A second set of XEGIP-encoding genes resides on chromosome 8 of potato and tomato

Xyloglucan-specific endoglucanase inhibitor proteins (XEGIPs) are present in a wide range of dicots, where they are believed to play a role in defense from pathogens. XEGIPs are generally present as two or three copies; however, they are reported to be present as a cluster of 10 copies in potato and tomato on chromosome 1. We have identified a second set of XEGIP-encoding genes, where two inverted copies are present on chromosome 8 of potato (Solanum tuberosum L.). The same set exists in the same order on chromosome 8 of tomato (Solanum pennellii Correll). Transcript expression analysis indicates that XEGIP10 is transcribed only in roots, while XEGIP11 transcripts were not detected under normal growth conditions. Transformed potatoes (‘Bintje’ and ‘Kennebec’) overexpressing these genes did not show any changes in phenology. Foliar screening of transgenic lines for resistance to the late blight pathogen Phytophthora infestans (Mont.) de Bary did not demonstrate a large reduction in disease progression or p...