66 
PACIFIC SCIENCE, Vol. IX, January, 1955 
When purple flowers are crossed to yellow 
flowers, the purple on yellow background 
results in a purplish red, or bronzy color 
which is easily distinguishable from purple 
appearing on a white background. For con- 
venience, the interaction of purple and yellow 
will be referred to as bronze, and purple on 
white background as purple. The cross be- 
tween purple and yellow resulted in all bronze 
flowers. The F 2 generation segregated out into 
9 bronze, 3 purple, 3 yellow, and 1 white, 
indicating that yellow and purple are inde- 
pendently inherited (Table 3). 
purpleback. It was mentioned earlier that 
the anthocyanin pigment which occurs in the 
outer epidermal layer of the limb extends to 
the back of the tube. It was found that 
parents 2 and 16 bred true for purpleback. 
Parent 8, having a yellow limb with purple- 
back, parent 7, having white limb with pur- 
pleback, and parent 11, having purple limb 
with purpleback, were found to be hetero- 
zygous for this character. 
Parent 16, which is homozygous for purple- 
back, when crossed with yellow, gave all 
purpleback offspring. The F 2 generation of 
this cross together with a few others are given 
in Table 4. The combined ratios of purpleback 
to non-purpleback was 166:56, which fits a 
3:1 ratio. Purpleback, B, exhibits a simple 
dominance to non-purpleback, b. 
Tables 5 and 6 show the dihybrid ratios 
between the factors P and B and Y and B 
respectively. In either case, the ratios obtained 
fit 9:3:3 :1, indicating that B is independently 
inherited from genes P and Y. 
Basic flower color in A. gangetica is gov- 
erned by three sets of genes: P, producing 
TABLE 3 
The Ratio of Bronze ( PY ), Purple (Py), Yellow (pY), and White (py) Flowers Resulting 
from Families Heterozygous for P and Y in Asystasia gangetica 
OBSERVED 
CALCULATED 
PROGENY 
CHI-SQUARE 
Bronze 
Purple 
Yellow 
White 
Bronze 
Purple 
Y ellow 
White 
(PY) 
(Py) 
(PY) 
(py) 
(PY) 
(Py) 
(PY) 
(py) 
( 6 X White) Selfed 
66 
18 
16 
6 
59-625 
19.875 
19.875 
6.625 
1.674 
(12 X Yellow) Selfed 
89 
32 
25 
12 
88.875 
29.625 
29.625 
9-875 
1.369 
Total 
155 
50 
41 
18 
148.5 
49.5 
49.5 
16.5 
2.491 
Chi-square = 7.815 at 5% level. 
TABLE 4 
The Segregating Ratio of Purpleback to Non-Purpleback from Families Heterozygous 
for Purpleback in Asystasia gangetica 
PROGENY 
OBSERVED 
CALCULATED 
CHI-SQUARE 
Purple- 
back 
Non-Purple- 
back 
Purple- 
back 
Non-Purple- 
back 
(16 X 5) Selfed 
70 
24 
70.5 
23.5 
.109 
( 7 X 14) Selfed 
31 
8 
29.25 
9-75 
.419 
(11 X White) Selfed 
17 
7 
18 
6 
.223 
( 7 X 3) Selfed 
48 
17 
48.75 
16.25 
.046 
Total 
166 
56 
166.5 
55.5 
.007 
Chi-square == 3.841 at 5 % level. 
