InactivaciĆ³n espacio-temporal de auxina en polen utilizando el gen bacteriano IAAL y su efecto en el desarrollo de la flor en Arabidopsis thaliana
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2017
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es
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Universidad AndrƩs Bello
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Resumen
En Arabidopsis, el desarrollo del estambre se divide en dos etapas con temporalidades
distintas. La etapa temprana involucra una fase de formaciĆ³n y morfogĆ©nesis; mientras que la
tardĆa consiste en tres procesos de desarrollo diferentes: la dehiscencia de la antera, la
maduraciĆ³n del polen y la elongaciĆ³n del filamento. La interrupciĆ³n de cualquiera de estos
procesos resulta en esterilidad masculina, por lo que se trata de procesos esenciales para la
productividad de muchas plantas. Se conoce que el gametofito masculino es un tejido que
acumula auxina, hormona que participa en diferentes aspectos del desarrollo de la planta, pero se
desconoce su rol en el caso del desarrollo del polen. Con el objetivo de entender mejor el rol que
tiene la auxina durante el desarrollo del polen, se generaron plantas transgƩnicas de Arabidopsis
thaliana que expresan el gen iaaL, que codifica para una proteĆna que es capaz de conjugar el
IAA activo, generando una forma biolĆ³gicamente inactiva de la hormona y, de esta forma,
generando un tejido deficiente en auxina. El gen iaaL fue expresado exclusivamente en el polen,
utilizando promotores con distintas temporalidades de expresiĆ³n āque habĆan sido caracterizados
previamenteā para conocer si existe una ventana temporal durante el desarrollo del polen en la
cual la acumulaciĆ³n de la hormona es de importancia. Las plantas resultantes presentaron polen
no viable, elongaciĆ³n del filamento normal y no presentaron alteraciones funcionales en el
proceso de dehiscencia. AdemĆ”s presentaron frutos mĆ”s pequeƱos y con menor nĆŗmero semillas
que las plantas silvestres. Por otro lado, algunas plantas mostraron ausencia de los estambres
cortos y, en este Ćŗltimo caso, se detectĆ³ ademĆ”s un menor desarrollo de las glĆ”ndulas de nĆ©ctar.
Estos resultados sugieren que la auxina que se acumula en el polen durante su desarrollo (en la
etapa floral 11) podrĆa ser importante en la viabilidad del mismo; que los promotores podrĆan
presentar actividad en la etapa temprana del desarrollo del estambre; y finalmente, reflejan la
posible existencia de una relaciĆ³n entre la presencia del estambre corto y el desarrollo de la
glƔndula de nƩctar lateral, apoyando modelo del flujo de auxina propuesto desde la antera a los
otros tejidos florales.
In Arabidopsis, the first phase of stamen development involves morphogenesis, histospecification and pollen mother cells generation. Later, during the late phase of stamen development, microspores go through a division process in the anther, producing mature pollen grains, stamen filaments elongate and the anther dehiscence occurs, releasing the pollen grains at anthesis. Interruption in any of this processes generate male sterility, affecting plant productivity. Male gametophyte is a tissue that accumulates auxin, this hormone has an important role in plant development but its role during pollen development remains poorly understood. To assess the contribution of auxin accumulated in pollen during its development, Arabidopsis thaliana transgenic plants were generated expressing the iaaL gene, which codificates for a protein capable of deplete active IAA, generating a biological inactive form of the hormone leading to an auxin deficient tissue. The iaaL gene was expressed in a pollen specific manner, using tissuespecific promoters previously characterized and also with different expression temporalities. To assess the contribution of auxin accumulated in pollen during the different stages of its development. The generated plants presented aborted pollen and smaller fruits with less seeds than the wild type. The process of anther dehiscence and filament elongation were normal. On the other hand, some plants showed absence of the short stamens, and when this was the case, the nectaries were underdeveloped. This results suggested that auxin accumulated during pollen development, possibly during intermediate stages (floral stage 11), might have a role during the pollen maturation, also that the selected promoters may present activity in early stages of stamen development. Finally this results suggest a link between short stamen presence and nectary gland development, supporting the auxin flow model proposed from the anther to other floral tissues.
In Arabidopsis, the first phase of stamen development involves morphogenesis, histospecification and pollen mother cells generation. Later, during the late phase of stamen development, microspores go through a division process in the anther, producing mature pollen grains, stamen filaments elongate and the anther dehiscence occurs, releasing the pollen grains at anthesis. Interruption in any of this processes generate male sterility, affecting plant productivity. Male gametophyte is a tissue that accumulates auxin, this hormone has an important role in plant development but its role during pollen development remains poorly understood. To assess the contribution of auxin accumulated in pollen during its development, Arabidopsis thaliana transgenic plants were generated expressing the iaaL gene, which codificates for a protein capable of deplete active IAA, generating a biological inactive form of the hormone leading to an auxin deficient tissue. The iaaL gene was expressed in a pollen specific manner, using tissuespecific promoters previously characterized and also with different expression temporalities. To assess the contribution of auxin accumulated in pollen during the different stages of its development. The generated plants presented aborted pollen and smaller fruits with less seeds than the wild type. The process of anther dehiscence and filament elongation were normal. On the other hand, some plants showed absence of the short stamens, and when this was the case, the nectaries were underdeveloped. This results suggested that auxin accumulated during pollen development, possibly during intermediate stages (floral stage 11), might have a role during the pollen maturation, also that the selected promoters may present activity in early stages of stamen development. Finally this results suggest a link between short stamen presence and nectary gland development, supporting the auxin flow model proposed from the anther to other floral tissues.
Notas
Tesis (Magister en BiotecnologĆa)
Palabras clave
BiotecnologĆa Vegetal, GenĆ©tica Vegetal, Arabidopsis Thaliana