RESUMEN
Cell-specific expression patterns of the Eucalyptus gunnii cinnamoyl coenzymeA reductase (EgCCR) and cinnamyl alcohol dehydrogenase (EgCAD2) promoters were analyzed by promoter-GUS histochemistry in the primary and secondary xylem tissues from floral stems and roots of Arabidopsis thaliana. Expression patterns indicated that the EgCCR and EgCAD2 genes were expressed in a coordinated manner in primary and secondary xylem tissues of the Arabidopsis floral stem and root. Both genes were expressed in all lignifying cells (vessel elements, xylem fibers and paratracheal parenchyma cells) of xylem tissues. The capacity for long-term monolignol production appeared to be related to the cell-specific developmental processes and biological roles of different cell types. Our results suggested that lignification of short-lived vessel elements was achieved by a two-step process involving (i) monolignol production by vessel elements prior to vessel programmed cell death and (ii) subsequent monolignol production by vessel-associated living paratracheal parenchyma cells following vessel element cell death. EgCCR and EgCAD2 gene expression patterns suggested that the process of xylem cell lignification was similar in both primary and secondary xylem tissues in Arabidopsis floral stems and roots.
Asunto(s)
Oxidorreductasas de Alcohol/biosíntesis , Aldehído Oxidorreductasas/biosíntesis , Arabidopsis , Eucalyptus/enzimología , Proteínas de Plantas/biosíntesis , Xilema/enzimología , Oxidorreductasas de Alcohol/genética , Aldehído Oxidorreductasas/genética , Arabidopsis/citología , Arabidopsis/enzimología , Arabidopsis/genética , Eucalyptus/citología , Eucalyptus/genética , Regulación Enzimológica de la Expresión Génica/genética , Regulación de la Expresión Génica de las Plantas/genética , Proteínas de Plantas/genética , Raíces de Plantas/citología , Raíces de Plantas/enzimología , Raíces de Plantas/genética , Tallos de la Planta/citología , Tallos de la Planta/enzimología , Tallos de la Planta/genética , Plantas Modificadas Genéticamente , Xilema/citología , Xilema/genéticaRESUMEN
An efficient in vitro plant regeneration method was developed for Lycopodiella inundata (L.) Holub, an endangered medicinal Lycopod (Pteridophytes). Vegetative apices were used as explant material. Nodular calluses were established after three cycles (13 weeks each) on a medium containing a few minerals and organic compounds and supplemented with 0.05 µM 3-indolebutyric acid (IBA) and 1.4 µM kinetin (Kin). Propagation was achieved every 13 weeks on this callus medium (CM). When nodular calluses were transferred on a medium supplemented with 2.5 µM IBA and 0.33 µM gibberellic acid (GA(3)) designated as embryogenic medium (EM), organized structures appeared and developed into plantlets. Development phases were characterized by histological studies. Some phases of zygotic embryogenesis previously described for Lycopods were observed in L. inundata. Histological analyses established that an indirect somatic embryo was derived from a single embryogenic cell by following the zygotic developmental pathway. As this phenomenon has not previously been reported in Lycopods, a comparison between somatic and zygotic embryos is discussed based upon morphology and histology.