Submitted to: Potato Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/30/2014
Publication Date: 8/29/2014
Publication URL: http://handle.nal.usda.gov/10113/62724
Citation: Jones, R.W., Perez, F.G. 2014. Constituitive expression of XEGIP in potato results in phenotypic changes suggesting endogenous inhibition of cell wall growth. Potato Research. 57:133-144.
Interpretive Summary: Plants have many ways to defend themselves from attack by disease causing microbes. One way is to produce inhibitors that block the enzymes used by microbes to cause infections. One of these inhibitors was tested by developing transgenic potato plants that produced large amounts of inhibitor. While the inhibitor did not help the potato resist becoming infected, it caused large changes in the way the plant grew. This discovery provides new ideas for how plants grow, and the effect one of a plant’s own inhibitors can have on growth and development. This information will be useful for scientist studying plant cell wall growth, and for breeders selecting for new growth traits in potato.
Technical Abstract: Plant pathogens encode a large number of glycosyl hydrolases, representing many different families. Dicots are known to produce inhibitor proteins that are specific to family 12 glycosyl hydrolase members with xyloglucan-specific endoglucanase activity. The inhibitor protein, known as XEGIP, has been proposed as a defense against pathogen invasion. To test this function, multiple independent transformants of Kennebec potato were developed, using wild type and His tagged constructs. Lines resulting from constituitive production of wild type protein resulted in multiple phenotypic changes. Petioles were short and enlarged while leaves were smaller and thicker. Adventitious rooting from stem cuttings was greatly reduced and root development from sprouting tubers were also reduced. Similar effects were not seen when plants were producing His tagged protein. No change in resistance to the late blight pathogen Phytophthora infestans was seen. Phenotypic results suggest that the principal XEGIP from potato can play a previously unidentified role in regulating cell wall construction.