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United States Department of Agriculture

Agricultural Research Service

Title: THE LOSS OF EXPRESSION OF THE H GENE IN BT TRANSGENIC POTATOES

Author
item Brodie, Bill

Submitted to: American Journal of Potato Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 28, 2002
Publication Date: N/A

Interpretive Summary: The golden nematode is a serious threat to the potato industry of the United States as it can cause up to 80% loss in potato yields if left uncontrolled. A strict quarantine and statutory control program has kept the golden nematode below plant damaging level and has limited its presence to six countries in New York State. Resistant potato varieties are the primary means of golden nematode control in the statutory program. Becaus resistant varieties are grown in rotation with susceptible varieties, it is extremely important to monitor resistant varieties to ascertain their golden nematode resistance through the seed multiplication process. During routine monitoring of resistant varieties from the seed production program that are used in the statutory control program, we discovered that the golden nematode developed on the transgenic variety Atlantic NewLeaf. Further investigations determined that Atlantic NewLeaf possessed the gene for golden nematode resistance but the gene was not expressed which would result in golden nematode population increase rather than the expected decrease. These results suggests the need to focus on unintended outcomes during pre-release testing of transgenic plants. In particular, testing should include the effects of transgene insertion on major traits such as disease and pest resistance that have been bred into parental lines.

Technical Abstract: During evaluation of potato clones and cultivars from the Cornell seed production program to confirm their resistance to Globodera rostochiensis (golden nematode) pathotype Ro1, several cysts developed on the transgenic cultivar Atlantic NewLeaf. This transformed cultivar resulted from the insertion of the Bt endotoxin gene into the golden nematode resistant cultivar Atlantic. In subsequent bioassay tests, golden nematode cysts developed freely on this transgenic cultivar that originated from Atlantic NewLeaf clone 6 but not on Atlantic NewLeaf clones 31 and 36 that were from different Bt transformation events of the cultivar Atlantic. RFLP analysis of the cultivar Atlantic that was used in the transformations and the transgenic Atlantic NewLeaf clones 6, 31, and 36 showed that they all possessed the marker for the H1 gene that confers resistance to the golden nematode pathotype Ro1. These data indicate that at some point in the Bt transformation process the expression of the H1 gene was affected in clone 6 of the transgenic cultivar Atlantic NewLeaf. This finding highlights the importance of pre-release evaluation of transgenic plants for any previously known resistance traits before they are released for commercialization.

Last Modified: 8/27/2014
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