Ac11 acts early in plant development

--R. Kelly Dawe and Michael Freeling

The Ac (Ac11) element in the stock that gave rise to Adh1-2F11 was found to induce large leaf and tassel sectors in plants expressing bz2-m, a1-m3 and a1-m4 (Dawe and Freeling, 1990, Dev. Biol. 142:233-245). About 15% of plants with Ac11 (and an appropriate Ds reporter allele) have sectors as large as one half tassel branch, and sectors are often larger than half of the tassel circumference. Ac11 has a similar effect on Ds elements that cause chromosome breakage (Scott Poethig, personal communication).

Ac11 was mapped 18 units distal to wx on chromosome 9 (and 2 units from bz1). The Ac element in the stock that gave rise to Adh1-Fm335 (Ac335) was found to induce late plant sectors and to map 29 units from wx (three point crosses have not been made). Both of these stocks originally came from Drew Schwartz, so these Ac elements are presumably related by a transposition event(s). The difference in the timing of Ac activity is tissue specific. Though more research is needed, Ac11 appears to act later in seed development than Ac335, the reverse of the situation in plant tissues.

Unfortunately Ac11 is not at a known locus, and probably transposes to new sites at a high frequency where it may or may not retain its property of earliness. Nevertheless, as long as the element is maintained in stock where its activity can be monitored, it should prove useful in genetic mosaic studies where Ds is used to remove a wild type allele by chromosome breakage (Neuffer, MNL 63:61). Whether or not the earliness of Ac11 affects the overall transposition frequency has not been investigated.

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