Molecular analysis of an attenuated strain of Cucumber green mottle mosaic virus using in vitro infectious cDNA clone: pathogenicity and suppression of RNA silencing

摘要: Cucumber green mottle mosaic virus (CGMMV), a tobamovirus, infects cucurbitaceous plants including watermelon. An attenuated strain of CGMMV (CGMMV-SH33b) has been isolated from CGMMV-SH and used for protecting muskmelon against wild CGMMV. There are five nine base changes that lead to amino acid substitutions in the genome between SH SH33b: four replicase one coat protein. Using cDNA clones both strains, two recombinant were constructed: first clone (pCG-KK) (one silent at nt 5089 other P1397S substitution read-through part 186K replicase) second (pCG-SP) three 129K/186K (A1124V, N1157D P1397S). The symptom severity on Nicotiana benthamiana induced by each intermediate those SH33b. accumulation levels viruses using ELISA infected coinciding with severity. Northern blot analysis 10 dpi indicated accumulations these recombinants was order SH>pCG-KK>pCG-SP>SH33b. These results suggest located as well responsible attenuation although we cannot excluded possibility mutations involved pathogenicity. fluorescent protein gene (GFP) silenced transgenic tobacco; infection significantly suppressed GFP silencing visible symptoms, whereas CGMMV-SH33b their chimera resulted partial suppression. suppression further supported lower level mRNA higher siRNA detected SH33b leaves, than infections, suggesting N. reasonably parallel RNA mRNA.