Gibberellins accumulate in the elongating endodermal cells of Arabidopsis root

Section of Cell and Developmental Biology, Departments of Pharmacology and Chemistry and Biochemistry, and Howard Hughes Medical Institute, University of California at San Diego, La Jolla, CA 92093.
Proceedings of the National Academy of Sciences (Impact Factor: 9.67). 02/2013; 110(12). DOI: 10.1073/pnas.1300436110
Source: PubMed


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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    • "These data indicate that disruption of NtBPL may significantly affect GA biogenesis which may play a significant role in tobacco pedicel development. This is consistent with GA as a key hormone for plant cell elongation and division (Shani et al., 2013). "
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    ABSTRACT: Optimal inflorescence architecture is important for plant reproductive success by affecting the ultimate number of flowers that set fruits and for plant competitiveness when interacting with biotic or abiotic conditions. The pedicel is one of the key contributors to inflorescence architecture diversity. To date, knowledge about the molecular mechanisms of pedicel development is derived from Arabidopsis. Not much is known regarding other plants. Here, an SVP family MADS-box gene, NtSVP, in tobacco (Nicotiana tabacum) that is required for pedicel elongation was identified. It is shown that knockdown of NtSVP by RNA interference (RNAi) caused elongated pedicels, while overexpression resulted in compact inflorescences with much shortened pedicels. Moreover, an Arabidopsis BREVIPEDECELLUS/KNAT1 homologue NtBP-Like (NtBPL) was significantly up-regulated in NtSVP-RNAi plants. Disruption of NtBPL decreased pedicel lengths and shortened cortex cells. Consistent with the presence of a CArG-box at the NtBPL promoter, the direct binding of NtSVP to the NtBPL promoter was demonstrated by yeast one-hybrid assay, electrophoretic mobility shift assay, and dual-luciferase assay, in which NtSVP may act as a repressor of NtBPL. Microarray analysis showed that down-regulation of NtBPL resulted in differential expression of genes associated with a number of hormone biogenesis and signalling genes such as those for auxin and gibberellin. These findings together suggest the function of a MADS-box transcription factor in plant pedicel development, probably via negative regulation of a BP-like class I KNOX gene. The present work thus postulates the conservation and divergence of the molecular regulatory pathways underlying the development of plant inflorescence architecture. © The Author 2015. Published by Oxford University Press on behalf of the Society for Experimental Biology.
    Journal of Experimental Botany 07/2015; DOI:10.1093/jxb/erv332 · 5.53 Impact Factor
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    • "GAs), another class of plant hormones, may also have endodermis-specific roles in controlling root development and AM colonization. In Arabidopsis, fluorescently labeled GA derivatives predominantly accumulate in elongating endodermal cells in the root (Shani et al., 2013 "
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    ABSTRACT: The root endodermis is characterized by the Casparian strip and by the suberin lamellae, two hydrophobic barriers that restrict the free diffusion of molecules between the inner cell layers of the root and the outer environment. The presence of these barriers and the position of the endodermis between the inner and outer parts of the root require that communication between these two domains acts through the endodermis. Recent work on hormone signaling, propagation of calcium waves, and plant-fungal symbiosis has provided evidence in support of the hypothesis that the endodermis acts as a signaling center. The endodermis is also a unique mechanical barrier to organogenesis, which must be overcome through chemical and mechanical crosstalk between cell layers to allow for development of new lateral organs while maintaining its barrier functions. In this review, we discuss recent findings regarding these two important aspects of the endodermis.
    Plant physiology 08/2014; 166(2). DOI:10.1104/pp.114.244871 · 6.84 Impact Factor
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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. "
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    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 · 0.73 Impact Factor
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