University of Pennsylvania

Genetic maps of visible and RFLP markers in the vicinity of Tp1 and Tp2
--Deverie Bongard-Pierce, Mark Dudley and Scott Poethig

Restriction fragment length polymorphism (RFLP) maps of the regions around teopod1 (tp1) and teopod2 (tp2) were constructed using probes obtained from the University of Missouri (umc), Brookhaven National Laboratories (bnl), Native Plants Incorporated (npi) and Pioneer Hi-Bred Intl. (php). RFLPs in the vicinity of Tp1 were mapped in the following testcross: Gl1 Tp1 Sl/gl1 tp1 sl x gl1 tp1 sl. gl1 and sl are the most tightly linked mutations flanking Tp1. 254 progeny from three related families were scored for recombination between these loci and 55 individuals that were recombinant for the visible markers were subjected to RFLP analysis. These recombinants provide the following map: gl1--8.7--umc116--3.9--php20569--0.8--Tp1--1.6--bnl15.21--6.3--php15037--0.4--sl. These data confirm previous results (R.S. Poethig, MNL63:101) concerning the order of gl1, Tp1 and sl but provide a significantly different value for the distance between Tp1 and sl. In each of the three related families, Tp1 and sl exhibited approximately 8% recombination; by contrast, in previous experiments these genes were separated by 3% recombination. It should be noted that our data place bnl15.21 and umc116 in an inverted position relative to php20569 compared to the positions of these loci in the most recent maps from the Brookhaven Lab and Pioneer Hi-bred. However, the distances we observed are comparable to those measured by these two groups.

RFLPs in the vicinity of Tp2 were mapped using the test cross: -- Tp2 R-r /Ds tp2 R-scm; C/C x P-VV; r;c. 40 recombinants between Ds and R- were observed in 290 individuals. All of these recombinant plants as well as 65 non-recombinant plants were scored for the segregation of RFLPs in this region. Two RFLPs, php20719 and umc163, exhibited no recombination with Tp2 in this cross. In order to map these probes, 615 progeny from the cross Tp2 G/tp2 g x tp2 g were scored for recombination between Tp2 and G and the resulting 12 recombinants were subjected to RFLP analysis. This cross allowed php20719 to be positioned 0.8cM distal to Tp2. Because none of the Tp2--g recombinants were recombinant for umc163, the position of this marker is still in doubt. Our current map of the region around Tp2 is as follows: php15013--11.8--umc155--5.7--npi264--1.9--Ds
--1.4--(Tp2, umc163)--0.8--php20719--1.1--g--11--umc44a--1.4--R

Please Note: Notes submitted to the Maize Genetics Cooperation Newsletter may be cited only with consent of the authors

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