Recursos GenŽticos e Biotecnologia. Embrapa. Brasil.. BRASIL.
Francisco J. L. Arag‹o1& Josias C. Faria2
1Embrapa Recursos GenŽticos e Biotecnologia, PqEB W5 Norte, 70770-900, Bras’lia, DF, Brazil. 2Embrapa Arroz e Feij‹o, Rod. GO-462, km 12, 75375-000 Santo Ant™nio de Goi‡s, GO, Brazil,
RESUMEN (ABSTRACT)
Using the biolistic process we have developed a transformation system to insert exogenous DNA sequences into common bean genome. We are using this system to introduce agronomic traits involved with virus and fungus resistance, herbicide tolerance, abiotic stress tolerance and nutritional improvement. We explored the concept of using an RNA interference construct to silence the sequence region of the AC1 viral gene from Bean golden mosaic geminivirus (BGMV) and generate highly resistant transgenic common bean plants. Two lines presented high resistance upon inoculation at high pressure and at a very early stage of plant development. Studies on the behavior of the transgenic common bean lines under field conditions were conducted. The first field trails were carried out during the agricultural seasons of 2006, 2007 and 2008 in the state of Goi‡s, Brazil. Results confirmed earlier greenhouse observations. The highest average incidence of viral infection in control plots was 18% in 2007 and 83% in 2008. Non-transgenic plants revealed characteristic severe symptoms of the golden mosaic disease and no symptoms were observed in the transgenic plants. One line has been evaluated in the field in three distinct regions from Brazil. The results showed that no significant differences were observed in the seed germination, initial plant height, width of the leaves, flowering time, yield, number of seeds per pod and 100-seed weight. Biosafety evaluations are being carried out, taking into account the demands of the Brazilian Biosafety Committee and other regulatory authorities in order to obtain authorization to commercially release the first transgenic bean varieties.