Crytology and Morphology of a Tetraploid Sorghum Population Recovered from a Saccharum ✕ Sorghum Hybrid1
- S. C. Gupta,
- J. R. Harlam and
- J. M. J. de Wet2
Sugarcane (Saccharum sp.) with 2n = ca. 112 chromosomes was crossed with diploid (2n = 20) sorghum (Sorghum bicolor (L.) Moench), and their hybrids were backcrossed twice with diploid and twice with tetraploid (2n = 40) sorghum. The BC2 individuals, so obtained, were selfed twice to produce a recovered tetraploid sorghum population (BC4F3). Fifty-one BC4F3 individuals, sugarcane and the sorghum parents, were studied cytologically and morphologically. Irregular cytological behavior of recovered sorghum plants, characterized by an increase in bivalent formation and decrease in tetravalent formation at diakinesis (in comparison to their tetraploid ‘Rio’ sorghum parent) indicated that the sorghum chromosomes may be contaminated with sugarcane genetic material. Morphological data were analyzed by cluster analysis, principal component analysis, univariate analysis of variance, F-test, and t-test to study the variability in the hybrid populations and to test the significance of morphological differences among groups. Modified recovered tetraploid sorghums had various combinations of Saccharum characteristics superimposed on a basic Sorghum morphology. Sixteen of 26 plant characters studied were influenced by sugarcane genetic material to varying degrees and frequencies. The presence of these sugarcane characters in recovered sorghums indicated intergenomic genetic exchange.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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