RESUMO
The central role of multisubunit tethering complexes in intracellular trafficking has been established in yeast and mammalian systems. However, little is known about their roles in the stress responses and the early secretory pathway in Arabidopsis. In this study, Maigo2 (MAG2), which is equivalent to the yeast Tip20p and mammalian Rad50-interacting protein, is found to be required for the responses to salt stress, osmotic stress and abscisic acid in seed germination and vegetative growth, and MAG2-like (MAG2L) is partially redundant with MAG2 in response to environmental stresses. MAG2 strongly interacts with the central region of ZW10, and both proteins are important as plant endoplasmic reticulum (ER)-stress regulators. ER morphology and vacuolar protein trafficking are unaffected in the mag2, mag2l and zw10 mutants, and the secretory marker to the apoplast is correctly transported in mag2 plants, which indicate that MAG2 functions as a complex with ZW10, and is potentially involved in Golgi-to-ER retrograde trafficking. Therefore, a new role for ER-Golgi membrane trafficking in abiotic-stress and ER-stress responses is discovered.
Assuntos
Ácido Abscísico/fisiologia , Proteínas de Arabidopsis/metabolismo , Arabidopsis/fisiologia , Proteínas de Transporte/metabolismo , Retículo Endoplasmático/metabolismo , Complexo de Golgi/metabolismo , Estresse Fisiológico , Ácido Abscísico/metabolismo , Arabidopsis/citologia , Arabidopsis/genética , Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Proteínas de Transporte/genética , Regulação da Expressão Gênica de Plantas , Genes Reporter , Germinação , Peptídeos e Proteínas de Sinalização Intracelular , Células do Mesofilo , Mutagênese Insercional , Pressão Osmótica , Transporte Proteico , Protoplastos , Sais , Plântula/citologia , Plântula/genética , Plântula/metabolismo , Plântula/fisiologia , Sementes/citologia , Sementes/genética , Sementes/metabolismo , Sementes/fisiologia , Transdução de Sinais , Técnicas do Sistema de Duplo-Híbrido , Vacúolos/metabolismoRESUMO
Small heat shock proteins (smHSPs) play important and extensive roles in plant defenses against abiotic stresses. We cloned a gene for a smHSP from the David Lily (Lilium davidii (E. H. Wilson) Raffill var. Willmottiae), which we named LimHSP16.45 based on its protein molecular weight. Its expression was induced by many kinds of abiotic stresses in both the lily and transgenic plants of Arabidopsis. Heterologous expression enhanced cell viability of the latter under high temperatures, high salt, and oxidative stress, and heat shock granules (HSGs) formed under heat or salinity treatment. Assays of enzymes showed that LimHSP16.45 overexpression was related to greater activity by superoxide dismutase and catalase in transgenic lines. Therefore, we conclude that heterologous expression can protect plants against abiotic stresses by preventing irreversible protein aggregation, and by scavenging cellular reactive oxygen species.