FIG. 1.

Silencing of the hsp70-white transgene in line HS-2 is suppressed by known Su(var) mutations. (A) Map of the P-element construct used. The 3′ and 5′ P-element ends (black boxes), hsp26 gene fragment (hatched box), pt (barley gene) fragment (blue box), termination signal (white box), hsp70 promoter region (cross-hatched box), and white gene fragment (red box) are diagrammed. (B) Control line 39C-X carries the P element in a euchromatic site, while HS-2 has the P element inserted into pericentric heterochromatin. The HS-2 transgene shows loss of silencing in the presence of the Su(var)2-5⁰² and Su(var)3-7 mutations, while expression of the 39C-X transgene is unaffected.