ABSTRACT. We examined the stem anatomy of Manihot esculenta Crantz and its hybrid with M. oligantha Pax. Cross-sections were stained with safranin-alcian blue. Manihot esculenta and its hybrid were found to have the same vascular structure in bicollateral bundles with internal phloem, which has been associated with drought resistance in other plant groups. If this association is established for cassava, it would facilitate the selection of lines that are more adapted to arid regions. This is the first report of internal phloem in this genus.
ABSTRACT. A molecular, anatomical and cytogenetic study of an interspecific hybrid between Manihot esculenta (cassava) and the wild species M. oligantha was carried out. Cytogenetics revealed relatively complete chromosome pairing and high viability of the pollen grains. Ovule structure examined by the clearing method showed polyembryony in 2.7% of the ovules. Doubling of the chromosome number resulted in an increase in polyembryony of up to 18% and a reduction in pollen viability. Multivalent formation was also observed. An anatomical study of stems of diploid and tetraploid hybrids showed a larger number of vascular bundles in the tetraploid type.
The objective of this research was to examine how much polyploidy may affect seed and root formation in cassava interspecific hybrids Manihot esculenta Crantz xM. oligantha Pax. A polyploid type was induced by colchicine treatment to lateral buds followed by propagating vegetatively arising stems. Cytogenetic and anatomical analyses were made on both polyploid and diploid types. The polyploid type showed extensive chromosome pairing and pollen viability. Multiembryonic ovule frequency increased in polyploid plants. Stalks became woody and propagation through roots difficult, the edible roots increased, however, in size.
Summary Cytogenetical analysis of the interspecific hybrid between M. esculenta (cassava) and M. oligantha revealed a fair chromosome pairing and a high viability of pollen grain. Studying ovule structure by clearing method showed multiembryony in 2.7% of ovules studied. Doubling chromosome number resulted in an increase of multiembryony up to 18% and reduction of pollen viability. Multivalent formation was observed too. In anatomical stem study of diploid and tetraploid hybrids it was noted larger number of vascular bundles in tetraploid type.
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