We suggest that viroids are trapped into adaptive peaks as the result of adaptive constraints. The first one is imposed by the necessity to fold into packed structures to escape from RNA silencing. This creates antagonistic epistases, which make future adaptive trajectories contingent upon the first mutation and slow down the rate of adaptation. This second constraint can only be surpassed by i...

sweet lime split bark is a disorder of increasing importance in fars province. previously we showed that a new variant of hop stunt viroid (hsvd-sb) was related to the disorder. it had homology with a noncachexia variant of hop stunt viroid (cvd-iia-117) which causes cracking the bark of trifoliate orange rootstocks. in this study, showed that m.ngobix, bgli and bsri restriction enzymes can cut...