CP and infection: To evaluate whether the simultaneous use of these two color-based visual markers could actually serve to monitor the infection of two different virus populations, we constructed a new TEV-crtB clone by inserting the sequence coding for crtB between the NIb and CP (coat protein) cistrons in the TEV genome, in exactly the same position as the Rosea1 gene in the TEV-Ros1 clone (Fig. 4 and Supplementary Fig. S3)7, 8.