tnpR - one form can be En; is this a possible reverse dosage

--Peter A. Peterson

tnpR is an En-related product that reduces the excision frequency of autonomously functioning alleles such as wx-844 (Cuypers et al.) or a-m(Au). Cuypers et al. identified the a-m(r) allele with a 1.8 kb transcript that reduces excision frequency. The phenotype of a-m(Au)/a-m1 sh2 equals a low near colorless kernel with low frequency (2b) spots. This indicates that an En was suppressing the a-m1 expression. When selfed many of the sh2 kernels were colorless with spots. When backcrossed to the a sh2 tester, a-m(Au) reappears. Taken together, this would indicate that an En could act as tnpR or that a functioning, though modified, En could act as tnpR.

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