The N protein of Tomato spotted wilt virus: the putative elicitor of a hypersensitive response (HR) in Capsicum chinense
Lovato FA1, Nagata T, Ávila AC2, Resende RO1, Inoue-Nagata AK2
1Departamento de Biologia Celular, UnB, Bras¨ªlia, DF
2Embrapa Hortaliças, Bras¨ªlia, DF.
Correspondence: alicenag@cnph.embrapa.br
Tomato spotted wilt virus (TSWV) causes a serious disease in plants worldwide. The three genomic RNA¡äs of TSWV encode three structural proteins (L, G1/G2 and N) and two non-structural proteins (NSM and NSS). Reaction to TSWV inoculation resembling the hypersensitive response (HR) has been previously reported in Capsicum chinense ¡äPI152225¡ä and ¡äPI159236¡ä. The aim of this study was to identify the TSWV elicitor(s) protein(s) related to this HR-like response in C. chinense. For this purpose, the N, NSM and NSS genes of TSWV were cloned into the binary vector pgR107, based on Potato virus X (PVX) expression system via agroinoculation. Recombinant agrobacterium colonies transformed with the N, NSM and NSS gene constructs were inoculated into C. chinense ¡äPI159236¡ä. After 10¨C15 days, typical symptoms of PVX appeared in the upper leaves of plants inoculated with the constructions PVX+N, PVX+NSM and PVX+NSS. ELISA and Western blot confirmed the N, NSM and NSS protein expression in inoculated plants. HR-like necrotic lesions were seen only in 'PI159236' infected with the construct PVX+N. The symptomatic leaves showed typical leaf abscission after 30¨C35 days. This result indicated that the N gene of TSWV is possibly the elicitor of the HR-like response in C. chinense. In addition, leaves of C. chinense, D. stramonium and N. benthamiana inoculated with the construction PVX+NSS showed severe necrotic symptoms, suggesting an increase of PVX symptom expression caused by a possible synergism of PVX with the NSS protein. Financial Support: CNPq, Embrapa, UnB, FINATEC.
