Endogenous GUS-like activity in Capsicum chinense Jacq.
Laura Yesenia Solís-Ramos*#
Enrique Castaño de la Serna
Financial support: Consejo Nacional de Ciencia y Tecnología (CONACYT), México and Dirección de Intercambio Académico de la Secretaría de Relaciones Exteriores from México.
Keywords: Agrobacterium tumefaciens, β-glucuronidase, Capsicum chinense, gene uidA.
Present address: #Escuela de Biología, Universidad de Costa Rica, P.O. Box 11501-2060, San Pedro, Costa Rica. ¥Consejo de Ciencia y Tecnología del Estado de Yucatán (CONCYTEY), Mérida, Yucatán, México.
The gene uidA, codes for β-glucuronidase, which is one of the reporters more frequently utilized in transgenic plants. However, this can only be use if the selected organism does not present endogenous GUS-like activity. In tissues of C. chinense we found a GUS-like activity showing different levels of intensity. Histochemical screening showed that endogenous GUS-like activity decreased, or reduced significantly, in almost all tissues with exception of stament, when phosphate buffer was adjusted to pH 8. Subsequently, C. chinense zygotic embryo explants were transient transformed with Agrobacterium tumefaciens LBA4404 (pCAMBIA2301) and plantlets regenerated were histochemically stained in phosphate buffer pH 8. Observations of incubated tissues of C. chinense regenerants showed blue staining, suggesting expression of uidA. Incubated tissues of non-transformed regenerants did not show blue staining in phosphate buffer pH 8. The results show that for transformation experiments of C. chinense with uidA gene, pH 8 is recommended for histochemical staining.