The original isolate of bz-rcy displays a fine-high spotting pattern in the presence of the Cy regulatory element (Schnable and Peterson, MGN58:9). Numerous states of the receptor element have been rescued from this original isolate which differ in the timing, frequency and tissue specificity of their mutability.

Two cycling states of bz-rcy have been characterized that arose out of bz-m805137, the original isolate of bz-rcy. bz-rcy824325w has a low pattern of late mutations. In aleurone tissue events occur which signal bz-rcy824325w to cycle back to a high state resulting in clusters of frequent mutations surrounded by regions of low frequency spotting (Figure 1). No germinal reversions to a high state have been observed.

bz-rcy812215 shows a reduced frequency of spotting in aleurone tissue when compared to the original bz-rcy isolate. In contrast to bz-rcy824325w no reversions to a high state occur in aleurone tissue (Figure 2). However, germinal reversions to a high state occur among approximately 1% of the Cy-containing bz-rcy812215 gametes. These high states are phenotypically indistinguishable and heritable. Ear sectors of reversion have been observed demonstrating that reversions of bz-rcy812215 can occur early in ear development but not in aleurone tissue.

Figure 1. The pattern conditioned by bz-rcy824325w in the presence of Cy.

Figure 2. The pattern of aleurone spotting conditioned by bz-rcy812215 in the presence of Cy.

Patrick S. Schnable and Peter A. Peterson

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