Exploring the functions of genes co-regulated with the ) hrpn gene of the corn pathogen Erwinia (Pantoea) stewartii

The 28 kb wts cluster of Erwinia stewartii consists of eight complementation groups including wtsE, wtsN, wtsF, wtsD, wtsA, wtsC, wtsI and wtsB. wtsA encodes a positive regulatory protein whereas the product of hrpN (wtsN) is a hypersensitive response eliciting protein. wtsE encodes an effector protein which causes water-soaking in corn. However, the functions of the wts genes in the remaining complementation groups were not known. Production and secretion of harpinEs by wts mutants was used to explore the functions of wtsF, wtsB, wtsD and wtsI. The functions of wtsF, wtsB, and wtsD were found to be export-related whereas wtsI was concluded to be regulatory.