Priorities of breeding approaches in bt cottons.dr. yanal alkuddsi
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The document discusses the breeding approaches in Bt cotton, emphasizing the transformation with Bacillus thuringiensis (Bt) cry proteins to enhance pest resistance and productivity. It outlines the adoption and performance of Bt cotton in India and the various hybrids developed over the years, as well as the need for improved combining ability in breeding for greater efficiency. Additionally, the document highlights the challenges in fiber quality and micronaire value affecting Indian Bt cotton and compares it with conventional varieties.
![Table 3.General combining ability effects of parents (lines and testers) in respect of
kapas yield and its attributing characters of cotton[G .hirsutum L.]
LINES Bolls per plant
Mean boll
weight(g) Kapas yield
(g / plant)
Ginning
Per cent
1 0.10 0.00 -0.76 -0.67
2 2.00 * -0.21 * -2.02 -2.20 *
3 3.57 ** -0.07 5.43 -1.61
4 3.49 ** 0.06 14.00 ** 2.19 *
5 -6.56 ** 0.40 ** -3.20 1.61
6 -2.60 ** -0.19 -13.45 ** 0.68
S.Em.± 0.86 0.09 3.06 0.86
CD ( ĝ i – ĝ j) at 5% 2.45 0.27 8.72 2.46
CD ( ĝ i – ĝ j ) at 1%
3.26 0.36 11.62 3.28
TESTERS
1 -0.53 -0.16 -7.27 * -1.80
2 -2.30 * 0.11 8.64 * -1.70
3 1.25 -0.02 1.96 -2.42 *
4 -1.33 -0.29 * -14.18 ** 0.24
5 -2.17 * 0.30 ** -3.24 2.64 *
6 0.23 0.06 1.85 -0.53
7 3.47 ** -0.04 3.86 1.62
8 1.38 0.04 8.38 * 1.95
S.Em.± 0.99 0.11 3.54 0.99
CD ( ĝ i – ĝ j ) at 5%
2.82 0.31 10.07 2.84 8/13/201637](https://image.slidesharecdn.com/prioritiesofbreedingapproachesinbtcottons-160813203734/85/Priorities-of-breeding-approaches-in-bt-cottons-dr-yanal-alkuddsi-37-320.jpg)
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Priorities of breeding approaches in bt cottons.dr. yanal alkuddsi
- 2. 2 Priorities of Breeding Approaches in Bt Cottons 8/13/2016 8/13/2016
- 3. Dr.Yanal Ahmad Al-kuddsi Biotechnology Researcher Department of Biotechnology General Commission for Scientific Agricultural Research Damascus – Syria http://dr-yanal-alkuddsi.strikingly.com
- 5. 8/13/2016 5
- 6. 6 8/13/2016 Bacillus thuringiensis (Bt) - Cry stalline proteins are classified according to structure & have a specific nomenclature (e.g., Cry1Ac) - Cotton has been transformed with Cry1Ac (narrow spectrum; Lepidoptera only) - Protein binds with receptors in the insect gut causing pores which perforate the midgut & lead to cell leakage & insect death Control Bt boll Cotton Boll Damage Protected Cotton Boll 8/13/20166
- 7. 8/13/20167
- 8. Classification of insecticidal BT proteins. 8/13/20168 Cry IA Cry IB Cry IC Cry IIA CryIIB Cry IIIA Cry IVA Cry IVB Cry IVC Cry IVD Caterpillars Caterpillars Caterpillars Caterpillars / Fly larvae Fly larvae Beetle larvae Fly larvae Fly larvae Fly larvae Fly larvae 133.2 138.0 134.8 70.9 70.8 73.1 134.4 127.8 77.8 72.4 GeneType Insect Host Size (kD)
- 9. 9 The Transformation The gene of interest is spliced out of the bacterium using a vector, like Agrobacterium tumefasciens, & transferred to cotton cells grown in tissue culture The cells are grown into a plant & then, after testing, plants are back-crossed into commercial lines to make new varieties Recurrent back-crossing 8/13/2016 9
- 10. Conventional plant breeding Desired gene Commercial varietySource variety / species Result By comparison, biotechnology offers more precise plant breeding... X Modern biotechnology 8/13/201610
- 11. Bt cotton…………….Why? •To reduce use of chemical pesticides •To increase production and productivity • Ecofreindly • Reduce risk to farmers 8/13/201611
- 12. Non Bt era Bollworm Square loss Additional vegetative growth No translation into sink Reduction of harvest index Reduction in yield Bt Cotton Reduce the cost of protection Preventing the loss of Square vegetative growth translated into matching Increase in reproductive growth Improvement of harvest index Increasing in yield Fig.1 Comparison between Bt cotton and non Bt cotton 8/13/201612
- 13. Scenario of Bt Cottonin India 8/13/201613
- 14. 14 Adoption of Bt cotton in India, by major state, from 2002 to 2009 (thousand hectares) 8/13/201614
- 15. 15 Cotton production and productivity during Non Bt and Bt era 0 100 200 300 400 500 600 97- 98 98- 99 99- 00 00- 01 01- 02 02- 03 03- 04 04- 05 05- 06 06- 07 07- 08 08- 09 Production Productivity Non Bt era Bt era 8/13/2016 15
- 16. 16 Bt cotton hybrids approved for commercial cultivation Year Cry1Ac (Mon 531) Cry1Ac + 2Ab (Mon 15985) Cry1Ac (Event 1) Cry1Ab+ Cry1Ac (GFM event) Cry1Ac (Truncated) 2002 3 - - - - 2004 1 - - - - 2005 16 - - - - 2006 24 7 8 3 - 2007 56 13 4 3 - 2008 44 73 7 18 1 Total 144 93 19 24 1 Source: GEAC, MOEF,GOI. 8/13/2016 16
- 17. A list of Bt cotton events approved for cultivation in India 8/13/201617
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- 19. 8/13/201619
- 20. Most popular G. hirsutum hybrids Until 2002, about 50 hybrids were released. In the past 5 years >500 G. hirsutum Bt hybrids have been released. The area under hybrid cotton is about 90% in 2009. 8/13/201620
- 22. Improving Productivity of Hybrids Bt gene is now part of the genetic background •In few years of Bt era – over Six hundred of Bt cotton hybrids are released – Just Handful of them are popular •Ultimately it’s the genetic potentiality for productivity that determines success of a Bt genotype •Breeding efforts of improving genetic potentiality of Bt cottons assumes greater importance 1 8/13/2016 22
- 23. Boll Number Boll Weight SEED COTTON YIELD Path of Productivity 8/13/201623
- 24. SEED COTTON YIELD Boll Number Bolls on Monopodia Monopodia length No. of Monopodia Bolls per monopodia Bolls on Sympodia No. of Sympodia Sympodia length Bolls per Sympodia Other Traits Rejuvination Stay green nature Subtending Leaf Photosynthesis Stay green nature Leaf Thickness (SLW) Boll Weight Locule No. Locule Weight No. of Seeds Seed Weight GOT % Boll Harvest Index Kapas Wt/(KW + Rind Weight 8/13/201624
- 25. - Glabrousness - Light green leaf - Plant pigmentation long pedicel - Cream petal - Smaller bract - High gossypol on gland - High tannin Genotype requirement – Bt cotton in India 8/13/201625
- 26. Developing diverse Heterotic Popuations Exploiting them by Following Recurrent schemes of Improving Combining ability (Increasing Genetic distance) and Enhancing Heterosis Maintaining such populations Distributing them to breeders Such Schemes are Integral part of Hybrid breeding in Cross pollinated crops Can we Implement this concept in Cotton ? 8/13/201626
- 27. 8/13/201627
- 28. Understanding Combining Ability Pattern of Cotton Genotypes and Forming Heterotic Groups Evaluation of Crosses involving Diverse Cotton genotypes at different centres is a Continuous Process (over a decade) Utilize this Data +Their Performance in national trials - Insight in to Combining ability pattern (behaviour) of varietal lines – HelpsTo Form Heterotic groups and Understand basis of Heterosis 8/13/201628
- 29. Which Crosses are so far observed to be most Potential ? Some crosses with diversity for plant types Robust vs Compact are producing potential crosses Complimenting Physiological Traits such as High Photosynthetic Source genotypes (Stay green types) crossed to genotypes having better Tanslocation efficiency (Harvest Index ) , High RGR, Early maturing types Though diverse types give potential hybrids at the same time Some combinations involving apparently similar types may also produce very potential crosses 8/13/201629
- 30. High RGR/HI Group Bushy/Robust Group Stay Green Group Compact Group These Intergroup Crosses found to be equally productive Potential Additional heterotic groups without conspicuous phenotypic differences are also formed 8/13/201630
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- 33. Improving combining ability through reciprocal selection Derived F4/F5 Lines Derived F4/F5 Lines X X cross II or its parents (C &D) cross I or its parents( A&B) Cross I (A x B) Cross II (C x D) Derived F1s compared with straight crosses and commercial checks (Assessment of improved combining ability ) 8/13/201633
- 34. Estimating combining ability effects and forming heterotic pools for exploitation in cotton (Gossypium hirsutum L.) Y.A.Alkuddsi et al ,.2009 There is a constant need to develop more potential hybrids and adopt noval approaches for improving hybrid performance. In cross pollinated crops like maize heterotic populations are developed and exploited through population improvement schemes meant for improving combining ability. 8/13/201634
- 35. Table1: List of cotton lines and testers in the study of combining ability Lines Testers L1- RAH 318 T1- SC 14 L2- RAH 243 T2- SC 18 L3- RAH128 T3- SC 7 L4- RAH146 T4- SC 68 L5- RAH 97 T5- RGR 32 L6- RAH 124 T6- RGR 24 T7- RGR 58 Bushy/Robust Group Compact Group 8/13/201635
- 36. Table 2. Mean performance of experimental hybrids and and sca effects and gca effects of parents for different characters. Sl No. Crosses Bolls per plant Mean boll Weight (g) Kapas yield (g/plant) Ginning per cent Per se performanc e Sca effects Per se performan ce sca effects Per se performan ce Sca effects Per se performan ce sca effects 1 YHH36 (L5T2) 16.1 1.16 3.52 0.04 139.96 62.53 ** 35.74 0.14 2 RCH2 Bt 31.6 3.32 107.58 32.25 3 YHH 134 (L4 T8) 29.5 0.83 2.89 -0.19 106.18 11.81 36.87 -3.91 4 YHH 133 (L4 T7) 33.8 3.05 2.98 -0.02 104.9 15.05 41.37 1.63 5 YHH 106 (L1 T6) 33.2 9.07 ** 2.98 -0.05 103.6 30.53 ** 35.06 0.56 6 YHH 129 (L4 T3) 31.1 2.56 2.87 -0.15 95.26 7.31 36.23 0.82 7 YHH 112 (L2 T 3) 31.4 4.35 2.91 0.17 91.61 19.69 * 31.6 0.33 8 YHH 123 (L3 T6) 31.1 3.49 2.97 0.01 91.16 11.89 31.38 -2.35 9 BUNNY Bt 26.4 3.3 91.14 34.88 10 YHH 124 (L3 T7) 30.1 -0.74 2.97 0.10 89.2 7.92 36.09 0.59 11 YHH 115 (L2 T 6) 28.5 2.47 3.05 0.23 89.09 17.27 33.44 0.45 12 YHH 131 (L4 T 5) 25.9 0.78 3.44 0.10 88.96 6.21 42.23 1.51 13 YHH 108 (L1 T8) 26.1 0.82 3.08 0.06 86.53 6.93 37.31 5.88 * 14 YHH 107 (L1 T7) 31.3 3.93 3.23 0.29 82.33 7.24 36.54 -0.10 15 RAHH 95 30.6 2.31 68.15 37.54 8/13/201636
- 37. Table 3.General combining ability effects of parents (lines and testers) in respect of kapas yield and its attributing characters of cotton[G .hirsutum L.] LINES Bolls per plant Mean boll weight(g) Kapas yield (g / plant) Ginning Per cent 1 0.10 0.00 -0.76 -0.67 2 2.00 * -0.21 * -2.02 -2.20 * 3 3.57 ** -0.07 5.43 -1.61 4 3.49 ** 0.06 14.00 ** 2.19 * 5 -6.56 ** 0.40 ** -3.20 1.61 6 -2.60 ** -0.19 -13.45 ** 0.68 S.Em.± 0.86 0.09 3.06 0.86 CD ( ĝ i – ĝ j) at 5% 2.45 0.27 8.72 2.46 CD ( ĝ i – ĝ j ) at 1% 3.26 0.36 11.62 3.28 TESTERS 1 -0.53 -0.16 -7.27 * -1.80 2 -2.30 * 0.11 8.64 * -1.70 3 1.25 -0.02 1.96 -2.42 * 4 -1.33 -0.29 * -14.18 ** 0.24 5 -2.17 * 0.30 ** -3.24 2.64 * 6 0.23 0.06 1.85 -0.53 7 3.47 ** -0.04 3.86 1.62 8 1.38 0.04 8.38 * 1.95 S.Em.± 0.99 0.11 3.54 0.99 CD ( ĝ i – ĝ j ) at 5% 2.82 0.31 10.07 2.84 8/13/201637
- 38. Table 4. Identifying diverse pairs of crosses based on predicted performance of double cross combinations T 2 T 3 L4 78.48 95.26 L5 139.96 66.52 T 7 T 8 L1 82.33 86.53 L4 104.9 106.18 PREDICTED MEAN (L4 T8) 106.18 (L4T7) 104.9 (L1 T8) 86.53 (L1 T7) 82.33 MEAN 94.985 PREDICTED MEAN (L4 T2) 78.48 (L5T2) 139.96 (L4 T3) 95.26 (L4 T3) 66.52 MEAN 95.06 8/13/201638
- 39. Conclusion - The performance of three top hybrids viz., hybrid YHH 133, YHH 134, YHH 136 in respect of kapas yield needs to be verified for their performance on large scale basis. - The results implies that the line 4 and the tester 5 studied were high combiners across all the traits, indicating their ability in transmitting additive genes in the desirable direction to their progenies. Further, these line and tester can be tested for the confirmation of their superiority as good parents for hybridization 8/13/201639
- 40. Quality of Cotton in Released Bt hybrids 2 8/13/201640
- 41. India cottons are considered to possess inappropriate micronaire value for aspecific staple owing to poorly developed cell wall in fibres occasioned by immaturity resulting in weaker fibres. The hybrids have been also found to be prone to immaturity with subsequent pickings leading to immature and weaker fibres. Concerted efforts and due to a very strong demonstrative programme of integrated pest management, it has been possible to improve significantly the micronaire status in most of the popularly traded cottons . 8/13/201641
- 42. 8/13/201642
- 43. The tenacity of indian cottons , which continue to remain lower even after sustained efforts in quality improvement. Indian cottons are assessed for quality using the HVI in the ICC mode unlike in the west where HVI mode is the normal operating mode where the tenacity is invariably pushed up about 25 %. The fibre mironaire has a predominant influence in deciding the tenacity in the HVI mode. 8/13/201643
- 44. 8/13/201644
- 45. The fibre quality seems to be not a criteria under scrutiny before the release of Bt hybrids in India, although Bt lint has been noted to be cleaner and fluffy. After handling for a few years, by now mills perspective about processing of Bt cottons is that the micronaire value of the cotton to begin with is considerably higher than what normally indian cottons possessed prior to Bt release. The deterioration in micronaire value in the case of Bt hybrid is much steeper compared to the conventional hybrid. The extra long staple erosion in the country has already been known even before the Bt release. 8/13/201645
- 46. Comparative performance of Bt cotton with some elite conventional cotton cultivars under arid to semi-arid conditions 8/13/201646 Four cotton cultivars , CIM-496, BH-162,VH-144 and Bt- 121. To compare yield potential, quality traits and disease resistance of Bt and non-Bt cotton cultivars under arid to semi-arid climatic conditions. Ahsan Aziz et al., 2011
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- 53. Conclusion 8/13/201653 Bt-121 with medium plant height gave better yield in arid climatic conditions because of abundant sunshine and better response of short statured cultivars to high doses of fertilizers. The virus infection is a major hurdle for yield improvement in cotton crop and the cultivars which showed resistance against virus infection are preferred for general cultivation as compared to susceptible varieties (Khan et al., 1993). Variation in seed cotton weight per boll among cotton genotypes may arise from variation in photosynthetic capacity, as well as partitioning of these assimilates to various parts of the plant body.
- 54. 8/13/201654 All the four cotton cultivars differed in maturity percentage and that the performance of Bt-121 was better than other cultivars used for comparison. LSD comparison showed significant differences among four cotton varieties, depicting that BH-162 had maximum fiber fineness as compared to other varieties. Variation in fiber length was found within a cultivar or even within a single boll. Uniformity in staple length improves spinning performance. High fiber strength is difficult to obtain without sacrificing yield. CultivarVH-144 produced very strong fibers but its seed cotton yield was the lowest indicating that, this quality trait might have been influenced by the yield potential of a cultivar.
- 55. Challenges of Bt Cotton 8/13/201655
- 56. 56 Is Bt gene affecting only boll worms ? Bt gene produces poisonous protein to kill bollworm. Is it causing any other effect on the plant? YES It induces even every early square to get converted into a boll ! The capacity of sink is thus enhanced! There is no evidence for it’s source being enhanced by Bt gene! Is the increased sink’s capacity realized? What is the impact of this on the Source? Is the plant phenology capable of sustaining enhanced sink? 8/13/201656
- 57. 57 Impact of Bt gene on the relation between vegetative and reproductive phase of growth in cotton” Patil S. S et al., 2010 “Correlated Impact” Introduced Bt Gene Any impact on source? Inducing every square to bear a boll Is it capable of bearing this extra load? Enhancement of sinks capacity Is this increased sink’s capacity realized? Is the plant phenology capable of sustaining enhanced sink? 8/13/2016 57
- 58. 58 Objectives - Evaluation of plant type, productivity and physiological traits of Bt cotton hybrids - Analyzing and interpreting causes for the differences in productivity of these Bt cotton hybrids. 8/13/2016 58
- 59. 59 Productivity features of Bt cotton hybrids No. of entries : 15 Rep. no. : 2 Harvest index Yield (Kg/ha) Total Yield (Kg/ha)Entry name Boll No. Boll wt. LH UH LH UH Hybrid 1 31.5 4.9 0.31 0.32 2458 2269 4726 Hybrid 2 41 6.1 0.31 0.32 2385 2202 4587 Hybrid 3 33 5.1 0.32 0.31 2303 2213 4517 Hybrid 4 34.5 5.1 0.32 0.31 2299 2209 4507 Hybrid 5 31.5 4.9 0.3 0.31 2236 2191 4427 Hybrid 6 42.3 6.2 0.3 0.31 2175 2131 4306 Hybrid 7 37.2 5.6 0.29 0.28 2110 2196 4305 Hybrid 8 35.7 5.4 0.33 0.32 2147 2147 4294 Hybrid 9 39.7 5.9 0.29 0.23 2684 1510 4194 Hybrid 10 30.8 4.3 0.29 0.23 2628 1478 4106 Hybrid 11 46.5 6.8 0.31 0.23 2522 1545 4067 Hybrid 12 37.3 5.6 0.32 0.25 2474 1516 3990 Hybrid 13 44.7 6.6 0.32 0.25 2403 1537 3940 Hybrid 14 35.5 5.2 0.28 0.21 2154 1377 3530 Hybrid 15 33.5 5.2 0.28 0.21 2081 1025 3106 8/13/2016 59
- 60. 60 No. of entries : 15 Replication : 2 Entry Plant height Monopodia no. Sympodia no. S L @ 50% Rep. point IBD Hybrid 1 179.2 2.5 19.5 55.2 5.0 15.43 Hybrid 2 212.3 3.3 22.3 63.6 5.2 17.77 Hybrid 3 196.8 2.5 16.8 52.8 4.5 14.60 Hybrid 4 197.8 3.2 25.3 88.3 4.8 24.20 Hybrid 5 176.8 3.2 23.8 51.9 4.5 14.97 Hybrid 6 186.5 3.0 23.8 59.9 4.3 16.97 Hybrid 7 159.8 3.5 21.8 53.5 5.0 15.20 Hybrid 8 180.7 2.5 20.0 52.2 4.7 14.70 Hybrid 9 175.2 3.3 19.7 53.0 5.7 14.90 Hybrid 10 220.3 2.8 23.2 56.6 5.3 16.07 Hybrid 11 212.8 2.2 26.7 56.1 4.5 16.23 Hybrid 12 193.3 2.8 23.5 55.3 4.2 15.80 Hybrid 13 178.3 2.2 18.3 92.2 5.3 24.57 Hybrid 14 194.0 2.3 24.5 50.5 5.7 14.67 Hybrid 15 176.8 2.2 23.2 54.2 4.3 15.47 Plant type features of Bt cotton hybrids 8/13/2016 60
- 61. 61 The impact of enhanced Sink With same photosynthetic output (source) the quantum of sink has increased Some genotypes lack matching photosynthetic potential (source) to meet extra demand of Sink They cannot cope with this drain. Leaves are weakened, subsequent reddening, disease incidence and senescence In some hybrids there is Mismatch between source and sink at a later stage of growth (upper half of the plant) 8/13/2016 61
- 62. Physiological changes in Bt cotton Leaf area Index Slightly reduced - Photosynthetic rate Increased slightly - Harvestable Bolls Increased Boll weight Increased Harvest index Increased Boll growth /maturity Synchronous Habit Determinate Duration Reduced Senescence Faster Sink 8/13/201662
- 63. 63 Strata Yield Harvest Index Upper half Low Low Lower half High High Because physiological impact of Bt background was not visualized while developing them 8/13/2016 63
- 65. 65 STAY GREEN Higher Photosynthetic ability, higher leaf area, Stay green nature become very important in overcoming this mismatch 8/13/2016 65
- 66. 66 Overcoming the demand of enhanced sink induced due to Bt gene Chemical intervention Genetic intervention 1.Ethrel spray Enhancing Source to meet the demand of enhanced sink Physiological Intervention Ethylene spray is expected to induce initial square dropping causing additional vegetative growth making the plant competent to bear enhanced sink 8/13/2016 66
- 67. 67 - Often non Bt hybrid genotypes are selected based on potentiality and the parents are subjected to transfer of Bt gene through back cross breeding - It is very important to know whether the genotype chosen for Bt gene has ability to withstand the additional reproductive load (sink). If the enhanced sink is not matched by the source( mismatch between source and sink ) this is reflected in the form of faster senescence reduced boll load especially in the upper half of the plant. - These genotypes which lack matching photosynthetic potential (source) wither under the pressure of enhanced sink. Inference in Plant Breeding 8/13/2016 67 Results :
- 68. 68 - This impact is often noticed in the latter half of the growth. As a result, the harvest index and seed cotton yield are reduced in upper half of the plant. - Some hybrids of non –Bt era , which on developing Bt version are clearly showing weaker upper half since they cannot cope with this drain. - The symptoms of weakened leaves, more prone to reddening, disease incidence and senescence are noticed commonly. This is leading to reduced boll load and lower harvest index in the upper half as compared to lower half 8/13/2016 68
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- 71. Armyworms on Cotton BractFeeding at Base of Boll Damage to Inside of Boll 8/13/201671
- 72. Damaged Square: Bt CottonEconomically Damaged Square Bollworm in Bloom Tag Color Phases of Beet Armyworms on Cotton Flower 8/13/201672
- 73. While transfering Bt gene through Backcross breeding Grow progeny rows in backcross generation Select for recurrent parents constitution and retain or Reject plants resembling donor parents Grow recurrent and donor parents along with backcross progenies Develop such a donor as Bt source which has distinct phenotypic marker traits helping in rejecting plants in backcross generations 8/13/201673
- 74. Breeding for Sucking pest tolerance Sucking pests cause maximum damage in Bt cottons Conventional Mechanisms ofTolerance to Biotic Stresses Increased tannin content, palisade layer features etc.,. Antagonastic traits like hairiness of leaf can be freely used to impart sucking pest tolerance Introgression of traits from related species to cultivated cottons a) Desi cottons to hirsutums b)Other related species to hirsutums 8/13/201674
- 75. Bollgard II Cotton Benefits Insect resistance management Increased control of targe pests Reduced insecticide application Control Bollgard Cotton Boll Damage Cotton Boll Protected Monsanto,USA Bollgard I – event 531 – cry 1 Ac Bollgard II- event 15985 cry 1 Ac + cry 2 Ab 8/13/201675
- 76. Safety - Resistance .Given time & exposure, insects have the capacity to overcome most insecticides. Bt cotton may be no different, however, there are safeguards: .Refugia .High-Dose Strategy .Development of additional protein 8/13/201676
- 77. Refugia •Objective: provide harborage for susceptible moth production to reduce the chance of resistant (R) moths mating with each other •U.S. growers are required to plant a proportion of their acreage to non-Bt cotton • 5% Refuge, if no lepidopteran-active insecticides are used on it, or else 20% Refuge RR RR RR SS RR RS SS 8/13/201677
- 79. 8/13/201679
- 80. Can other host species of cotton bollworm be non-Bt refuges to prolong the effectiveness of Bt-cotton? TAN Shengjiang et al.,2001 • In China Bt-cotton is inter-planted with many other host species of H. armigera, and the migration ability of this insect specie is strong. •An effective refuge strategy that maximizes the probability that susceptible individuals arising from a structured refuge will find and mate with the resistant individuals that survive exposure to the delta endotoxin produced in the Bt-plant. 8/13/2016 80
- 81. 8/13/201681
- 83. 8/13/201683
- 84. Result Field investigation indicated that the third and fourth generations of cotton bollworm can survive from the Bt-cotton, and chemical insecticides are needed to reduce the damage. The population on Bt-cotton differentiated genetically from those on the other host species. Both maize and castor-oil plant can be refuges as normal cotton to produce susceptible individuals and to prolong the effectiveness of Bt-cotton. 8/13/201684
- 85. Survival and reproduction of natural populations of Helicoverpa armigera on Bt-cotton hybrids in Raichur, India M.T. Ranjith,A. Prabhuraj andY. B. Srinivasa 2010 • Individuals of Helicoverpa armigera, the most prominent among bollworms in India. • Commercial Bt-cotton hybrids containing single (Cry1Ac) and double (Cry1Ac and Cry2Ab) genes in experimental plots of the University of Agricultural Sciences, Raichur campus, India. • NCS-145 and MRC-7918 Cry1Ac and Cry2Ab genes (BollgardTM-II,Event MON 15985) hybrids •MRC-6918 Cry1Ac gene (BollgardTM-I, Event MON 531) hybrid). •MRC-7918 (non-Bt) is similar to MRC-7918. 8/13/201685
- 86. Figure 1. Desigen Bt expression strips® exhibiting double bands indicating the presence of Cry toxins in different plant parts of Bt hybrids. 8/13/201686 Figure 2. Larva of Helicoverpa armigera feeding on boll of Bt hybrid.
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- 89. Conclusion Results on the developmental biology from the F0 generation do not clearly suggest any particular pattern. All the larvae collected on MRC-7918 successfully pupated,whereas 75% of the larvae collected on NCS-145 and 70% on non-Bt hybrid pupated. The trends obtained cannot be attributed to either the presence or absence of Cry genes in the hybrids. It can be inferred that the performance of individuals of H. armigera on the Bt hybrids is ‘comparable’ to those on the non-Bt hybrid. We further enquired whether the next generation (F1) was able to successfully complete its development on particular hybrids. 8/13/201689
- 91. YES, by anyone's definition of a public good. Bt is a public good because it is a natural resource, a part of the biotic community, that has evolved over the millennium shaped by the forces of nature. It is a biological resource that serves uniquely valuable functions within biotic communities, both in natural systems and those managed by humans. It is a product of organisms widely dispersed in nature, owned by no one. Is Bt a "public good"? 8/13/201691