Genetic control of recombination in barley: III ... - Wiley Online Library

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northern Europe, LINDE-LAURSEN et al. (1982) found 8 alleles at Hor 1 and 12 alleles .... I am most thankful to Dr. Hans Doll and. Mrs. Bente Andersen, Rim for ...
Hereditas 115: 13--16 (1991)

Genetic control of recombination in barley 111. Recombination between the hordein loci in three different genotypes TORBJORN

SALL

Department of Crop Genetics and Breeding, Swedish University of Agricultural Sciences, Svalov, Sweden

SALL, T. 1991. Genetic control of recombination in barley. 111. Recombination between the hordein loci in three different genotypes. - Hereditas 115: 13-16. Lund, Sweden. ISSN 0018-0661. Received May 8, 1991. Accepted May 13, 1991 The recombination frequencies between the Hor 1 and Hor 2 loci on the short arm of the chromosome 5 were investigated in three different barley crosses. The mother lines were the three barley varieties Aha, Laevigatum and Isaria. while N1501 was used as the father line in all cases. The recombination frequencies between the hordein loci were 11.1%, 11.9%, and 14.9% for the Aha, Laevigatum, and Isaria crosses respectively. The rank order between the crosses with respect to the recombination frequencies coincides with the results earlier obtained on recombination on chromosome I . A one-tailed statistical test showed that the differences are significant. Torbjorn Sall, Department of Genetics, Uniuersity of Lund, Solvegalan 29, S-223 62 Lund, Sweden

There are two different aspects of the genetic con- from these two loci several other minor loci exist. trol of recombination, namely the control of the For more information on the hordeins in general, total amount of recombination in the genome and see KREISet al. (1987). The two loci, Hor 1 and Hor 2, are highly the control of the distribution of recombination over the chromosomes ( SIMCHENand STAMBERGpolymorphic. In a study of 51 accessions of the 1969). Thus, when variation for recombination wild progenitor of cultivated barley, Hordeum vulbehaviour is found, it is of interest to consider gave spontaneum, DOLLand BROWN(1979) found which of these aspects are involved in causing the 33 different alleles for the Hor 1 locus and 38 different alleles for the Hor 2 locus. In a study of variation. In earlier studies of spontaneous variation in 59 varieties of two-row cultivated barley from recombination in cultivated barley, we have shown northern Europe, LINDE-LAURSENet al. (1982) the existence of such variation for the short arm of found 8 alleles at Hor 1 and 12 alleles at Hor 2. The frequency of recombination between Hor 1 chromosome 1. The experiments focused primarily on a specific region on the arm (SALL et al. 1990; and Hor 2 varies among investigations from 6.3 % (SOZINOWet al. 1979, cited in JENSENet al. 1980) SALL 1990). However, the results from a cytological study of inversion heterozygotes indicated that to 20.5% (SHEWRYet al. 1988). These differences the whole chromosome arm was simultaneously could indicate a genetic variation for recombination, but since the experiments have been made on affected (SWLL et al. 1990). In the present experiment these studies are con- different occasions and with different material no tinued by an investigation of a different chromo- definite conclusions can be drawn from them. The three varieties Aha, Laevigatum, and Isaria some in order to see if the previously observed recombination effect is local or whether it also all contain alleles at the Hor 1 and Hor 2 loci that affects other parts of the genome. For this purpose differ from those found in the inversion line NI501. I have chosen to use the hordein loci on the short It was thus possible to estimate the degree of recombination between the hordein loci on chromoarm of chromosome 5. Hordeins are the major storage proteins in bar- some 5 in material from the same crosses that were ley and represent about half of the total protein used in one of the earlier experiments where the content of a barley seed (SHEWRY et al. 1978). The inversion in N1501 was used to measure recombinamajor part of the hordeins are coded for by two tion in the different combinations (see SALL et al. loci, Hor 1 and Hor 2. These loci have been 1990). There the lines Alva and Laevigatum showed mapped to the short arm of chromosome 5 (SO- a clearly lower recombination frequency than Isaria LARI and FAVRET 1971; ORAMet al. 1975). Apart for the studied region on chromosome 1.

Material and methods

Results

In the present experiment, the Fz seeds obtained lrom selfed F , plants from crosscs bctwcen the inversion line N1501 and the three barley varieties Alva. Ackermanns Isaria ( Isaria) and Hordeim7 disticu/~7 luerigutuin (Laevigatum) were investigated with respect to their recombination frequency between the hordein loci. N1501 is a line carrying a paracentric inversion on chromosome I induced in the variety Foma. For more information about these lines. see SALL et al. (1990) and LINDE-LAURSEN et al. (1982). The alleles found at the Hor I and Hor 2 loci are shown in Table I . The Pr allele at the Hor I locus is dominant to the Fo allele; all other allelic combinations are codoininant. F , plants from these crosses were grown out of doors in a benchyard during the summer of 1984 at the same place and time as the material described in SALL et al. (1990). The plants were harvested at full maturity and seeds were collected for hordein analysis. Extraction and SDS-page electrophoresis of hordeins were carried out according to DOLLand ANDERSEN( 1981). Seeds were crushed and the proteins extracted by propanol. The proteins were then reduced by Dithiotreitol ( DTT), alkylated by Iodine acetic amide (JAA) and precipitated in water. The samples were then dissolved in propanol with Bromphenol blue and run through a 4.50.5 ‘Xi acrylamide-his separation gel. The gels were stained with coomassie brilliant blue.

The observed numbers of each of the possible phenotypes are shown in Tables 2 and 3. I n total, 1783 seeds were investigated, with 678 from the Alva combination. 674 from the lsaria combination and 431 from the Laevigatum combination, A larger number of seeds was investigated in the A h a and lsaria combinations in order to produce similar accuracy in the recombination frequency estimates as obtained in the more informative cross with Laevigatum. The one-locus segregation ratios and the chi-square tests of the Mendelian segregations are shown in Table 4. I t is seen that the effects are nonsignificant with the exception of the Hor 1 locus in the Laevigatum cross, which is just significantly deviant from the expected 1.2: I ratio. The recombination frequencies were estimated by maximum likelihood estimates. The recombination frequencies and their standard errors are shown in Table 5. Alva had the lowest recombination frequency with 0.1 I , Laevigatum showed a slightly higher recombination frequency, 0.12. and lsaria had the highest recombination frequency, 0.15. The estimated recombination frequencies were used to fit the data to a model assuming that the loci were linked but showed Mendelian segregation at each locus separately. The model was tested by a chi-square test. The results are shown in Table 5. I t is seen that all three combinations show a good fit to the model. Because of this good fit. no adjustment for skewed segregations were made. A one-tailed statistical test (assuming approximate normal distribution) showed that the

Tdde 1. Allele.; this experiment

.it

the Hor / and H , J2~ loci in the lines used

111

7”ihlr 3. T h e observed nuniber of each posible phenotype in the Lnevigatuiii combination out 0 1 43 I seeds investigated

Iiivestigated line Hor /

~

Locus

Alva

lsaria

Laevigatum

N1501

tlor I

Pr Rt

Pr Rl

111

Fo

Ri’

Ah

Hor 2

Hw 2

T d h , 2. The number of observations l o r e x h possible phenotype Comhiniirion

DiF.o

For0

66 72 I

26 190 24

20 XI

the Alva and Isaria combinations

Phenotypes Pr-

RtRl Alva luaria

111

RIUI RI‘Ah AhAh

DiDi

I74 I77

PrRlAh

PrAhAh

FoI-0 RIUI

FoFo KlRf

3nx

40 44

3 5

25

304

38

I-OF0

AhAh

Totd

I18 I Oh

678 674

I

Herediras 115 (1991)

GENETIC CONTROL OF RECOMBINATION IN BARLEY 111

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Table 4. One-factor segregations and tests to the Mendelian expectation Investigated line

Aha

Isaria

Laevigatum

Locus Hor 2

Locus Hor f Phen.

Oh$.

y2

df

p

Phen.

Obs.

y2

df

p

PrFoFo

522 126

1.4

1

0.23

RfRf RfAh AhAh

177 333 168

0.45

2

0.80

PrFoFo

525 149

0.08

RfRf RfAh AhAh

182 342 150

3.2

2

0.19

DiDi DiFo FoFo

89 240 102

RfRf RfAh AhAh

93 232 106

3.3

2

0.19

I

3.0

6.4

0.04

2

Table 5. Recombination frequencies ( istandard error) and the results of the chi-square tests of a model that assumes Mendelian segregation at each locus and the estimated recombination frequency between them Investigated line

Recombination frequency (%)

x2

df

p

Aha Laevigatum Isaria

1 1 . 1 k 1.3 1 1.9 1.2 14.9 k 1.5

3.7 1.4 4.4

4

0.46 0.39 0.35

I 4

recombination values in the Alva and Laevigatum combinations were significantly lower than in the Isaria combination ( z = 1.83, p < 0.05).

Discussion SIMCHENand STAMBERG(1969) proposed that gradual variation of recombination (as opposed to all or none variation) is specific for genomic regions, i.e., that the frequency of recombination in a particular chromosomal region is influenced by factors closely linked to the region. This suggestion has been carefully investigated in a number of species and found to be untenable. Thus, in a study of the recombination pattern in chromosomes extracted from wild popdations of Drosophila rnelanogaster, BROOKSand MARKS(1986) found differences in both the amount and the distribution of recombination for different regions on the sampled chromosome. In particular, they observed that the different sampled second chromosomes had a direct influence on the recombination pattern on the X chromosome and the third chromosome. A similar result has been reported from Neurospora crassa, where CEDERBERG (1985) found that lines that had been selected for high and low recombination frequencies

for a specific region, also differed with respect to other regions, while yet others remained unaffected. Thus, it is clear that the control of recombination rates is very complex. In the present investigation a similar pattern for recombination frequencies was found on a segment on chromosome 5 compared to what earlier had been observed for chromosome 1 (SALLet al. 1990). These results can be interpreted in two ways. The first is that the whole genome in the investigated lines are under a common control which reduces recombination generally in Alva and Laevigatum relative to Isaria and other lines. The other interpretation is that chromosome 1 and chromosome 5 are controlled by different factors and the fact that both Alva and Laevigatum show low recombination frequencies on both investigated chromosomal regions is merely a coincidence. If the assumption of a common control is true, it seems remarkable that when the markers on chromosome 1 were chosen to measure recombination ( S A L L et al. 1990) it so happened that these were situated on the same arm (out of fourteen possible) where the controlling factors for the whole genome is situated. There is, however, nothing that disproves this hypothesis. It is assumed that the factor controlling recombination on chromosome 1 has been transferred to Alva from Laevigatum (SALL et al. 1990). If there are different factors influencing recombination on chromosome 5 it can not be inferred whether A h a got the factor from Laevigatum or from any of its other progenitor since they were not included in the experiment. Only further inheritance tests will tell. Acknowledgements. - I am most thankful to Dr. Hans Doll and Mrs. Bente Andersen, Rim for teaching me the electrophoresis techniques, and to 0. E. och Edla Johanssons vetenskapliga stiftelse, for supporting my stay at Rise. I would also like to thank the staff at my department for all the help in the lab. I am

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Herrdirns I I5 (1991)

P. R. 1987. Structure and regulation of expression of seed protein genes in barley. - Plant Physiol. Biuchem. 25: 291 -302 LINDE-LAURSEN,1.. DOLL,H. and NIBLSEN, G. 1982. Giemsa patterns and some biochemical markers in a pedigree of European barley. Pfunzenzucht. 88: 191--219 ORAM.R. N., DOLL,H. and KQIE, B. 1975. Genetics of two storage protein variants in barley. Hereditas 8 0 53-58 SALL, T. 1990. Genetic control of recombination in barley 11. Variation in linkage between marker genes. - Heredifas 112: References 171-178 BROOKS, L. D. and MARKS,W. R. 1986. The organisation of SALL,T.. FLINK.J . and BENGTSSON, B. 0. 1990. Genetic control genetic variation for recombination in Drosuphilu melonoof recombination in barley. I. Genetic variation in recombination frequency measured by inversion heterozygotes. - Heredifaster. Genetics 114: 525 541 ias 112: 157.170 CEDERBERG, H. 1985. Recombination in other chromosomal regions than the interval subjected to selection, in lines of SHBWRY, P. R., HILL, J. M., PRATT.H. M., LEGATT,M. M. and Neurosporu crassa selected for high and for low recombination MIFLIN,B. J. 1978. An evaluation of techniques for the extracHerediras 103: 89-97 frequency. tion of hordein and glutelin from barley seed and a comparison B. 1981. Preparation of barley storage DOLL.H. and ANDERSEN, of the protein composition of Bomi and Rise 1508. - J . Exp. Bat. 29: 677-692 protein, hordein, for analytical sodium dodecyl sulphate-polyA n d . Biodwrn. 115: 61 -66 acrylamid electrophoresis. SHEWRY, P. R., PARMAR, s., FRANKLIN, J. and WHITE, R. 1988. DOLL. H. and BROWN.A. H. D. 1979. Hordein variation in wild Mapping and biochemical analysis of Hor 4 (hrdG), a second (Hordeurn spontaneum) and cultivated ( H . uugare) barley. locus encoding B hordein seed proteins in barley (Hordeurn Cun. J . Genet. Cytol. 21: 391 -404 uuIgare L ) Genet. Res. Camb. 51: 5-12 JENSEN, J. H., JQRGENSEN, H. P., JENSFN, H., GIESE,H. and SIMCHEN, G. and STAMBERG, J. 1969. Fine and coarse control of Do1.1. H. 1980. Linkage of the hordein loci Hor 1 and Hor 2 recombination. - Nulure 222: 329%332 with the Powdery Mildew resistance loci MI-k and MI-a on SOLARI,R. M. and FAVRET,E. A. 1971. Polymorphism in Theor. Appl. Genet. 58: 27- 31 barley chromosome 5. endosperm proteins of barley and its genetic control. -- In: KREIS, M., WILLIAMSON. M. S., FORD&, J., CLARKE, J., BUX Barley Genetics II (ed R. NILAN), Washington State University C.. GALLOIS. P. and SHEWRY, Press, p. 23-31 TON,B.. PYWELI.. J., MARRIS,

most thankful to Drs Barbara Giles and Marcy Uyenoyania for helpful comments on the manuscript and correction of the language. This research has been supported by the Swedish Natural Science Research Council and the Swedish Council for Forestry and Agricultural Research, through grants to Bengt 0. Bengtsson.

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