RESUMO
The aim of this work was to study the physiological mechanisms of dormancy and sprouting during post-harvest of garlic (Allium sativum L.) microbulblets produced by meristem culture of garlic seed cloves. The morphological changes occurring in garlic microbulblets were assessed from harvest till sprouting in relation with peroxidase activity and levels of gibberellins. Also the effect of a cold treatment (30 days at 4 degrees C) given 30 days after harvest was studied. The results showed that during the state of dormancy in garlic microbulblets formation of the leaf primordia and vascular differentiation of the storage leaf occurred, while increases of peroxidase activity and low levels of GA3 (the only active gibberellin identified) were found. At the end of dormancy the sprouting channel was formed, vascular differentiation established, and peaks of soluble peroxidase activity as well as of GA3 were observed. At day 90 post-harvest, garlic microbulblets showed physiologically mature and able to sprout. Further on, bud expansion and decrease of GA3 levels characterized sprouting of the microbulblets. The cold treatment enhanced GA3 levels and anticipated the sprouting process.
Assuntos
Alho/fisiologia , Giberelinas/metabolismo , Peroxidases/metabolismo , Estruturas Vegetais/citologia , Plantas Medicinais , Diferenciação Celular , Células Cultivadas , Alho/citologia , Alho/enzimologia , Alho/crescimento & desenvolvimento , Cromatografia Gasosa-Espectrometria de Massas , Folhas de Planta/citologia , Folhas de Planta/crescimento & desenvolvimento , Folhas de Planta/metabolismo , Estruturas Vegetais/fisiologiaRESUMO
The aim of this paper was to evaluate an acute dose of gamma-rays (10 Gy) on post-dormant garlic seed cloves in terms of total DNA, total RNA, total protein and soluble carbohydrates in order to correlate these levels with sprouting inhibition induced by gamma-irradiation. Decreases in total DNA content were found in inner sprouts immediately and 100 days after irradiation. The total RNA and protein contents and the carbohydrate content of the storage leaf or the inner sprout were not affected by gamma-irradiation. The results support the notion that in post-dormant garlic seed cloves, DNA content and its behaviour seem to be among the sensitive cellular responses to radiation.
Assuntos
Alho/efeitos da radiação , Plantas Medicinais , Carboidratos/química , Conservação de Alimentos/métodos , Raios gama , Alho/crescimento & desenvolvimento , Ácidos Nucleicos/química , Proteínas/química , Fatores de TempoRESUMO
The effects of an acute dose of gamma-rays (10 Gy) to post-dormant garlic cloves on inner sprout growth and changes in peroxidases and soluble proteins were evaluated up to 100 days of storage in darkness at 19 +/- 1 degree C and 42 +/- 2% relative humidity. Radiation-induced inhibition of sprout growth became evident after 25 days of treatment and was synchronous with a marked increase in peroxidase activity. Thin-layer isoelectric focusing revealed that radiation induced an increase in the number of anodic peroxidase isoenzymes at 100 days, suggesting modifications in the vascularization process. Neither the soluble protein content nor the protein pattern were affected by irradiation. These results are discussed in terms of a possible mediating effect of peroxidase on radiation-induced sprout inhibition in garlic.