The effect of cotyledons on chloroplast development in primary leaves of Phaseolus vulgaris

Cuando se deja desarrollar normalmente las semillas de Phaseolus vulgaris hasta alcanzar la madurez en la planta, los plastidios de las hojas primordiales del embrion contenido en la semilla no se desarrollan hasta convertirse en cloroplastos maduros. semillas en desarrollo de las plantas progenitoras, se desprenden los cotiledones y se cultivan los ejes embrionicos en agar, los plastidios de las hojas primordiales se transforman en cloroplastos maduros en 7 dias. plastidios no alcanzan a diferenciarse cuando se dejan los cotiledones adheridos a los embriones y se los cultiva en esta forma durante una semana en agar. El desarrollo lamelar de las hojas primordiales de semillas latentes germinadas en agar comienza mas temprano en plantulas cuyos cotiledones se eliminaron que en plantulas con cotiledones adheridos, aunque no hay diferencias significativas entre los 2 grupos de plantulas en cuanto al tiempo requerido para que los cloroplastos maduren totalmente. parece ser que la presencia de los cotiledones inhibe inicialmente la diferenciacion de los plastidios en las hojas primordiales de semillas de Phaseolus en desarrollo. durante la maduracion y latencia de la semilla. spa

When seeds of Phaseolus vulgaris are allowed to develop normally in fruits on the mature plant, the plastids in the primary leaves of the embryo within the seed do not develop into mature chloroplasts. However, when the developing seeds are removed from the parent plants, the cotyledons detached and the embryonic axes grown on agar, primary leaf plastids differentiate into mature chloroplasts with in 7 days. In embryos with attached cotyledons and similarly grown for a week on agar, plastids fail to differentiate. In primary leaves of dormant seeds allowed to germinate on agar, lamellar development begins earlier in seedlings from which the cotyledons have been removed than in those with attached cotyledons although there is no significant difference between the 2 groups of seedlings in the time required for the chloroplasts to become fully mature. Plastid differentiation in primary leaves of developing seeds of Phaseolus therefore appears to be inhibited initially by the presence of the cotyledons. This inhibitory effect apparently declines during seed ripening and dormancy. (AS) eng