well as contents of total nitrogen, free amino acid, and soluble protein) in bolls increased markedly with the application of DPC for both cultivars. Further analysis showed that there were positive linear correlations between Bt protein content and NR, GPT, and GOT activities and total nitrogen and soluble protein contents (r = 0.925∗∗, r = 0.691∗∗, r = 0.703∗∗, r = 0.682∗, r = 0.693∗∗, respectively) in carpel wall of bolls. Thus, DPC is potentially an effective chemical application to increase boll Bt protein content. Core Ideas Dimethylpiperidinium chloride (DPC) application can bolster boll insect resistance. Significant linear positive correlation between Bt protein content and ability of synthesis the protein was found in boll shell. DPC increases Bt protein content through increasing ability of synthesis the protein.

Effect of Urea Spray on Boll Shell Insecticidal Protein Content in Bt Cotton

“…Frontiers in Plant Science | www.frontiersin.org (Wang et al, 2009;Glenn, 2011;Chen et al, 2018;Zhang et al, 2019). Boll shell is the first defense for boll resistance, and bollworms attack it first in order to enter cotton bolls.…”

“…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(Chen et al, , 2018Zhang et al, 2019;Zhou et al, 2019). In addition, the application of Bt cotton effectively reduced the use of pesticides (Fang et al, 2011;Qiao et al, 2017b) and thus decreased input and environmental pollution (Sun et al, 2016).…”

The Chemical Capping Regulation Mechanism of Cotton Main Stem Growth

“…As highly active substances, plant hormones are ubiquitous in plants and participate in the regulation of the whole growth process of plants [9], and obvious effects can be observed even with trace amounts. Hormones do not act independently in plants, promoting and antagonistic effects have been observed among various hormones, which regulate plant growth and development in a systematic way [10,11]. It is well-established that auxin (IAA) can promote plant growth; Thimann et al [12] and Ljing et al [13] concluded that apical dominance-the inhibitory effect imposed by an actively growing shoot apex on axillary buds-is mediated at least in part by the synthesis and movement of auxin from young expanding leaves into the basipetal polar auxin transport stream in the main stem.…”