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X2
test analysis did not fit into the ratios of 5 : 3 and 9 : 7 of
segregating and uniform lines. Although other ratios of 13 : 3 and 3
: 1 could explain the behavior, 3 : 1 model is more acceptable based
on the P value. If all the n umber were pooled together, it still
agrees with this model. The 3 : 1 F2 (F3 lines)
segregating to uniform ratio reported in Table
3 suggests
one pair of recessive genes conditioning uniform and segregation in
this experiment. The probable genetic constitution of HS 131 is
aa conditioning apomixis. The genotype of female is AA.
The F1 hybrid genetic constitution would be Aa,
typical sexual hybrid performance in field as dominant gene A
conditions the sexual reproductive behavior. When selfed, as dominant
gene A either homozygous or heterozygous conditions sexual
reproductive behavior, Mendelian segregation would be expected. On
the contrary, recessive apomictic gene a in homozygous condition
would show uniformity. It yields the progeny of 3 segregating to 1
uniform proportion. According to this, the proposed genetic
composition in F2 generation is shown in Table
4.
In this experiment the facultative apomictic gene demonstrated a
simple inheritance. Also, the uniform lines were present in all
combinations indicating that this trait is genetically controlled and
can be easily manipulated in wheat breeding. This will reduce the
breeding cycle, improve the progeny selection efficiency, improve the
ideal genotype selection frequency, and also put apomixis into
practical use in wheat breeding.
References
Ahokas WW and Bashaw EC (1977) A mutant of barley triploid
inducer. Barley Genet Newsl. 7:4-6.
Bashow EC (1980) Apomixis and its application in crop improvement. In
Hybridization of crop plants. Ed: Fehr WR and Hadl ey HH.
Hybridization of crop plants. ASA and CSSA, Madison :45-36.
Bonnier G and Tedin 0 (1935) The F3 test of homomeric
F2-segregations. Hereditas 21:227-238.
Burson, BL, Voigt PW, Sherman RA and Dewald CL (1990) Apomixis and
sexual in Eastern gamagrass. Crop Sci. 30:86-89.
Burton GW and Jackson JE (1962) Radiation breeding of apomictic
prostrate dallisgrass, Paspalum dilatatum var.
pauciciliantum. Crop Sci. 2:495-497.
Hair JB (1956) Subsexual reproduction in Agropyron. Heredity
10:129- 160.
Hanna WW and Bashaw EC (1974) Apomixis: its identification and use in
plant breeding. Crop Sci. 27:1136-1139.
Voigt PW and Bashaw EC (1974) Facultative apomixis in Eragrotis
curvula. Crop Sci. 10:803-806.
Taliaferro CM and Bashaw EC (1966) Inheritance and control of
obligate apomixis in breeding buffelgrass, Pennisetum ciliary.
Crop Sci. 6: 473-476.
Tinneg M and Aamodt OS (1940) The progeny test as a measure of the
types of seed-development in Poa pratensis. . J Heredity
31:457-464.
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