Poster: Plant Pathogen/Symbiont Interactions

Abs # 715: Resistance to PVX harboring GFP sequence in transgenic Nicotiana benthamiana plants with different levels of GFP silencing

Presenter:	Masamichi, Nishiguchi , mnishigu@agr.ehime-u.ac.jp
Authors	Masamichi, Nishiguchi  (A) (B)  Shimono, Masaki  (B)   Ino, Makoto  (C)   Sonoda3, Shoji  (D)   Fujimura, Tatsuhito  (C)
Affiliations:	(A): Ehime University (B): National Institute of Agrobiological Sciences (C): University of Tsukuba (D): Okayama University

Nicotiana benthamiana was transformed with a green fluorescent protein (GFP) gene driven by cauliflower mosaic virus 35S promoter. GFP silenced lines were selected by UV irradiation as well as by Southern and Northern blot analyses. One silenced line was further tested for GFP silencing and resistance to the recombined PVX harboring GFP sequence (PVX.GFP). Southern blot analysis showed three to five bands in the T1 progeny. The GFP expressed region varied from plant to plant; GFP expression in some plants was observed only in meristems and/or 1-2 young leaves (strongly silenced type I and II) and in others not only in meristems but also in stems or other leaves (weakly silenced type III). Northern blot analysis also showed different levels of GFP mRNA accumulation, from very low level in type I and II to substantial level in type III. The progeny were inoculated with PVX.GFP. No or a few GFP spots in the inoculated leaves were observed in type I and II while considerable number of spots as well as systemic infection appeared in type III and IV. These results showed that the virus resistance was clearly correlated with the strength of silencing. The quantitative analysis of siRNA accumulation is now in progress in the progeny exhibiting different levels of resistance.