Viruses cause great loss on crops. Identification of key gene(s) involved in antiviral immunity will provide insights for designing effective antiviral strategies on crops. Salicylic acid (SA)-signaling immunity and RNAi are two independent discovered antiviral immune pathways; however, whether the two pathways are connected remain elusive. We previously identified stress associated proteins (SAPs), Phalaenopsis Pha13, serves hubs in SA-signaling immunity. As SAPs exist as a protein family, whether duplicated SAPs have redundant or distinctive functions in antiviral immunity remains elusive. In this study, we performed functional assays on orchid Pha21, a homolog of Pha13, using transient and transgenic approaches on Phalaenopsis, Arabidopsis, and Nicotiana benthamiana to overexpress and/or silence Pha21. Our results indicated that Pha13 and Pha21 are induced by SA and transduce the SA signal to activate downstream immune responsive genes. Pha13 mainly activates the master regulator, PhaNPR1, in SA-mediated immune pathway, while Pha21 was found to play a key role in the initiation of the RNAi pathway in Phalaenopsis orchids. We provide new insight that orchid SAPs confer distinctive functions to coordinate both SA-signaling and RNAi for comprehensive activation of antiviral immunity, and this information will help us develop antiviral strategies on crops.
Li Chang, Yuh Tzean, Kuan-Ting Hsin, Chia-Ying Lin, Chun-Neng Wang and Hsin-Hung Yeh*
(2021) tress associated proteins coordinate the activation of comprehensive antiviral immunity in Phalaenopsis orchids
New phytologist, https://doi.org/10.1111/nph.17776