Use the information provided in the experiment below to annotate/ label the figure. Background: Boll weevil is a serious pest of cotton crop. Effective control involves applications of chemical insecticides, increasing the cost of production and environmental pollution. The current genetically modified Bt crops have allowed great benefits to farmers but show activity limited to lepidopteran pests. This work reports on procedures adopted for integration and expression of a cry transgene conferring resistance to boll weevil and fall armyworm by using molecular tools. Four Brazilian cotton cultivars were microinjected with a minimal linear cassette generating 1248 putative lines. Complete gene integration was found in only one line (TO-34) containing one copy of crylla detected by Southern blot. Protein was expressed in high concentration at 45 days after emergence (dae), decreasing by approximately 50% at 90 dae. Toxicity of the cry protein was demonstrated in feeding bioassays revealing 56.7% mortality to boll weevil fed buds and 88.1% mortality to fall armyworm fed leaves. A binding of crylla antibody was found in the midgut of boll weevils fed on TO-34 buds in an immunodetection assay. The gene introduced into plants confers resistance to boll weevil and fall armyworm. Transmission of the transgene occurred normally to TI progeny. All plants showed phenotypically normal growth, with fertile flowers and abundant seeds. Results relating to figure: In feeding bioassays, fall armyworm larvae and boll weevil adults were fed on tissues of T0-34 plants over a period of 7 days in order to estimate the mortality rates due to crystal ingestion. For fall armyworm, mortality of larvae was verified 24 h after the beginning of feeding. In most cases, more than 50% of the larvae had died after the 4th day (Fig. 6B). The mortality rate after 7 days was 88.1% . In the boll weevil bioassays, mortality of adults was seen at 48 h after boll feeding. At first, the insects moved slowly in the corner of the pots (Figs 6F and G), and they died the next day in the ‘head up’ position (Fig. 6H). The mortality rate was higher in leaves (83.7%) than in buds (56.7%). These results were expected, as the promoter used in construction (CaMV 35S) has limited expression in flower buds. On the other hand, the LC50 of the recombinant Cry1Ia protein tested in previous feeding bioassays was lower for fall armyworm (0.29 μg mL−1) than for boll weevil (21.5 μg mL−1). The T1 lines with positive amplicons shown in Fig. 6 were all self-fertilised, and T2 plants were submitted to feeding bioassays with fall armyworm and boll weevil insects

Use the information provided in the experiment below to annotate/ label the figure. Background: Boll weevil is a serious pest of cotton crop. Effective control involves applications of chemical insecticides, increasing the cost of production and environmental pollution. The current genetically modified Bt crops have allowed great benefits to farmers but show activity limited to lepidopteran pests. This work reports on procedures adopted for integration and expression of a cry transgene conferring resistance to boll weevil and fall armyworm by using molecular tools. Four Brazilian cotton cultivars were microinjected with a minimal linear cassette generating 1248 putative lines. Complete gene integration was found in only one line (TO-34) containing one copy of crylla detected by Southern blot. Protein was expressed in high concentration at 45 days after emergence (dae), decreasing by approximately 50% at 90 dae. Toxicity of the cry protein was demonstrated in feeding bioassays revealing 56.7% mortality to boll weevil fed buds and 88.1% mortality to fall armyworm fed leaves. A binding of crylla antibody was found in the midgut of boll weevils fed on TO-34 buds in an immunodetection assay. The gene introduced into plants confers resistance to boll weevil and fall armyworm. Transmission of the transgene occurred normally to TI progeny. All plants showed phenotypically normal growth, with fertile flowers and abundant seeds. Results relating to figure: In feeding bioassays, fall armyworm larvae and boll weevil adults were fed on tissues of T0-34 plants over a period of 7 days in order to estimate the mortality rates due to crystal ingestion. For fall armyworm, mortality of larvae was verified 24 h after the beginning of feeding. In most cases, more than 50% of the larvae had died after the 4th day (Fig. 6B). The mortality rate after 7 days was 88.1% . In the boll weevil bioassays, mortality of adults was seen at 48 h after boll feeding. At first, the insects moved slowly in the corner of the pots (Figs 6F and G), and they died the next day in the ‘head up’ position (Fig. 6H). The mortality rate was higher in leaves (83.7%) than in buds (56.7%). These results were expected, as the promoter used in construction (CaMV 35S) has limited expression in flower buds. On the other hand, the LC50 of the recombinant Cry1Ia protein tested in previous feeding bioassays was lower for fall armyworm (0.29 μg mL−1) than for boll weevil (21.5 μg mL−1). The T1 lines with positive amplicons shown in Fig. 6 were all self-fertilised, and T2 plants were submitted to feeding bioassays with fall armyworm and boll weevil insects

Biology 2e

2nd Edition

ISBN:9781947172517

Author:Matthew Douglas, Jung Choi, Mary Ann Clark

Publisher:Matthew Douglas, Jung Choi, Mary Ann Clark

Chapter24: Fungi

Section: Chapter Questions

Problem 22RQ: Why are fungal insecticides an attractive alternative to chemical pesticides for growing food crops?...

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