PCSK5 and infection: The expression levels of both RiBMH2 and Ri14-3-3 obviously increased accompanying the infection process and arbuscules initiation, as demonstrated by the parallel increased transcriptional levels of MtStbM1 (Figure 4E), the host plant subtilase-encoding gene which is considered as a molecular marker of arbuscular mycorrhiza development (Wegel et al., 2007; Takeda et al., 2009).