Shade Avoidance

The presence of neighboring vegetation modifies the light environment experienced by plants, generating signals that are perceived by phytochromes and cryptochromes. These signals cause large changes in plant body form and function, including enhanced growth of the hypocotyl and petioles, a more erect position of the leaves and early flowering in Arabidopsis thaliana. Collectively, these so-called shade-avoidance responses tend to reduce the degree of current or future shade by neighbors. Shade light signals increase the abundance of PHYTOCHROME INTERACTING FACTOR 4 (PIF4) and PIF5 proteins, promote the synthesis and redirection of auxin, favor the degradation of DELLA proteins and increase the expression of auxin, gibberellins and brassinosteroid-promoted genes, among other events downstream the photoreceptors. Selectively disrupting these events by genetic or pharmacological approaches affects shade-avoidance responses with an intensity that depends on the developmental context and the environment. Shade-avoidance responses provide a model to investigate the signaling networks used by plants to take advantage of the cues provided by the environment to adjust to the challenges imposed by the environment itself

A search for homologues of plant photoreceptor genes and their signaling partners in the sugarcane expressed sequence tag (Sucest) database

A search in the sugarcane expressed sequence tag (SUCEST) database for homologues of plant genes involved in photo-sensory mechanisms was carried out using the basic local alignment tool (BLAST). Our results shown that known elements (phytochromes, cryptochromes and phototoprin) present in Arabidopsis and other higher plants were detected with low e-values. We also searched for proteins interacting with photoreceptors in primary or downstream signaling events. One putative homologue for a protein postulated to be a primary element in phytochrome signaling pathways was identified, as were other candidates for downstream interacting factors.<br>A partir dos dados do projeto de sequenciamento de Ests da Cana de Açúcar (Sucest/FAPESP) e utilizando BLAST (tblastn) como ferramenta, foi realizada uma busca de genes homólogos aos elementos envolvidos nos processos de foto-recepção e já descritos para outras plantas, principalmente Arabidopsis. Foram obtidas altas identidades para os fitocromos A, B e C assim como para os criptocromos 1, 2 e a fototropina. Diversos elementos identificados como reguladores primários ou secundários na transdução de sinal de foto-receptores também foram identificados com baixos valores de E-value