RESUMO
Information on anatomical structure is needed by breeders working on improvement for drought tolerance. For studying the effect of polyploidy on cassava anatomy and its significance to tolerance to drought, we induced a polyploidy type of a selected clone (UnB 530) by applying an aqueous solution of 0.2% colchicine on lateral buds for a period of 12 h. The stem identified as tetraploid was propagated to produce the whole plant. Free-hand cross-sections of the median portion between stem internodes were made. They were clarified using 50% sodium hypochlorite solution, stained with 1% safranin-alcian blue, passed through an ethanol series and butyl acetate and mounted in synthetic resin. The tetraploid type showed more prismatic and druse crystals in the cortical parenchyma, and its pericycle fibers had thicker walls. The secondary xylem of tetraploid types was wider than diploid ones, having thinner walls and less starch.
Assuntos
Manihot/anatomia & histologia , Manihot/genética , Poliploidia , Parede Celular/metabolismo , Desastres , Regulação da Expressão Gênica no Desenvolvimento , Regulação da Expressão Gênica de Plantas , Manihot/crescimento & desenvolvimento , Caules de Planta/anatomia & histologia , Caules de Planta/genética , Caules de Planta/crescimento & desenvolvimento , Amido/metabolismoRESUMO
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.
Assuntos
Cruzamentos Genéticos , Manihot/genética , Produtos Agrícolas/genética , Adaptação Fisiológica , Evolução Biológica , Brasil , Folhas de Planta/anatomia & histologia , Variação Genética , Hibridização Genética , Manihot/anatomia & histologia , Manihot/classificação , Manihot/fisiologia , Reprodução Assexuada , Produtos Agrícolas/economia , Produtos Agrícolas/fisiologiaRESUMO
Information on anatomical structure is needed by breeders working on improvement for drought tolerance. For studying the effect of polyploidy on cassava anatomy and its significance to tolerance to drought, we induced a polyploidy type of a selected clone (UnB 530) by applying an aqueous solution of 0.2% colchicine on lateral buds for a period of 12 h. The stem identified as tetraploid was propagated to produce the whole plant. Free-hand cross-sections of the median portion between stem internodes were made. They were clarified using 50% sodium hypochlorite solution, stained with 1% safranin-alcian blue, passed through an ethanol series and butyl acetate and mounted in synthetic resin. The tetraploid type showed more prismatic and druse crystals in the cortical parenchyma, and its pericycle fibers had thicker walls. The secondary xylem of tetraploid types was wider than diploid ones, having thinner walls and less starch.
