V.P. Netsvetaev, Department of Plant Genetics
Belgorod Research Institute of Agriculture,
0ktyabrskaya Str., 58 Belgorod, 308001, Russia.
The spontaneous, high lysine mutant L76 has been isolated from cross Robur X Pallidum 331/13 in 1976. This mutant has shrunken endosperm and reduced synthesis of hordein protein fractions, like other high lysine forms (Garkavy et al., l979).
Hordein of L76 and its parents were tested by starch gel electrophoresis at pH 3.1. The results are demonstrated at Fig. 1 and Fig. 2. Hordein was isolated with 70% ethanol (Click here for Fig. 1) and 70% ethanol + 0.01M dithiotreitol (DTT) (Click here for Fig. 2). The DTT lncreases a solubility of B-hordein fraction of barley varieties. There are comparatively low effect of DTT on solubility of a B-hordein of the L76 mutant. Thus, the L76 has reduced synthesis of fast-moving hordeins, unlike to its parents, and a new component - y is observed. The lntensity of L76 component - x is reduced very much (Fig. 1, 2). Perhaps, the parent's component - X is more complex. Changing of an x-component lntensity of L76 mutant could be explained by changing one of genes that results the synthesis of an X-hordein complex as well.
Studying of hordein inheritance in crosses with L76 shows, that fast-moving components intensity of L76 type on electrophoregramms of heterozygous seeds does not increase. Intensity of hordein bands of normal parents has been correlated with dosage gene effect of Hrd -alleles in heterozygous seeds.
The analysis of F2 population of L76 X Odesskiy 46 (n-360) has showed, that reduced synthesis of the fast-moving hordeins and B-hordein of the L76 type are caused by a single gene (or closely linked genes). Perhaps, L76 mutation has tought regulation and structure parts of locus Hrd B.
The inheritance of shrunken endosperm in cross L76 X 0desskiy 46 shows, that this character is controled by a single dominant factor, designated here as Sex76. A heterozygous plant gives us two clearly distinguishing classes of seeds - shrunken and normal one (Table 1). The shrunken seeds expression was various among different seeds from heterozygous plant. Maybe assumed that development degree of endosperm depends on Sex gene dose in
triploid endosperm of grain. If shrunken seeds of heterozygous plants have significantly higher seed weight in comparison with seeds of homozygous plants SexSex, consequently our supposition about the dose effect of gene Sex will be quite right. The kernel weight of SexSexSex seeds is 38.8 +/- 0.37 mg and the kernel weight of shrunken seeds from heterozygous plants (SexSexSex + SexSexsex + Sexsexsex) is 42.06 +/- 0.57 mg. Differences between these two groups of samples estimated on criteria t were significant at LSD-1% (t-5.12). Hence, gene Sex76 is inherited as semidominance gene and it could included in group of the Sex genes.
Table 1. Inheritance of the Sex76-gene and its relation to kernel weight.
| Plant genotype | No. of plants tested | Endosperm genotype | weight (mg) | Ratio of endosperm genotypes | |
|---|---|---|---|---|---|
| Sex - -: sex sex sex | |||||
| observed | theoretically | ||||
| X2=0.29 | (3 : 1) | ||||
| sex sex | 20 | sex sex sex | 49.45+/-0.66 | - | - |
| Sex Sex | 21 | Sex Sex Sex | 38.82+/-0.37 | - | - |
| Sex sex | 16 | Sex - - | 42.06+/-0.57 | 2692 | 2706 |
| sex sex sex | 50.16+/-1.23 | 916 | 902 | ||
The studing of the Sex76 gene linkage with hordein encoding by loci Hrd A and Hrd B, which are located in a short arm of chromosome 5 (Netsvetaev and Sozinov, 1982), are made in F2 of cross L76 X Odesskiy 46 (test of seeds F3). L76 has alleles Hrd A2 Hrd B30 Hrd F2 Sex76, and Odesskiy 46 has - Hrd A3 Hrd B6 Hrd F4 sex76. The locus Hrd F was not identified. Results are summarized in Table 2.
Thus, gene Sex76 is located in short arm of chromosome 5 near (or on) locus Hrd B.
Table 2. Estimation of linkage Sex76 with loci Hrd A and Hrd B.
| Symbols | Phenotype classes of F2 | X2 | Recombination value | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| X | x | Y | y | xxYY | XxYY | XXYY | xxYy | XxYy | XXYy | xxyy | Xxyy | XXyy | % | |
| Sex76 | sex76 | HrdA3 | HrdA2 | 55 | 18 | 3 | 24 | 162 | 21 | 1 | 19 | 57 | 236.3 | 13.59 +/- 1.39 |
| Sex76 | sex76 | HrdB6 | HrdB30 | 78 | 3 | 0 | 2 | 195 | 0 | 0 | 1 | 81 | 617.6 | 0.84 +/- 0.34 |
| HrdA3 | HrdA2 | HrdB6 | HrdB30 | 1 | 26 | 54 | 18 | 160 | 19 | 58 | 21 | 3 | 236.8 | 13.91 +/- 1.41 |
References:
Garkavy, P.F., A.M. Sheremet, V.P. Netsvetaev, A.A. Pomortsev. 1979. Spontaneous high lysine mutant of winter barley L76. (In Russian). Doklady VASKhNIL, No.12, pp.:3-5.
Netsvetaev, V.P. and A.A. Sozinov. 1982. Linkage studies of genes Gle 1 and Hrd F in barley chromosome 5. BGN 12:13-18.
