Maize
Genetics Cooperation Newsletter 80. 2006.
In 2004 (MNL 78:63-64), we reported the results of linkage tests of the mutable r1 haplotype-specific enhancers of aleurone color Fcu and arv‑m594 with respect to wx1 in a set of wx1 marked reciprocal translocations. Tightest linkage with wx1 was obtained for both factors with the translocation wx1 T2‑9d (breakpoints 2L.83; 9L.27). Since then, linkage data with respect to the chromosome 2 markers fl1, v4, w3, and Ch1 have further refined the position of Fcu on 2L (Stinard; this MNL), and the factors Fcu, arv‑m594, arv‑m694, Arv‑V628#16038, and Fcu‑R2003‑2653‑6 have been found to map to the same position (Stinard; this MNL). In parallel, linkage crosses of arv‑m694, Fcu‑R2003‑2653‑6, and Arv‑V628#16038 were performed with wx1 T2‑9d, and the results are reported below.
Linkage crosses were set up as indicated in Tables 1 (arv‑m694), 2 (Fcu‑R2003‑2653‑6), and 3 (Arv‑V628#16038). Lines homozygous for enhancers were crossed to wx1 T2‑9d, and the resulting F1�s were outcrossed as males to tester lines homozygous for wx1 and the reporter haplotype R1‑r(Venezuela559‑ PI302355). Kernels from the test cross ears were scored for waxy (wx) vs. starchy (Wx) endosperm and sectored (arv‑m) or full-colored (Fcu‑R or Arv) vs. stable pale (arv or fcu) aleurone. The results and linkage values are reported in Tables 1, 2, and 3.
Table 1. Two point linkage data for wx1 and arv‑m694 in crosses involving T2‑9d. Data from four ears.
Testcross: wx1 N arv R1‑r(Venezuela559‑PI302355) X [wx1 T arv r1 X Wx1 N arv‑m694 R1‑r(Venezuela694#16037)]
|
Region |
Phenotype |
No. |
Totals |
|
|
|
|
|
|
0 |
Wx arv‑m |
265 |
|
|
|
wx arv |
228 |
493 |
|
|
|
|
|
|
1 |
wx arv‑m |
49 |
|
|
|
Wx arv |
45 |
94 |
|
|
|
|
|
|
n |
|
|
587 |
Map distance wx1 – arv‑m694 = 16.0 � 1.5 cM
Table 2. Two point linkage data for wx1 and Fcu‑R2003‑2653‑6 in crosses involving T2‑9d. Data from three ears.
Testcross: wx1 N fcu R1‑r(Venezuela559‑PI302355) X [wx1 T fcu r1 X Wx1 N Fcu‑R2003‑2653‑6
R1‑r(Venezuela559‑PI302355)]
|
Region |
Phenotype |
No. |
Totals |
|
|
|
|
|
|
0 |
Wx Fcu‑R |
153 |
|
|
|
wx fcu |
155 |
308 |
|
|
|
|
|
|
1 |
wx Fcu‑R |
15 |
|
|
|
Wx fcu |
25 |
40 |
|
|
|
|
|
|
n |
|
|
348 |
Map distance wx1 – Fcu‑R2003‑2653‑6 = 11.5 � 1.7 cM
Table 3. Two point linkage data for wx1 and Arv‑V628#16038 in crosses involving T2‑9d. Data from six ears.
Testcross: wx1 N arv R1‑r(Venezuela559‑PI302355) X [wx1 T arv r1 X Wx1 N Arv‑V628#16038
r1‑g (Stadler)]
|
Region |
Phenotype |
No. |
Totals |
|
|
|
|
|
|
0 |
Wx Arv |
356 |
|
|
|
wx arv |
360 |
716 |
|
|
|
|
|
|
1 |
wx Arv |
47 |
|
|
|
Wx arv |
79 |
126 |
|
|
|
|
|
|
n |
|
|
842 |
Map distance wx1 – Arv‑V628#16038 = 15.0 � 1.2 cM
All
three enhancers showed linkage with wx1
in crosses involving T2‑9d, although the map distances varied
somewhat. The values with respect
to arv‑m694 (16.0 � 1.5
cM), Fcu‑R2003‑ 2653‑6 (11.5 � 1.7 cM), and Arv‑V628#16038 (15.0 � 1.2 cM) maybe be directly compared with
those previously reported for Fcu
(13.6 � 0.9 cM) and arv‑m594
(9.4 � 0.8 cM; MNL 78:63-64). All
five factors show little if any recombination with each other (Stinard, this
MNL). However, discrepancies
between linkage values with respect to wx1 marked translocations are not unusual (EB Patterson, Ph.D.
Dissertation, 1952) and could be due to differences in genetic background or
environmental factors.
_________________________________________________
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note:
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