Nbnrp1 mediates Verticillium dahliae effector PevD1-triggered defense responses by regulating sesquiterpenoid phytoalexins biosynthesis pathway in Nicotiana benthamiana.

Affiliation

Liang Y(1), Li Z(1), Zhang Y(1), Meng F(2), Qiu D(1), Zeng H(1), Li G(1), Yang X(3).
Author information:
(1)The State Key Laboratory for Biology of Plant Disease and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Science, No. 2 Yuanmingyuan West Rode, Beijing 100093, China.
(2)Shandong Key Laboratory of Biophysics, Institute of Biophysics, Dezhou University, Dezhou 253023, China.
(3)The State Key Laboratory for Biology of Plant Disease and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Science, No. 2 Yuanmingyuan West Rode, Beijing 100093, China. Electronic address: [Email]

Abstract

PevD1, a fungal effector secreted by Verticillium dahliae, could induce hypersensitive responses-like necrosis and systemic acquired resistance (SAR) in cotton and tobacco plants. PevD1 could drastically induce the expression of Nbnrp1, which is an asparagine-rich protein (NRP) of Nicotiana benthamiana. Our previous research indicated that Nbnrp1 positively regulated PevD1-induced cell necrosis and disease resistance. In this study, we further investigated PevD1-induced immune responses in both wild-type (WT) and Nbnrp1-RNAi lines through RNA-seq, in order to reveal the underlying mechanism of Nbnrp1-modulated PevD1-induced disease resistance in N. benthamiana. Results showed that Nbnrp1-RNAi lines exhibited reduced PevD1-induced immune responses, like inhibiting H2O2 accumulation and MAPK phosphorylation. To silence Nbnrp1 inhibited the expression of PevD1-induced differential expression genes (DEGs) involved in pathways associated with sesquiterpenoid and triterpenoid biosynthesis, flavone and flavonol biosynthesis, plant-pathogen interaction and phenylpropanoid biosynthesis, etc. It is worth noting that sesquiterpene phytoalexin capsidiol accumulation were obviously decreased in Nbnrp1-RNAi plants after PevD1 treatment, accompanied with the down-expression of EAS and EAH, which were two key genes related to capsidiol biosynthesis. These results suggested that Nbnrp1 mediates PevD1-induced defense responses by regulating sesquiterpenoid phytoalexins biosynthesis pathway.