II. 7. Further notes on the incompatibility between Hordeum vulgare L. cv. Vada x H. bulbosum L.
R. A. Pickering, Welsh Plant Breeding Station, Plas Gogerddan, Aberystwyth, Dyfed, SY23 3EB, Wales, U.K.
One problem associated with doubled haploid production using the 'bulbosum' technique (Kasha and Kao, 1970) is partial incompatibility between Hordeum vulgare L. cv. Vada x H. bulbosum L. leading to reduced seed setting because of pollen tube inhibition in the stylodium and upper ovary wall transmitting tract (Pickering, 1981). The reaction is known to be controlled by a single dominant gene in Vada (Pickering and Hayes, 1976). Since then several other cultivars, some unrelated to Vada, have been reported as possessing a similar incompatibility with H. bulbosum (Pickering, 1979, 1980; Pickering and Morgan, 1982) but there is no evidence to suggest that a different gene is involved (Pickering and Morgan, 1981).
Four near isogenic lines of Universe (a cultivar derived from a cross between Abed 3371 x Vada) have been produced, two of which are compatible and two incompatible with H. bulbosum (Pickering, 1979; Pickering and Morgan, 1980). Morphological tests and isozyme assays on leaf tissue for 18 enzyme systems and general protein analysis on pollinated and unpollinated stigmas revealed no differences between them. However, as both the compatible lines carried the 7E C-banding pattern from Abed 3371 on chromosome 7, and the incompatible lines the 7D C-banding pattern from Vada (Linde-Laursen et al., 1982), it was thought likely that this chromosome carried the incompatibility gene.
Confirmation was obtained by pollinating a testcross of (Vada x Sultan) F1 x Sultan with H. bulbosum (Sultan is compatible with H. bulbosum). Seed sets were recorded 14-17 days later. There was no detectable linkage between the incompatibility gene and markers on chromosome 2 (Pau/pau), 3 (Est-l locus), or 5 (Hor-2 locus) but the presence of a linkage was established between the incompatibility gene and DDT susceptibility on chromosome 7 with a recombination fraction of 0.112 + 0.032.
Despite high seed setting after crossing Vada with rye (Thomas and Pickering, 1979), the incompatibility between this cultivar and H. bulbosum resembles that of wheat x rye, wheat x H. bulbosum, and barley x wheat in its manifestation, (pollen tube inflation and bursting in the transmitting tract of stylodia and upper ovary wall; see for example Pickering, 1981). Furthermore, barley chromosome 7 and wheat chromosome 5, which both possess incompatibility factors, show some homoeology (Islam and Shepherd, 1981) and provide further evidence of a relationship between these interspecific and intergeneric incompatibility systems.
Nevertheless, although it was thought that an osmotic imbalance between pollen tube and stylodium may be responsible for the inflation and bursting of tube tips (Pickering, 1981), this has yet to be confirmed. For example, there was no effect on seed setting after detaching tillers of incompatible and compatible lines of cv. Universe prior to pollination with H. bulbosum, and placing their cut ends in solutions of polyethyleneglycol. This was carried out to simulate drought stress and influence the internal water potentials of the plants. But in wheat and barley, the female reproductive tissue may be protected from internal fluctuations in water potentials because of the presence of xylem discontinuities at the base of the ovary (Barlow et al., 1980; Kirby and Rymer, 1975; Zee and O'Brien, 1970). However, there was again no effect on seed setting when spikes were immersed in sucrose solutions at various times after pollination.
Attempts to overcome the incompatibility have not been fully effective, but significant increases in seed setting have been obtained after screening and selecting from a range of H. bulbosum genotypes (Pickering, 1980), the best of which are now used in the doubled haploid programme.
Acknowledgments:
I am most grateful to Dr. I. Linde-Laursen, Riso Research Establishment,
Roskilde, Denmark for the C-banding analyses; Dr. P. R. Shewry, Rothamsted
Experimental Station for hordein tests and Dr. T.W.A. Jones and Miss A.
Thomas, Biochemistry Department, Welsh Plant Breeding Station for isozyme
assays.
References:
Barlow, E.W.R., J. W. Lee, R. Munns and M. G. Smart. 1980. Water relations of the developing wheat grain. Aust. J. Plant Physiol. 7:519-525.
Islam, A.K.M.R. and K. W. Shepherd. 1981. Wheat-barley addition lines: their use in genetics and evolutionary studies of barley. In Barley Genetics IV (Proc. IVth Int. Barley Genetics Symp.):729-739.
Kasha, K. J. and K. N. Kao. 1970. High frequency haploid production in barley (Hordeum vulgare L.). Nature 225:874-876.
Kirby, E.J.M. and J. L. Rymer. 1975. The vascular anatomy of the barley spikelet. Ann. Bot. 39:205-211.
Linde-Laursen, I., H. Doll and G. Nielsen. 1982. Giemsa C-banding patterns and some biochemical markers in a pedigree of European barley. Z. Pflanzenzuchtg. 88:191-219.
Pickerings R. A. 1979. Further investigations on partial incompatibility in crosses between Hordeum vulgare L. and H. bulbosum L. Proc. Conf. Broadening Genet. Base Crops; Wageningen 1978:319-325.
Pickering, R. A. 1980. Attempts to overcome partial incompatibility between Hordeum vulgare L. and H. bulbosum L. Euphytica 29:369-377.
Pickering, R. A. 1981. Pollen tube-stylodium interaction in Hordeum vulgare L. x H. bulbosum L. In Barley Genetics IV (Proc. IVth Barley Genetics Symp):666-676.
Pickering, R. A. and J. D. Hayes. 1976. Partial incompatibility in crosses between Hordeum vulgare L. and H. bulbosum L. Euphytica 25:671-678.
Pickering, R. A. and P. W. Morgan. 1980. Rep. Welsh P1. Breed. Stn. for 1979:79-80.
Pickering, R. A. and P. W. Morgan. 1981. Rep. Welsh P1. Breed. Stn. for 1980:70-71.
Pickering, R. A. and P. W. Morgan. 1982. Rep. Welsh P1. Breed. Stn. for 1981:76-78.
Thomas, H. M. and R. A. Pickering. 1979. Barley x rye crosses. The morphology and cytology of the hybrids and the amphidiploids. Z. Pflanzenzuchtg. 82:193-200.
Zee, S. Y. and T. P. O'Brien. 1970. A special type of tracheary element associated with 'xylem discontinuity' in the floral axis of wheat. Aust. J. Biol. Sci. 23:783-791.