1. In the News Letter of March 23, 1937, pp. 1, 2, it was shown by means of three-point tests involving tho genes sr, P, and br and the translocations T1-5a and T1-5c, that the order of the genes is sr - P - br with the translocation breaks between P and br. Backcross data from 476 individiials were also presented suggesting that ts2 is between P and what was then called T1-10b but now designated T1-2c.

Records of the past summer presented below show that T1-2c is to the left of P very near sr, that ts2 is to the left of P with ms17 presumably to the left of ts2, and that T1-3a and T1-9c are probably to the right of P. The data are as follows:

Genes Phase XY Xy xY xy Total % Recomb.
Sr T1-2c CB 151 1 1 144 297 0.7

 

2.0%
F1 genotype 0 1 2 1, 2 Total
ts2  P   +   76 93 1 2 17 22 0 0  
+   + T1-5b 169 3 39 0 211
    1.4% 13.7%  
 
ms17  P   +   26 25 3 2 15 13 2 1  
+   + T1-5b 51 5 28 3 87
    5.7% 32.2% 3.4%  
 
ts2  P  +    106 140 3 1 29 36 0 0  
+   + T1-3a 246 4 65 0 315
  1.3% 20.6%  
 
ms17  P  +    54 33 2 0 7 5 0 0  
+    + T1-3a 87 2 12 0 101
    11.9%  
 
sr  P  +    38 32 24 17 0 5 0 1  
+  + T1-9c 70 41 9 1 117
    35.0% 4.3% 0.9%  
 
From '37
News Letter		 97 24 5 3 129
167 65 10 4 246
    26.4% 4.1% 1.6%  
 
T1-2c +  P 156 138 51 29 2 1 0 0  
+    ts2 + 294 80 3 0 377
+    ts2 P 204 276 50 49 3 0 0 1  
T1-2c +  + 480 99 3 1 583
  774 179 6 1 960
    18.7% 0.6% 0.1%  
 
From '37
News Letter		 401 70 5 0 476
1175 249 11 1 1436
    17.4% 0.8% 0.1%  
 
+    ms17  P 152 157 29 31 3 5 0 4  
T1-2c +   + 309 60 8 4 381
    15.7% 2.0% 1.0%  

 

Two of the cultures reported above involving T1-2c with B of chromosome 2 and P and ts2 of chromosome 1, gave the following data from

B  T1-2c  +  P
+    +   ts2 +

0 1 2 3 1,2 1,3 2,3 1,2,3 Total
122 111 27 34 30 21 2 0 8 21 1 0 0 0 0 0  
233 61 51 2 29 1 0 0 377
  16.2% 13.5% 0.5% 7.7% 0.3% 0 0  

One of these cultures also segregated lg1 as in F2. Using only lg1 plants, the records for

lg1 B T1-2c +  P
  +  +   +  ts2 + 

are:

0 1 2 3 4 1,2 1,3 2,3 1,2,3 Total
28 15 12 10 0 6 3 1 4 79
  19.0% 15.2% 12.7% - 7.6% 3.8% 1.3% 5.1%  

One of the cultures reported above to show close linkage between T1-2c and sr also involved B of chromosome 2 but no marker other than sr of chromosome 1. The data are:

F1 genotype 0 1 2 1,2 Total
B T1-2c + 63 44 28 9 0 0 0 0  
+   +  sr 107 37 0 0 144
    25.7% 0 0  

Since no crossover between T1-2c and sr appeared in this culture, the orientation of these two markers with respect to the rest of chromosome 1 cannot be told.