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Doctoral Thesis
DOI
https://doi.org/10.11606/T.11.2020.tde-20200111-134933
Document
Author
Full name
Moacir Pasqual
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
Piracicaba, 1985
Supervisor
Title in Portuguese
Regeneração de plantas "in vitro" e radiossensitividade de tecidos
Keywords in Portuguese
REGENERAÇÃO IN VITRO
CITROS
RADIOSSENSITIVIDADE
TECIDOS NUCELARES
Abstract in Portuguese
Existem diversas limitações, como apomixia, esterilidade gamética e incompatibilidade, ao melhoramento das espécies cítricas, razão da maioria das cultivares ter se originado por mutações espontâneas. Procurou-se através deste trabalho, determinar uma metodologia para regeneração de plantas a partir de nucelos, calos nucelares e gemas axilares, bem como, para induzir mutantes com o uso de radiação gama, de forma a explorar os benefícios oferecidos pelas técnicas de cultura de tecidos e células. Nucelos da cv. 'Valência' e óvulos abortivos da cv. 'Pera' foram cultivados "in vitro" em meio "MS" adicionado de várias substâncias reguladoras do crescimento. Tanto nucelos extraídos de frutos de 'Valência' com aproximadamente 12 semanas após a polinização, como calos oriundos destes mesmos nucelos, foram submetidos a diferentes doses de radiação gama e cultivados "in vitro". Gemas axilares de 'Valência' e 'Trifoliata' foram cultivadas em meio "MS" suplementado com diversas combinações de uma auxina e uma citocinina. Houve diferenciação de embrióides tanto diretamente do nucelo como via formação de calos em 'Valência' e 'Pera' e ótima multiplicação de gemas axilares em 'Valência' e 'Trifoliata'. A adição de auxinas e citocininas inibe a embriogênese em nucelos. O aumento das doses de radiação gama sobre nucelos e calos nucelares provoca uma redução do número de embrióides, mais acentuada se aplicadas em fases posteriores a inoculação. Pode-se definir uma dose de 1,0 a 2,0 kR para tratamento de nucelos em trabalhos de indução de mutações. A irradiação apenas do meio de cultura aumenta a proliferação de calos. Nota-se um elevado Índice de anormal idade nos embrióides principalmente com doses mais elevadas de raios gama. O enraizamento de embrióides é melhor estimulado por GA3-1,0 ou NAA-0,1 mg/l. Para a cv. 'Valência', a multiplicação de gemas foi mais estimulada por NAA-0,2 + BAP-0,2 mg/l e o enraizamento de brotos por NAA-0,1 a 1,0 + IBA-2,0 mg/l, enquanto que, para 'Trifoliata' o melhor índice de multiplicação de gemas se deu com NAA-1,0 + BAP-1,0 mg/l e de enraizamento de brotos com IBA-1,0 a 2,0 mg/l ou NAA-5,0 + BAP-0,1 mg/l ou ainda NAA-1,0 + IBA-2,0 mg/l.
Title in English
"In vitro" regeneration of plants and radiosensitivity of nucellar tissues in citrus
Abstract in English
There are various limiting factors, such as apomixis, gametic sterility and incompatibility in the breeding of Citrus species. In view of this, the majority of Citrus cultivars have originated from spontaneous mutation. In the present work, attempts were made to determine a methodology to regenerate plants from nucelli, nucellar callus and axillary buds, and also to induce mutants by gamma radiation in order to explore the benefits offered by the technology of tissue and cell culture. Nucelli of the cultivar 'Valencia' and abortive ovules of the cultivar 'Pera' were cultured "in vitro" on the "MS" medium, supplemented with various growth regulators. Both nucelli, extracted from the fruits of 'Valencia' approximately 12 weeks after pollination, and callus originated from these nucelli, were irradiated with different doses of gamma-rays and cultured "in vitro". Axillary buds of 'Valencia' and 'Trifoliata' were cultured on the "MS" medium supplemented with various combinations of one auxin and one cytokinin. Differentiation of embryoids was observed directly from nucelli as well as from nucellar callus in 'Valencia' and 'Pera', and excellent multiplication of axillary buds of 'Valencia' and 'Trifoliata' was also observed. Addition of auxin and cytokinin inhibits the embryogenesis of nucelli. Increase of gamma-radiation dose on nucelli and nucellar callus caused a reduction in number of embryoids formed, and this was more noticeable when gamma-radiation was applied in posterior periods after inoculation. It has been concluded that gamma-ray doses of 1.0 to 2.0 kR are adequate to the treatment of nucelli in mutation breeding. High frequency of abnormality of embryoids was observed with higher doses of gamma-ray. The rooting of embryoids was stimulated with the addition of GA3-1.0 or NAA-0.1 mg/l. For the cultivar 'Valencia', multiplication of buds was stimulated with the addition of NAA-0.2 + BAP-0.2 mg/l, and the rooting of shoots with the addition of NAA-0.1 to 0.2 + IBA-2.0 mg/l, while for 'Trifoliata' the highest frequency of bud multiplication occurred with NAA-1.0 + BAP-1.0 mg/l and of rooting of shoots with IBA-1.0 to 2.0 mg/l or NAA-5.0 + BAP-0.1 mg/l or NAA-1.0 + IBA-2.0 mg/l.
 
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Publishing Date
2020-01-11
 
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