Las concentraciones de AIA en miligramos por litro se indican junto con las curvas 0, 1, 4 y La cinetina sola tiene poco efecto en el crecimiento del tejido indiferenciado de tabaco en cultivo un callo. El floema y el xilema se desarrollan en presencia de giberelinas y auxinas. Las plantas capaces de detectarlo exhiben fotoperiodicidad.
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Over recent decades, Over recent decades, hormones have been identified as essential factors in ovule formation, as they play a key role in determining their final number. Especially, hormones such as auxins, brassinosteroids or cytokinins are considered very important in this process, where they have a positive effect on the ovule development. However, although the role of gibberellins GAs on the ovule development has not yet been described, there are indications that these hormones are essential in this process, having a negative effect on the final number of ovules, what has been studied by analyzing mutants that have changes in hormone levels of GAs or in its response.
In this study, it is intended to affirm the negative role of GAs on the ovule development in tomato plants, using the transgenic lines L1i and L5i, where GA2ox genes, which encode gibberellin inactivating enzymes GA 2-oxidases, have been silenced.
To do this, the phenotypic alterations in the number or morphology of the ovules, seeds and ovaries between transgenic lines, L1i and L5i, and the control MT were studied, as well as variations in the levels of gibberellins and other hormones auxins, abscisic acid and jasmonic acid. The results of these studies show that silencing GA2ox genes leads to increased levels of bioactive gibberellin GA1 and decreased inactive products GA51, GA34, GA29 and GA8 in reproductive tissues of transgenic tomato lines, which was expected as a result of silencing GA 2-oxidases.
Regarding the levels of auxins, abscisic acid and jasmonic acid, there were no differences relative to the control, suggesting that GAs do not influence the metabolism of these hormones. Moreover, the phenotypic study revealed significant differences only in the transgenic line L5i, where it was observed that variations in the levels of GAs resulted in smaller ovules, as well as a fewer number of ovules and seeds per fruit.
This fact could confirm the negative role of gibberellins on the ovule number and its development. Concerning the L1i line, although variations in their levels of GAs were observed relative to MT, it did not show phenotypic alterations, which could be due to differences between the two transgenic lines in localization of the transgene.
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Capítulo 46. El crecimiento y desarrollo en las plantas