Cry1Da Protein Truncation for Corn Earworm Control
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Solution Overview
Problem
Cry1Da, a delta-endotoxin produced by Bacillus thuringiensis, was previously reported to be inactive against corn earworm (CEW) larvae, but this patent describes a surprising discovery that transgenic maize expressing Cry1Da demonstrates significant insecticidal activity against CEW larvae, particularly in protecting maize silk from feeding damage.
Innovation Solution
The use of transgenic maize expressing full-length, truncated, and chimeric versions of the Cry1Da protein, which are expressed in plants to provide protection against corn earworm larvae, with superior protection observed in plants expressing truncated Cry1Da compared to commercial plants producing Cry1Fa.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Cry1Da is used to control corn earworm larvae, then protection of maize silk is improved, but previous reports indicated Cry1Da was inactive against CEW
Solution Approach 1:
The patent applies parameter changes by modifying the Cry1Da protein structure through truncation and chimeric construction. The full-length Cry1Da (1139 amino acids) was truncated to remove the protoxin portion (amino acids 1-594), and chimeric versions were created by combining Cry1Da core toxin with Cry1Ab protoxin segments. These structural parameter changes resolved the contradiction by enabling Cry1Da to achieve reliable insecticidal activity against CEW when expressed in transgenic maize, contradicting previous inactivity reports while providing superior silk protection.
2Reliability
If truncated Cry1Da is expressed in transgenic maize, then protection of maize silk is superior, but the protein structure is modified from full-length
Solution Approach 1:
The patent applies the extraction principle by removing the protoxin portion (amino acids 1-594) from the full-length Cry1Da protein to create a truncated version containing only the core toxin (amino acids 595-1139). This extraction of the essential active component achieved superior maize silk protection while eliminating potentially problematic regions. The truncated protein maintained stability and efficacy, demonstrating that the core toxin portion contains the critical functional elements for CEW control.
Solution Approach 2:
The patent applies segmentation by dividing the Cry1Da protein into distinct functional segments: the protoxin portion (amino acids 1-594) and the core toxin portion (amino acids 595-1139). By separating these segments and testing them independently, the invention identified that the core toxin segment alone provides superior silk protection. This segmentation approach also enabled the creation of chimeric proteins combining Cry1Da core toxin with Cry1Ab protoxin, further optimizing the structure-activity relationship for CEW control.
3Productivity
If transgenic maize expressing Cry1Da is used, then insecticidal activity against CEW is achieved, but Cry1Da was previously reported as inactive against this pest
Solution Approach 1:
The patent applies the copying principle by creating transgenic maize plants that express Cry1Da protein, effectively copying the bacterial toxin gene into the plant genome. This allowed the Cry1Da protein to be produced continuously within the maize tissues, particularly in the silk. The transgenic approach resolved the contradiction with prior literature by demonstrating that when Cry1Da is expressed in the correct biological context (transgenic maize rather than applied as spray), it achieves high productivity in protecting against CEW, achieving up to 100% protection in some cases.
Data Source
AI summary
The subject invention relates in part to the surprising discovery that Cry1Da is active against com earworm (CEW), Helicoverpa zea (Boddie). Methods for using Cry1Da in transgenic plants to prevent serious crop damage is described. Leaf and silk bioassays using transgenic maize expressing full length, core toxin region or chimeric Cry1Da demonstrated good insect protection against CEW larvae damage.