Figure 2.

Association of cytopathic effects and biochemical lesions with macroscopic symptoms in viroid infections. (A) Schematic representation of the secondary structure predicted for a PLMVd variant inducing PC, with the nucleotides forming the PC-associated insertion denoted by a black background. (Inset) Two PLMVd (-) sRNAs mapping at this insertion target for cleavage the mRNA coding for the chloroplastic heat-shock protein 90 (cHSP90) as predicted by RNA silencing; arrow marks the predicted and validated cleavage site (Navarro et al., 2012b). (B) Accumulation of plastid rRNAs in GF-305 peach leaves infected by latent (PC-P1.149 and PC-C40Δ) and PC-inducing (PC-C40) variants as revealed by Northern-blot hybridizations with cDNA probes specific for 23, 16, 5, and 4.5S rRNAs; the impaired accumulation and processing of plastid rRNAs is associated with the albino phenotype (Rodio et al., 2007). (C) Severe chlorosis induced by a PC-inducing variant of PLMVd and (D) altered plastid with rudimentary thylakoid membranes (arrows) observed in chlorotic areas. (E) Severe chlorosis induced by ASBVd and (F) altered plastid with rudimentary thylakoid structures (arrows), slightly more organized than in PC, in the corresponding bleached areas. Bar = 50 nm. (A,B,F) have been reproduced with permissions from Navarro et al., 2012b; Copyright John Wiley and Sons), Rodio et al., 2007; Copyright American Society of Plant Biologists, www.plantcell.org) and Da Graça and Martin (1981), respectively, in all cases with permission.