The rapid production of inbred lines via doubled haploidy by anther culture offers obvious economies of effort in the breeding of new winter barley cultivars. Methods of anther culture have been developed at this Institute in spring barley ( Finnie et al., 1991) and the genetical control of green plant production has been investigated in the winter barley cross Igri * Grit (Andersen et al., 1995). This note concentrates on the application of the methodology to the routine production of breeding lines in a winter barley programme for Scotland.
Scotland is the Northern limit of winter barley production in Europe. A strong local demand for malting barley means that new cultivars must have the best levels of hot water extract to ensure widespread adoption by farmers. Currently only two winter barleys (Halcyon and Sprite) with good malting quality are recommend for growing in Scotland (Scottish Agricultural College, Recommended Cereals 1995). Of these only Sprite can be grown throughout Scotland, Halcyon being restricted to the most southerly growing areas. A series of crosses designed to meet Scottish requirements was produced and subjected to the production of doubled haploids by anther culture. Crosses were made between cultivars such as Manitou, Halcyon, Pastoral, Puffin, Magie and Marinka with a series of inbred lines selected for winter habit from the cross (Doublet * (Atem * Gazelle)) * Torrent. The last parent in this cross has winter habit the others have spring habit and desirable malting characters and disease resistance.
Some thirteen thousand anthers were dissected and plated in culture medium resulting in the production of about 1900 green plantlets (Table 1). There were losses of plantlets, that did not thrive on the regeneration medium, so that it was possible to transplant 1200 plantlets into compost. A further 180 plantlets were lost at transplantation and of the remaining 1059 plants 791 were fertile and produced seed. This latter result might suggest the action of a single gene as the ratio of sterile to fertile plants did not significantly deviate from a 1:3 ratio (Table 2). The genotypes used as the female parents had a marked effect on the number of fertile plants recovered (Fig. 1.).
Table 1. Results of anther culture in the F1 generation from a series of winter barley crosses.
________________________________________________________
Cross Number Number Plantlets Plantlet Number
anthers plantlets per 100 deaths transplanted
cultured anthers
________________________________________________________
9101 1107 164 14.8 35 129
9103 117 20 17.1 8 12
9107 48 1 2.1 1 0
9108 66 1 1.5 1 0
9109 975 208 21.3 69 139
9110 1605 359 22.4 137 222
9111 613 208 5.8 108 100
9112 349 89 25.5 78 11
9113 284 48 16.9 6 42
9115 453 69 15.2 19 50
9116 177 37 20.9 3 34
9117 312 23 7.4 3 20
9123 39 3 7.7 0 3
9124 573 149 26.0 69 80
9127 519 113 21.8 32 81
9128 39 2 5.1 0 2
9129 63 10 15.9 0 10
9131 105 4 3.8 1 3
9132 787 204 25.9 47 157
9134 402 125 31.1 12 113
9135 348 23 6.6 13 10
9142 351 19 5.4 13 6
9147 461 13 2.8 7 6
________________________________________________________
Totals 12877 1893 662 1232
________________________________________________________
Table 2. The production of seed by doubled haploid plant from the F/1/
generation of a number of winter barley crosses following anther
culture.
__________________________________________
Number of plants
Cross ________________
Sterile Fertile Total ChiČ
__________________________________________
9101 27 83 110 0.005
9109 32 90 122 0.037
9110 54 124 178 1.014
9111 16 71 87 0.760
9113 11 30 41 0.027
9115 12 32 44 0.045
9116 5 28 33 0.640
9124 18 48 66 0.068
9127 17 59 76 0.105
9132 31 94 125 0.001
9134 20 71 91 0.166
Totals 243 730 973
__________________________________________
These results suggest that technical improvements are still needed in
several respects of anther culture technology. The overall frequency of green
plant production is still markedly low in view of the potential number of
inducible microspores per anther. An improved protocol for inducing root
formation would have potentially increased the number of plants produced by
50%. While many of the plants that failed to produce grain were haploids, and
thus may have been recovered by colchicine application, a significant number
were not. The latter were not checked cytologically but showed partial
sterility which may have resulted from cytological aberrations. The advantage
in reducing the timescale of inbred line production, two years via doubled
haploids compared to six years by conventional selling systems, means that
further effort to address these problems is justified.
References
Andersen, S. B., Nielsen, B. J., Macaulay, M. M., Waugh, R. and Forster, B.
P.(1995). Randomly amplified polymorphic DNAs (RAPDS) linked to capacity for
grown plant formation in barley anther culture. Theoretical and Applied
Genetics (submitted).
Finnie, S. J., Forster, B. P., Chalmers, K. J., Dyer, A. F., Waugh, R. and Powell, W. (1991). Genetic stability of microspore derived doubled haploids of barley - a cytological, biochemical and molecular study. Genome 34, 923-928.