Insecticidal CRY1B variants having improved activity spectrum and uses thereof
The disclosure provides nucleic acids, and variants and fragments thereof, derived from strains of Bacillus thuringiensis encoding variant polypeptides having increased pesticidal activity against insect pests, including Lepidoptera and Coleopteran. Particular embodiments of the disclosure provide isolated nucleic acids encoding pesticidal proteins, pesticidal compositions, DNA constructs, and transformed microorganisms and plants comprising a nucleic acid of the embodiments. These compositions find use in methods for controlling pests, especially plant pests.
1. A variant Cry1B polypeptide comprising an amino acid sequence having at least 99% sequence identity to SEQ ID NO: 63, wherein the variant Cry 1B polypeptide comprises a Leucine (L) residue at position 518 and an Arginine (R) residue at position 553, and wherein the variant Cry1B polypeptide has increased insecticidal activity against corn earworm and/or fall armyworm compared to a Cry1B polypeptide comprising SEQ ID NO: 1.
2. The variant Cry1B polypeptide of claim 1 , wherein the variant Cry1B polypeptide has increased insecticidal activity against corn earworm and/or fall armyworm compared to a Cry1B polypeptide comprising SEQ ID NO: 47.
3. The variant Cry1B polypeptide of claim 1 , wherein the variant Cry 1B polypeptide has increased insecticidal activity against corn earworm and/or fall armyworm compared to a Cry1B polypeptide comprising SEQ ID NO: 41.
4. A recombinant polynucleotide encoding the variant Cry 1B polypeptide of claim 1 .
5. The recombinant polynucleotide of claim 4 , wherein its nucleic acid sequence has been optimized for expression in a plant.
6. A DNA construct comprising the polynucleotide of claim 4 operably linked to a heterologous regulatory element.
7. A transgenic plant comprising the DNA construct of claim 6 .
8. A seed comprising the DNA construct of claim 6 .
9. A composition comprising the variant Cry1B polypeptide of claim 1 .
10. A method for controlling a Lepidopteran pest population comprising contacting said population with a pesticidally-effective amount of the variant Cry1B polypeptide of claim 1 .
11. A method for killing a Lepidopteran pest comprising contacting said pest with, or feeding to said pest, a pesticidally-effective amount of the variant Cry 1B polypeptide of claim 1 .
12. A plant or plant cell having stably incorporated into its genome the DNA construct of claim 6 .
13. A method of protecting a plant from an insect pest, comprising introducing into said plant the DNA construct of claim 6 .