Gibberellins accumulate in the elongating endodermal cells of Arabidopsis root
ABSTRACT Plant hormones are small-molecule signaling compounds that are collectively involved in all aspects of plant growth and development. Unlike animals, plants actively regulate the spatial distribution of several of their hormones. For example, auxin transport results in the formation of auxin maxima that have a key role in developmental patterning. However, the spatial distribution of the other plant hormones, including gibberellic acid (GA), is largely unknown. To address this, we generated two bioactive fluorescent GA compounds and studied their distribution in Arabidopsis thaliana roots. The labeled GAs specifically accumulated in the endodermal cells of the root elongation zone. Pharmacological studies, along with examination of mutants affected in endodermal specification, indicate that GA accumulation is an active and highly regulated process. Our results strongly suggest the presence of an active GA transport mechanism that would represent an additional level of GA regulation.
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- "The contents of these hormones were dependent on low temperature, and exposure to variable low temperature treatments for 60 days could be used as the critical point for dormancy mediation in lily bulbs 'Siberia' and 'Tiber' (Hua et al., 2011). Chilling exposure of bulbs could lead to the production of growth promoting substances that were gibberellins-like (Shani et al., 2013) and auxin-like (Tsukamoto, 1971), and low temperature treatment promoted the translocation of gibberellins-like and auxin-like substances from the bulb scale to the shoot apex (Rodrigues-Pereira, 1964). Low temperature treatment promoted the breaking of bulb dormancy in L. hansoni, which was in accordance with the results of other studies that showed low temperature affects the carbohydrate contents and plant growth regulators that triggered shoot emergence. "
ABSTRACT: This study was conducted to determine the optimum low temperature treatment and the additive effect of soaking in hot water to overcome bulb dormancy of Hanson lily 'Lilium hansonii'. To accomplish this, bulbs were refrigerated at 1, 4, and 7A degrees C for 35, 50, and 65 days, respectively. As the control treatment, the bulbs were planted directly without any cold or hot water treatment. After the treatments, the bulbs were planted in pots filled with sterilized commercial soil mixture and vermiculite at a depth of about 5-10 cm in a greenhouse. The days to emergence, percentage of emergence, plant height (cm), number of leaves, number of flowers, and days to flowering were recorded. Bulbs soaked in hot water (45A degrees C) for 1 hour and stored at 4A degrees C for 65 days showed the earliest emergence and the maximum emergence percentage. Moreover, storage at 4A degrees C for 65 days (without hot water treatment) was found to promote stalk elongation and a higher number of leaves than the hot water treated bulbs. Results indicated that hot water treatment had a significant additive effect on breaking bulb dormancy in L. hansonii, particularly with respect to days to emergence. Hot water pre-treatment also equilibrated the internal conditions of the bulbs, which resulted in the uniformity of the physiological state of the bulb.Horticulture, Environment and Biotechnology 08/2014; 55(4):257-262. DOI:10.1007/s13580-014-0143-1 · 0.49 Impact Factor
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- "Application of Fl–GA 3 in Arabidopsis roots showed specic GA accumulation patterns in the endodermal cells of the elongation zone. In addition, REPRESSOR OF GA (RGA) marker (GFP:RGA), which encodes a DELLA protein that is degraded in the presence of active GA, showed decreasing signal in the endodermal cells, indicating that GA accumulates in these cells in wild-type plants (Shani et al., 2013). These new experimental approaches could be useful to further investigate a possible role of GA movement in owering time control of Arabidopsis. "
ABSTRACT: Successful plant reproduction relies on the perfect orchestration of singular processes that culminate in the product of reproduction: the seed. The floral transition, floral organ development, and fertilization are well-studied processes and the genetic regulation of the various steps is being increasingly unveiled. Initially, based predominantly on genetic studies, the regulatory pathways were considered to be linear, but recent genome-wide analyses, using high-throughput technologies, have begun to reveal a different scenario. Complex gene regulatory networks underlie these processes, including transcription factors, microRNAs, movable factors, hormones, and chromatin-modifying proteins. Here we review recent progress in understanding the networks that control the major steps in plant reproduction, showing how new advances in experimental and computational technologies have been instrumental. As these recent discoveries were obtained using the model species Arabidopsis thaliana, we will restrict this review to regulatory networks in this important model species. However, more fragmentary information obtained from other species reveals that both the developmental processes and the underlying regulatory networks are largely conserved, making this review also of interest to those studying other plant species.Journal of Experimental Botany 06/2014; DOI:10.1093/jxb/eru233 · 5.79 Impact Factor
- "Thus, cell polarity is crucial from the start to the final stages of plant development. Cell polarity is also important for polar transport processes that induce asymmetric distribution of signaling molecules directing plant development, such as the plant hormones auxin and gibberellin (Grunewald and Friml 2010; Shani et al. 2013). "
Article: Cell Polarity and Development[Show abstract] [Hide abstract]
ABSTRACT: All cells show some degree of polarity, either by asymmetrically distributed membrane or cytosolic components. Even in bacterial cells that do not have the eukaryotic membrane compartmentalization of the cytoplasm, proteins can be localized at specific areas. In rod-shaped bacteria, many processes such as signaling, flagella, and DNA uptake occur at the cell poles.Journal of Integrative Plant Biology 08/2013; 55(9). DOI:10.1111/jipb.12099 · 3.45 Impact Factor