RESUMO
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.
Assuntos
Manihot/genética , Agricultura/métodos , Cruzamento , Produtos Agrícolas/genética , Cruzamentos Genéticos , Secas , Genes de Plantas , Manihot/química , Floema/fisiologia , Fenômenos Fisiológicos Vegetais , Ploidias , Xilema/fisiologiaRESUMO
A total of 98 Manihot species have been recognized in the genus. All of them are native to the tropics of the New World, particularly Brazil and Mexico. The cultigen, Manihot esculenta Crantz (cassava), grows throughout the lowland tropics. Wild species vary in growth habit from acaulescent or short shrubs to tree-like. Because of their adaptations to different conditions, they are gene reservoirs for tackling many abiotic and biotic stresses such as improving root quality and resistance to diseases. They have been used successfully by the first author for improving protein content, seed-fertility, apomixis, resistance to mealy bug, and tolerance to drought. A table of the most important species from an economic viewpoint is presented.
Assuntos
Produtos Agrícolas/economia , Produtos Agrícolas/genética , Manihot/genética , Adaptação Fisiológica , Evolução Biológica , Brasil , Produtos Agrícolas/fisiologia , Cruzamentos Genéticos , Variação Genética , Hibridização Genética , Manihot/anatomia & histologia , Manihot/classificação , Manihot/fisiologia , México , Folhas de Planta/anatomia & histologia , Reprodução Assexuada/genéticaRESUMO
A total of 98 Manihot species have been recognized in the genus. All of them are native to the tropics of the New World, particularly Brazil and Mexico. The cultigen, Manihot esculenta Crantz (cassava), grows throughout the lowland tropics. Wild species vary in growth habit from acaulescent or short shrubs to tree-like. Because of their adaptations to different conditions, they are gene reservoirs for tackling many abiotic and biotic stresses such as improving root quality and resistance to diseases. They have been used successfully by the first author for improving protein content, seed-fertility, apomixis, resistance to mealy bug, and tolerance to drought. A table of the most important species from an economic viewpoint is presented.
