Stability of expression of Cry1Ac and Cry2Ab2 proteins in Bollgard-II hybrids at different stages of crop growth in different genotypes across cropping seasons and multiple geographies
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Bollgard-II cotton expressing Cry1Ac and Cry2Ab2 insecticidal proteins has been commercially cultivated in India since 2006 to control bollworms. These genes were introgressed into parental germplasm of numerous hybrids. Therefore, it is imperative that these insecticidal proteins are expressed in sufficient quantities in different tissues, throughout the season irrespective of genetic background or environmental conditions for effective performance. Here, we document results of a comprehensive study on pattern of expression of Bt proteins across different stages of crop growth in > 2000 cotton hybrids (Gossypium hirsutum), across 12 cropping seasons tested in the Northern, Southern or Central zones in India, in terminal leaf, pre-candle square and boll epicarp tissues. Statistical analysis of variability using Linear mixed effect model was used to estimate factors contributing to variability in expression of Bt proteins. For Cry1Ac, variability was maximally contributed by genotype × season × plant growth stage effect in terminal leaves and boll epicarp, while season effect drove variability in pre-candle square. In Cry2Ab2, season effect drove variability in three tissue types. Pre-candle square tissue had most variability in expression of both proteins followed by terminal leaf and boll epicarp. Further, expression of Bt proteins in 234 G. hirsutum × G. barbadense hybrids showed similar expression patterns as intra specific hybrids though there was a significant difference in expression levels. Cry2Ab2 was expressed in significantly higher amounts when genes were in homozygous state. Bt proteins were also found to be expressed in varied amounts in different tissues and were expressed even when hybrids were grown at sub-optimal temperatures.
KeywordsBollgard-II Bt Cry1Ac Cry2Ab2 Mathematical model
Gossypium hirsutum × Gossypium hirsutum
Gossypium hirsutum × Gossypium barbadense
Days after sowing
- S1 to S6
Sampling timepoint 1 to Sampling timepoint 6
Multi location research trial
Over the year’s various team members from Mahyco Monsanto Biotech (MMB), ELISA lab from Monsanto Research Centre, Bangalore and various Monsanto teams from Technology Development, Regulatory, Trait Introgression, Biotech, from India and US were responsible for coordinating testing requirements of this project with technology partners. The project involved movement of plant tissues to the lab, protein estimation, analysis and data compilation. Douglas Sumerford made suggestions on modelling, data interpretation and presentation. Ponnuswamy Thillaichidamba generated the figures using ‘R’ or spotfire and Shiva Prakash helped with structuring, presentation and proof reading.
ALD contributed to generating protein data, analysis, reporting along with the team and collated, cleaned the data and wrote the paper. AW was responsible for the mathematical modelling and interpretation of results. KSP interfaced with Mahyco Monsanto Biotech (MMB) and external stakeholders for testing requirements and movement of tissues to the lab, interpretation and representation of results.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
- Blaise D, Kranthi KR (2011) Cry1Ac expression in transgenic Bt cotton hybrids is influenced by soil moisture and depth. Curr Sci 101:783–786Google Scholar
- Choudhary B, Gaur K (2010) Bt cotton in India: a country profile. ISAAA series of biotech crop profiles. Ithaca, ISAAAGoogle Scholar
- James C (2015) 20th anniversary of the global commercialization of biotech crops (1996–2015) and biotech crop highlights in 2015. ISAAA Brief, 51. ISAAA, ManilaGoogle Scholar
- Kranthi S (2005) Temporal and intra-plant variability of Cry1Ac expression in Bt-cotton and its influence on the survival of the cotton bollworm, Helicoverpa armigera (Hubner)(Noctuidae: Lepidoptera). Curr Sci 89:291–298Google Scholar
- Kranthi KR (2015) Cotton statistics and news. Cotton Assoc India 35:1–6Google Scholar
- Malik W, Ashraf J, Iqbal MZ, Ali Khan A, Qayyum A, Ali Abid M, Noor E, Qadir Ahmad M, Hasan Abbasi G (2014) Molecular markers and cotton genetic improvement: current status and future prospects. Sci World J Artic ID 607091:1–15Google Scholar
- Poongothai S, Ilavarasan R, Karrunakaran CM (2010) Cry 1Ac levels and biochemical variations in Bt cotton as influenced by tissue maturity and senescence. J Plant Breed Crop Sci 2:96–103Google Scholar
- Puja Mondal (2016) Cotton cultivation in India: conditions, types, production and distribution. Available at http://www.yourarticlelibrary.com/cultivation/cotton-cultivation-in-india-conditions-types-production-and-distribution/20949/
- R Core Team (2016) R: a language and environment for statistical computing. R Foundation for Statistical Computing, Vienna, Austria. Available at https://www.R-project.org/
- Ramasundaram P, Vennila S (2013) A decade of Bt cotton experience in India: pointers for transgenics in pipeline. Curr Sci 104:697–698Google Scholar
- Rana MK, Bhat KV (2005) RAPD markers for genetic diversity study among Indian cotton cultivars. Curr Sci 88:1956–1961Google Scholar
- Reddy M, Hunje R, Biradar DP, Vyakarnahal BS (2010) Characterization of cotton hybrids and parental lines using morphological characters. Karnataka J Agri Sci 20:511–513Google Scholar
- Singh AK, Paritosh K, Kant U, Burma PK, Pental D (2016) High expression of Cry1Ac protein in cotton (Gossypium hirsutum) by combining independent transgenic events that target the protein to cytoplasm and plastids. PLoS ONE 11:1–17Google Scholar