01624naa a2200145 a 450000100080000000500110000800800410001910000110006024500450007126000090011652012230012570000170134870000230136577300900138816518972004-04-15       1998    bl uuuu     u00u1 u    #d1 aLI, HQ  aEngeneering leaf life length in cassava.  c1998  aAbstract: Cassava leaves are an important protein source in many areas, but can only be harvested at long intervals, in order not to affect root production adversely. On the other hand many cassava cultivars have a suboptimal stay-green index, which traditional breeding has not been able to improve. This project addresses the possibility of prolonging the life span of individual cassava leaves by use of physiologically autoregulated phytohormone production to delay senescence of leaves. By prolonging leaf both more frequent leaf harvesting and improved stay-green index could be achieved. A binary vector, containing a gene from Agrobacterium tumefaciens encoding cytokinin biosynthesis (ipt) driven by a senescence specific promoter (sag from Arabidopsis) was made and used to transform cassava and tobacco with Agrobacterium. After cocultivation with  Agrobacterium transgenic geneticin resistant cassava and tobacco plants were regenerated. PCR and Southern analysis were performed to confirm the transgenic nature of the regenerated plants. The phenotype of the tobacco plants, used as a positive control, shows that the life span of leaves of the transgenic plants is longer than that of the control plants.1 aPOTRYKUS, I.1 aPUONTI-KAERLAS, J.  tRevista Brasileira de Mandioca, Cruz das Almasgv. 17, p. 31, nov., 1998.,Suplemento.