A Database for Triticeae and Avena
II. 8. Hybrid growth retardation due to two dominant complementary
genes in barley.
T. Fukuyama, The Ohara Institute for Agricultural Biology, Okayama University,
In the course of studies on interaction between the nucleus genes of
H. vulgare and the cytoplasm of H. bulbosum, a specific F1
hybrid was found to exhibit a marked growth retardation as compared with
many other F1's. The process of finding this event and result of genetic
study are given below:
In 1977, a Japanese two-rowed cultivar, Shin Ebisu 16(SE 16) was crossed
to a Turkey six-rowed one, T. 193. The resultant F1 plant was grown in
the field next year, and records were taken for date of heading, number
of tillers, culm and ear length, and number of triplets per spike. As apparent
in Table 1, the F1 was markedly less in number of tillers than their parents.
Moreover, it was intermediate between parents for lengths of culm and ear,
although an F1 hybrid is well-known to exhibit heterosis and is generally
longer in stem length than their parents. No difference was observed in
date of heading and number of triplets between F1 and SE 16.
Table 1. Date of heading, number of tillers, lengths
of culm and ear, and number of triplets in F1 plants obtained from vulgare
(V) and bulbosum (B)-cytoplasmic SE 16 x T. 193 and their parents.
Along with the above experiment, a cross between an alloplasmic SE 16
with cytoplasm of H. bulbosum and T. 193 was made, and characters
of the resultant F1 of (B)-F1 were compared with those of autoplasmic F1
[(V)-F1] stated above. As seen also in Table 1, (B)-F1 headed much later
than and was markedly inferior to (V)-F1 as to number of tillers, lengths
of culm and ear, and number of triplets. The result shows that the growth
retardation of the hybrid is intensified by the interaction with the deleterious
effects of bulbosum cytoplasm.
Next, the seeds, taken from auto- and allo-plasmic F1, were planted,
and number of tillers and culm length of each of the F2 plants were measured.
Fig. 1 shows frequency distribution of growth-indices estimated by use
of discriminant function based on number of tillers and culm length. A
clearcut bimodal distribution in both auto- and allo-plasmic groups indicates
that they are classified into normal and retardant types. And a number
of these two phenotypes thus classified were found to fit well to the calculated
ones on a 9:7 segregation ratio (Table 2). It may be safe to conclude that
the growth retardation expressed by the hybrid of SE 16 x T. 193 is controlled
by two dominant complementary genes, which are tentatively designated as
GrtS involved in SE 16 and GrtT in
T. 193. It was also known that these two genes were independently inherited
with Vv for six-rowed character.
Table 2. F2 segregation of growth type, retardant
or normal one, in the cross of vulgare (V)- and bulbosum
(B)-cytoplasmic SE 16 x T. 193.
Figure 1. Observed frequency distribution for growth-indices
calculated from discriminant functions for number of tillers and culm length
in auto- (a) and allo-plasmic (b) F2.
BGN 10 toc
BGN Main Index