Simultaneous silencing of CaNAC2c and CaNAC2dsignificantly inhibited resistance of pepper plant to RSI
The silencing of CaNAC2c did not produced obvious symptoms upon
RSI, while its overexpression in pepper and N. benthamiana plants
did promoted immunity against RSI, implying that CaNAC2c may function
redundantly with other genes in response to RSI. As CaNAC2dshares the highest sequence identity to CaNAC2c and exhibited
similar upregulation in response to RSI (Figure S2), we speculate that
it might act redundantly with CaNAC2c in pepper response to RSI.
To test this hypothesis, we assay the effect of simultaneous silencing
of CaNAC2c and CaNAC2d on response of pepper plants to RSI
and HTS. The result showed that the silencing of CaNAC2d alone
did not significantly affect either pepper thermotolerance or immunity
against RSI (Figure 7A), while CaNAC2c and CaNAC2dsimultaneously silenced pepper plants exhibited obvious wilt soymptoms
at 192 hpi when inoculated with R. solanacearum , and the highest
disease index from 2 to 12 dpi, while their individually silenced plants
did not exhibit obvious wilt soymptoms (Figure 7B-E).The simultaneous
silencing of CaNAC2c and CaNAC2d and their silencing alone
pepper plants exhibited enlarged size compared to the control
plants(Figure S10). Consistently, the thermotolerance relatedCaHSP24 , CaHSP70 and CaHSFB2a were not
downregulated by silencing of CaNAC2d , their transcript levels inCaNAC2c silencing were similar to that in CaNAC2c andCaNAC2d simultaneously silenced pepper plants (Figure 7F). By
contrast, transcript levels of CaDEF1 were not downregulated by
silencing of either CaNAC2c or CaNAC2d , but was
significantly decreased by simultaneous silencing of CaNAC2c andCaNAC2d, indicating that CaNAC2c and CaNAC2dfunction redundancy in pepper immunity against RSI mediated by JA
signaling.