BSCL2 and infection: Because PelB and C on one hand and PelD and E on the other hand are highly similar in their amino acid sequence as well as in their enzymatic activity characteristics [35], [36], we tested the ΔpelABCDE mutant, deleted for the five genes encoding the major pectate lyases, the single mutant pelA and the double mutants pelBC and pelDE. BOS1 expression remained low after inoculation with the ΔpelABCDE and the pelBC mutants throughout the infection while a significant level increase was observed at 24 and 30 hours post infection after inoculation with the pelA or pelDE mutants.