In an attempt to discover 'A' and 'B' genome donor(s) to finger millet, Eleusine coracana, or its progenitor species, E. africana (both allotetraploid 2n=4x=36), five diploid species, E. Indica, E. Floccifolia, E. multiflora, E. tristachya and E. intermedia, were crossed to finger millet and its progenitor taxon. Crosses were successful only with E. coracana. Three combinations of triploid hybrids E. coracana x E. indica, E. coracana x E. floccifolia, and E. coracana x E. multiflora were obtained and analysed. Meiotic behaviour was perfectly normal in parental species. The regular number of 18 bivalents in E. coracana, 9 bivalents in E. indica, E. intermedia, E. tristachya and E. floccifolia and 8 bivalents in E. multiflora were invariably noticed. In E. coracana x E. indica hybrids a mean chromosome pairing of 8.84I+8.80II+0.03III+0.10IV per cell was found. About 86.5% of the cells showed the typical 9I+9II configuration, suggesting that E. indica (AA) is one of the diploid genome donors to cultivated species E. coracana. A mean chromosome pairing of 11.08I+7.63II+0.16III+0.04IV per cell was found in E. coracana x E. floccifolia hybrids. Two to ten bivalents and varying numbers of univalents were seen in 55% of the cells. About 45% of the cells showed the 9I+9II configuration. Various evidence suggests that perennial E. floccifolia is a primitive member of the 'A' genome group of Eleusine species, and it may not be a genome donor to E. coracana. In E. coracana x E. multiflora hybrids (2n=26) mean chromosome pairing of 21.45I+1.97II+0.13III+0.04IV per cell was found. About 91% of the cells were observed to have 20-26 univalents. Only a small percentage of the cells contained bivalents or multivalents. This pairing behaviour indicates that E. multiflora lacks genomic homology with the 'A' or 'B' genome of E. coracana. Genomically E. multiflora is a distinct species and a genomic symbol of 'C' is assigned to it. Identification of the 'B' genome donor species to cultivated millet. E. coracana remains elusive.

Guizotia abyssinica, G. schimperi and G. scabra are diploid species (2n=2x=30) characterised by 15 bivalents during prophase-I/metaphase-I of meiosis. The former species is cultivated whereas the latter two are wild. Interspecific hybrids between these three species were generated and the F1 hybrids were analysed to assess cytogenetic relationships and crop evolution within the genus Guizotia. Meiotic chromosome configurations at diakenesis/metaphase-I in the pollen mother cells of hybrids averaged 0.25I + 14.60II + 0.15IV for G. abyssinica x G. schimperi, 0.05I + 13.6II + 0.14III + 0.58IV for G. abyssinica x G. scabra, and 0.8I + 12.7II + 0.08III + 0.88IV for G. schimperi x G. scabra. Based upon the results of our investigations we conclude that the genomes of G. abyssinica and G. schimperi are similar and homologous, whereas the G. scabra genome is only partially homologous to that of G. abyssinica/G. schimperi. Furthermore, the crop species G. abyssinica might have originated from G. schimperi through selection and cultivation; chromosome translocations appear to have played a significant role in the divergence and differentiation of these three species.

Two sets of interspecific hybrids E. coracana x E. africana and E. coracana x E. indica were produced. The hybrids were intermediate between the parent species for most of the matrical characters observed. The dominance-recessive relationships of various qualitative characters were studied in the hybrids. Meiotic behaviour was normal in the parent species. Regular 18 bivalents were observed in E. coracana, E. africana and invariably 9 bivalents were noticed in E. indica. In an E. coracana x E. africanahybrid mean chromosome pairing of 0.004 I + 17.71 11 + 0.06 III + 0.08 IV per cell was found. About 87% of the cells showed regular 18 bivalent formation. Preponderance of bivalent formation in the hybrid strongly suggests that the genomes of E. coracana and E. africana are basically similar and E. coracana might have originated as a result of selection and further cultivation of a large grain mutant from E. africana. The genomic notation of AABB has been proposed for these two species. From meiotic analysis it is obvious that E. africana is an allotetraploid and must have originated as a result of hybridization between two diploid taxa followed by chromosome doubling. In triploid E. coracanax E. indica hybrid 99.5 % of the cells contained 27 univalents and 0.5 % of the cells showed a single bivalent and 25 univalents. This pairing behaviour indicates that E. indica may not be A or B genome donor to this millet.

SUMMARY -Eleusine is a small genus currently containing 9 species. From cytological analyses of all nine species it is shown that Eleusine contains three basic chromosome numbers 8, 9 and 10. Among the five diploid taxa the basic number is 8 in E. multiflora (2n = 2x = 16) and 9 in E. floccifolia, E. tristachya, E. indica (all 2n = 2x = 18) and 10 in E. ;aegeri (2n = 2x = 20). The 4 tetraploid species E. africana, E. coracana, E. reniformis (all 2n = 4x = 36) show a base number of 9, while E. compressa (2n = 4x = 40) has a base number of 10. From various lines of evidences it is suggested that 9 is the original base chromosome number in the genus. It appears that aneuploid reduction has played a role in the origin of the number 8 found in E. multiflora, while the two taxa E. ;aegeri (2n = 2x = 20) and E. compressa (2n = 4x = 40) with a x = 10 number appears to have originated through gain to the basic set of nine. In Eleusine the chromosomes are all small to medium in size. The presumed primitive species, E. floccifolia is characterised by a symmetrical karyotype, while the morphologically more advanced taxa show varying degrees of asymmetry in their chromosome complements. Meiotic analysis of the tetraploid taxa shows regular bivalent formation in E. africana, E. coracana, E. reniformis and E. compressa suggesting their allotetraploid origin. There are grounds for arguing that E. coracana originated through selection and further cultivation of a large grain mutant from E. africana, while E. reniformis appears to be a simple varietal derivative of E. coracana.

A single B-chromosome was found (2n = 2x = 30 + lB) in a few Ethiopian populations of G. scabra ssp. scabra out of several natural populations covering the major distribution range. The B chromosome is small and one third the length of smallest A-chromosome and appears to be heterochromatic. In mitotic and meiotic system it shows numerical stability. The B-chromosome do not pair with any member of A-chromosome complement during meiotic prophase and remains as univalent. The fate of univalent B is variable. In majority of PMCs the single B moves to one of the telophasic nucleus in undivided condition. In subsequent II meiotic division B-chromosome divides normally, with the result out of 4 tetrad nuclei two of them contain lB each, and others contain no B-chromosomes.

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The present study deals with the extent of genome size variation and evolution in some species of Dalbergia. The interspecific 4C DNA content variation has been analyzed in 30 accessions belonging to ten species of Dalbergia. The 4C DNA content in ten Dalbergia species ranges from 5.85 pg in D. lanceolaria to 7.88 pg in D. horrida, about 1.3 fold variation is apparent at a constant chromosome number 2n=2x=20. ANOVA test reveals significant variation between species. Like other woody angiospermic taxa, tree species of Dalbergia exhibit small genome size ranging from 5.85 pg in D. lanceolaria to 7.22 pg in D. sissoides. In contrast, the shrubs and climbers of this genus also reveal a narrow range of genome size variation from 7.36 pg in D. rubiginosa to 7.88 pg in D. horrida The climber species of this genus exhibits higher DNA amount than the tree species. The present investigation indicate that lianas or climber species of Dalbergia have evolved from tree species through evolutionary increase in genome size. The extent of DNA amount differences between the Dalbergia species has been discussed in the light of their interrelationships and diversity.