Abstract:Cucurbita ficifolia Bouche. is a unique cucurbits germplasm resource in Yunnan Province with highly Fusarium wiltresistance genetic trait. To explore the function of NBSLRR type genes from C. ficifolia, in this study, we isolated the NBS type gene of CfRFN2 (GenBank ID:MK618462). We obtained a full length 4 303 bp by divided three fragment cloning using RTPCR method from leaves of C. ficifolia. The CfRFN2 gene was annotated as a homologous gene of transcriptionoid X1 of Arabidopsis diseaseresistant protein At4g27190, with complete coding frame length of 4 092 bp and encoding 1 363 amino acids, and its deduced protein contained one NBARC conserved domain and two LRR domains. The CfRFN2 gene belongs to a hydrophilic protein containing the signal peptide. The results of nucleotide similarity analysis indicated that the identity of CfRFN2 gene varied from 87% to 98% when compared with the other disease resistance genes in Cucurbitaceae crops. Phylogenetic analysis results showed that CfRFN2 protein and other NBS type protein from cucurbits crops were clusterd into one branch, indicating it had closer genetic relation among cucurbits crops than with other species NBS protein. Moreover, CfRFN2 had the closest genetic relation with RPS2 of Cucurbita pepo and Cucurbita moschata, Cucurbita maxima RPS2like protein, followed by Cucurbita sativus At4g27190 and Momordica charartia At4g27220, while relatively quite far from Cucurbita melo At4g27190. The tissue specific expression results indicated that the CfRFN2 gene was highly expressed in leaves than that in stems, and had low expression level in fruits and roots. Furthermore, based on the tobacco rattle virus vector system, we also constructed VIGS silencing vector pTRV2CfRFN2, constantly the seedlings of C. ficifolia were infected by Agrobacterium tumefaciens carrying silencing vector and inoculated with Fusarium oxysporum after 4 weeks infection (wild type plants inoculation pathogeny simultaneously). The qRTPCR analysis showed that, compared to the wild type plant, the expression of CfRFN2 gene in silencing plants decreased by 34.75% and 98.27%, respectively after 2 and 4 days inoculation. Moreover, the average disease index of silencing plants was 1.32 times that of wild type plants. This preliminarily results suggested that CfRFN2 gene in C. ficifolia had the function of resistance to Fusarium wilt. The cloning and VIGS confirmation of NBS type gene CfRFN2 would be the basis for digging more disease resistant genes in C. ficifolia, and thus provide a new clue for carrying out molecular breeding and exploring the disease resistant mechanism in cucurbits crops.