Data supporting linkages between four loci are given in Table 2.
Mendelian segregations were confirmed for five isozyme loci presumed by Second (1982) and Glaszmann et al. (1984). Assay was done by starch-gel electrophoresis. Loci identified were Amp-1 (aminopeptidase using Leu-NA substrate,=Lap-F), Amp-2 (aminopeptidase using Ala-NA substrate,=Alap-A), Est- cl (esterase, = Est-Ca), Pgd-1 (6 phosphogluconate dehydrogenase, = Pgd-A), and Sdh-1 (shikimate dehydrogenase, = Sdh-A). All the alleles tested were found to be single codominant ones (Table 1). Segregation distortion was observed in some crosses which were between distantly related varieties.
Linkage relationships were examined for 10 isozyme loci including the 5 mentioned above. We found a tight linkage betwen Amp-1 and Est-2 on chromosome 6 (Nishimura's numbering system) as follows:
Table 1. F\2\ segregations for five isozyme loci.
=============================================================================
Locus Cross F\1\ genotype Observed no. of Total x2
A1xA2 A1/A2 F\2\ genotype 1:2:1
A1A1 A1A2 A2A2
=============================================================================
Amp-1 C8669x221 Amp-l2/Amp-11 17 42 23 81 0.93
868xT65 " 25 48 18 91 1.35
Amp-2 868xT65 Amp-22/Amp-21 16 46 29 91 3.73
414xT65 " 18 44 27 89 1.83
C8669x221 " 15 43 24 81 2.17
Est-cl 414xT65 Est-cl2/Est-cl1 34 45 31 110 3.80
868xT65 " 21 43 27 91 1.07
C8669x221 " 32 31 19 81 9.00**
Pgd-1 C8669x221 Pgd-12/Pgd-11 16 40 26 81 2.45
414xT65 " 42 36 8 86 29.16**
868xT65 Pgd-13/Pgd-11 27 43 21 91 2.67
Sdh-1 C8669x221 Sdh1/Sdh2 16 46 19 81 1.98
414xT65 Sdh3/Sdh2 26 40 23 89 1.11
=============================================================================
*,** Significant at 5% and 1% respectively
Data supporting linkages between four loci are given in Table 2.
Table 2. Segregations for Amp-1, Est-2, Pgi-2 and wx loci showing their linkage relations.
=============================================================================
Locus Cross F\1\ genotype Observed no. of Total % X2
combi- A1B1x A1B1 F\2\ genotype recom-
nation A2B2 -------- bination
A2B2 B1B1 B1B2 B2B2
=============================================================================
Est-2 868xT65 Est-21.Amp-12 A1- 25 47 3 1.4
Amp-1 ----------------- +0.8
Est-20.Amp-11 A2A 0 1 15 91 6.74ns
C8669x221 Est-20.Amp-11 A1A1 0 40 22 0.0
----------------
Est-21.Amp-12 A2- 17 2 0 81 2.68ns
=============================================================================
Pgi-2 868xT65 Pgi-22.Amp-12 A1A1 18 7 0 15.2
Amp-1 ----------------- +2.8 5.49ns
Pgi-21.Amp-11 A1A2 4 35 9 91
A2A2 2 2 14
C8669x221 Pgi-22.Amp-11 A1A1 14 6 3 16.2
----------------- +3.0
Pgi-21.Amp-12 A1A2 2 29 2 82 7.31ns
A2A2 1 7 18
=============================================================================
Amp-1 868xT65 Amp-l2.+ A1A1 25a 0 26.5
----------- +3.7 2.05ns
Amp-11.wx A1A2 40a 8 91
A2A2 10a 8
C8669x221 Amp-11.+ A1A1 15a 2 35.2
---------- +5.2 0.98ns
Amp-12.wx A1A2 32a 10 82
A2A2 13a 10
=============================================================================
X2 was calculated for segregation ratio taking an expected recombination
value into account.a Number including B1B1 and B1B2.
References
Glaszmann, J.C., H. Benoit and M. Arnaud, 1984. Classification de riz cultives (Oryza sativa L.): Utilization de la variabilite isoenzymatique. Agr. Trop. 39(1):51-66.
Second, G., 1982. Origin of the genic diversity of cultivated rice (Oryza spp.): Study of the polymorphism scored at 40 isozyme loci. Japan. J. Genet. 57: 25-57.