Esquivel-Naranjo E U, Herrera-Estrella A
Departamento de Ingeniería Genética, Cinvestav Campus Guanajuato, Km 9.6 Libramiento Norte Carretera Irapuato-León, A.P. 629, Irapuato 36500, Guanajuato, Mexico.
Laboratorio Nacional de Genómica para la Biodiversidad, Cinvestav Campus Guanajuato, Km 9.6 Libramiento Norte Carretera Irapuato-León, A.P. 629, Irapuato 36500, Guanajuato, Mexico.
Microbiology (Reading). 2007 Nov;153(Pt 11):3909-3922. doi: 10.1099/mic.0.2007/007302-0.
Light is an environmental factor that regulates pivotal processes in living organisms, and appropriate perception is key to adaptation to the environment. Blue light activates asexual reproduction in Trichoderma atroviride through transcription factors BLR-1 and BLR-2 which regulate light-responsive genes. Here, we show that blr-2 expression is a limiting factor for photo-perception and photo-transduction. Overexpression of blr-2 resulted in increased photoconidiation and stronger expression of light-induced genes. In contrast, overexpression of blr-1 resulted in reduced photoconidiaton and weaker expression of light-induced genes. blr-2 overexpression caused a marked reduction of growth when the fungus was grown under defined photoperiods, including a period of strong sensitivity to light, followed by a period of insensitivity. Long periods of incubation under this condition permitted recovery of a rhythmic growth similar to that of the wild-type. In addition, blr-2 expression is apparently regulated at the post-transcriptional level through the BLR proteins and its expression level is BLR-1-dependent even in the dark. Finally, we demonstrated that blr-2 overexpression caused higher sensitivity to blue light and we therefore propose that the preformation of BLR-1/BLR-2 complexes is key to adequate light perception in T. atroviride.
光是一种调节生物体内关键过程的环境因素，而适当的光感知是适应环境的关键。蓝光通过调节光响应基因的转录因子BLR-1和BLR-2激活绿色木霉的无性繁殖。在此，我们表明blr-2的表达是光感知和光转导的限制因素。blr-2的过表达导致光产孢增加以及光诱导基因的表达增强。相反，blr-1的过表达导致光产孢减少以及光诱导基因的表达减弱。当真菌在特定光周期下生长时，blr-2的过表达会导致生长显著减少，包括一段对光高度敏感的时期，随后是一段不敏感时期。在此条件下长时间培养可使真菌恢复类似于野生型的节律性生长。此外，blr-2的表达显然在转录后水平通过BLR蛋白受到调控，并且即使在黑暗中其表达水平也依赖于BLR-1。最后，我们证明blr-2的过表达导致对蓝光的更高敏感性，因此我们提出BLR-1/BLR-2复合物的预先形成是绿色木霉充分光感知的关键。
