BORRINO, E. M., and POWELL, W. 1988. Stomatal guard cell length as an indictor of ploidy in microspore-derived plants of barley. Genome, 30: 158 -160. A cytological examination of 96 microspore-derived barley genotypes indicated that haploid and diploid progeny were produced in approximately equal proportions. In order to discriminate between haploid and nonhaploid derivatives, indirect ploidy evaluation techniques were examined. Stomatal guard cell length provided a'convenient and reliable method for classifying microspore-derived plants into haploid, diploid, and tetraploid groups.

From an F1 hybrid between the two barley (Hordeum vulgare L.) cultivars 'Golden Promise' and 'Mazurka' a series of doubled haploid (DH) lines were generated both from microspores by anther culture and from immature zygotic embryos after hybridization withH. bulbosum. The DH lines from both sources were used to monitor the segregation of the five major genes, rachilla hair length, DDT susceptibility, height, C hordein polymorphism and mildew resistance. Whereas the microspore-derived samples showed significant departures from the expected 1∶1 ratio for three of the five genes, theH. bulbosum lines showed deviation for only one gene. Analysis of linkage data also showed differences between the two series of DH lines. Cytogenetic analysis revealed a mean chiasma frequency in theH. bulbosum lines which was very similar to the F1 hybrid. In contrast, four of the ten microspore derived lines examined showed a reduced chiasma frequency. One showed evidence of translocation heterozygosity.

This report describes a study of androgenesis in Dactylis glomerata, where the main aim was to find anther culture-responsive clones. Two types of media and two sugars were compared for their effectiveness in anther culture induction and subsequent plantlet production.Embryo formation from the cultured anthers was obtained from 28 of the 108 cloned genotypes using two different substrates, R2M and FW. Both induction media supported the formation of embryos from the cultured anthers, but around 4.5 times more embryos (0.81 embryos per 100 anthers) were obtained with R2M compared with FW, and R2M also gave 5.5 times more green plants (0.054 green plants per 100 anthers) than the FW substrate.In the investigation of a carbohydrate source, responsive clones from the genotype study were tested using maltose as a substitute for sucrose in R2M. Using maltose instead of sucrose increased embryo formation so that 133 embryos per 100 anthers were obtained compared with 7.1 embryos per 100 anthers obtained with sucrose. The total number of green plants obtained was also improved with maltose compared with sucrose, resulting in 66.3 and 1.9 green plants per 100 cultured anthers, respectively.Dactylis glomerata L. (2n = 4x = 28) is a natural tetraploid and a highly allogamous grass with an effective incompatibility system. It is one of the most widely distributed grasses in the world and contains considerable genetic variation (Borrill 1978, Lumaret 1988). Breeding of the species is complicated by the high degree of heterozygosity and its tetraploid nature, which leads to very heterogeneous populations and limited progress from selection. Reduction of tetraploid D. glomerata to the diploid level would enable more efficient selection for agronomically important traits because of the simpler diploid genetic segregation. In addition, subsequent chromosome doubling of diploids should lead to increased homozygosity and thus increased uniformity of subsequent tetraploid lines, which will improve the accuracy of measurements of combining ability and breeding value.Results of anther culture with orchard grass have been reported by Saito et al. (1973), who obtained two calli from D. glomerata anther culture, one of which regenerated to give an albino plant. Songstad and Conger (1988), working with anther culture in D. glomerata, obtained about 13 000 somatic embryos, of which one might have been of gametic origin.This paper reports the successful induction of diploid, tetraploid, and octoploid regenerants from D. glomerata anther culture. Materials and MethodsThe plant material for the genotype study consisted of 14-16 individual plants from each of 18 autotetraploid {In = 4JC = 28) varieties and breeding populations of orchard grass (Z). glomerata L.). In total, 264 plants were provided by DLF-Trifolium A/S, Denmark. Plants were cloned and represented by one ramet in each of two environments. After vernalization for 4 months at 3-5°C, the plants were grown to flowering under glasshouse conditions. Plants in the first environment were...

A preliminary study of the effects of pollen irradiation on the cytology of subsequent generations has been conducted on crosses within three crop groups: brassica, barley and potatoes. The hybrid chromosome complement of progeny from an interspecific cross in brassica supports previous observations (in Nicotiana and wheat) of a conventional fertilisation event following poilen irradiation. Cytological examination of Ml mitosis in brassica and potatoes revealed the frequent occurrence of aneuploidy and structural rearrangements. However, aneuploidy was not found in barley and the structural re-arrangements detected were less frequent and less extensive than reported in other species. Mitosis and meiosis of Ml and M2 generations of barley were screened for aberrations. Fertility of the Ml was reduced but was restored in the M2 of plants which were not carrying a translocation.

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