The uptake and the transport of14C-labeled epibrassinolide in intact seedlings of cucumber and wheat

Nishikawa, Naoko; Toyama, Shigehiro; Shida, Atsuhiko; Futatsuya, Fumio

doi:10.1007/bf02346007

Cited by 31 publications

(17 citation statements)

References 9 publications

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“…Similarly, when 14 C-epiBL was applied to the roots of cucumber and wheat seedlings, 14 C was soon detected throughout both plant species (Nishikawa et al, 1994). However, in this case, it is not clear if the 14 C detected was 14 C-epiBL itself or a labeled metabolite of 14 C-epiBL.…”

Section: Brs Do Not Undergo Long-distance Transport Between the Shootmentioning

confidence: 89%

“…Similar results were obtained when 3 H-CS was applied to the apical bud and when 3 H-BL was applied to either leaves or the apical bud (data not shown). applied 14 C-epiBL was not transported from the treated leaf even after 7 d (Nishikawa et al, 1994).…”

Section: Transport Of Exogenously Applied Radiolabeled Brsmentioning

confidence: 89%

“…Indeed, in the current study, the grafting results provide no evidence for the acropetal transport of BRs from root to shoot in pea and clearly show that BR levels in the shoot are not dependent on BR transport from the roots in this species. Thus, unless grafting disrupts normal BR transport pathways or there are dramatic species-specific differences in the transport of BRs in plants, it is possible that the movement of exogenously applied BRs from the root (Yokota et al, 1992;Nishikawa et al, 1994) may not accurately reflect the transport of endogenous BRs in plants.…”

Section: Brs Do Not Undergo Long-distance Transport Between the Shootmentioning

confidence: 99%

“…Similarly, when 14 C-epiBL was applied to the roots of cucumber (Cucumis sativus) and wheat (Triticum aestivum) seedlings, 14 C was soon detected throughout both plant species (Nishikawa et al, 1994). Markovic-Housley et al (2003) recently proposed a mechanism for the transport of BRs.…”

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confidence: 99%

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Brassinosteroids Do Not Undergo Long-Distance Transport in Pea. Implications for the Regulation of Endogenous Brassinosteroid Levels

2004

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It is widely accepted that brassinosteroids (BRs) are important regulators of plant growth and development. However, in comparison to the other classical plant hormones, such as auxin, relatively little is known about BR transport and its potential role in the regulation of endogenous BR levels in plants. Here, we show that end-pathway BRs in pea (Pisum sativum) occur in a wide range of plant tissues, with the greatest accumulation of these substances generally occurring in the young, actively growing tissues, such as the apical bud and young internodes. However, despite the widespread distribution of BRs throughout the plant, we found no evidence of long-distance transport of these substances between different plant tissues. For instance, we show that the maintenance of steady-state BR levels in the stem does not depend on their transport from the apical bud or mature leaves. Similarly, reciprocal grafting between the wild type and the BR-deficient lkb mutants demonstrates that the maintenance of steady-state BR levels in whole shoots and roots does not depend on either basipetal or acropetal transport of BRs between these tissues. Together, with results from 3 H-BR feeding studies, these results demonstrate that BRs do not undergo long-distance transport in pea. The widespread distribution of end-pathway BRs and the absence of long-distance BR transport between different plant tissues provide significant insight into the mechanisms that regulate BR homeostasis in plants.Brassinosteroids (BRs) are steroidal plant hormones, which are essential for normal plant growth and development. Extensive research over the past two decades has revealed the importance of BRs in a wide variety of processes, including cell elongation, cell division, vascular differentiation, reproductive development, and pathogen and abiotic tolerance (Clouse, 2002). As a consequence, BRs are now widely recognized as an important class of plant growth regulators, alongside the classical plant hormones, such as auxin, GA, cytokinin, abscisic acid (ABA), and ethylene (Clouse, 2002).The importance of BRs in such a diverse range of developmental processes implies the existence of mechanisms that strictly control the endogenous BR levels and their distribution in the target cells or tissues. It is widely accepted that the hormone level at any given site might be affected by the relative rates of its synthesis, destruction, inactivation, and transport within the plant. Each of these factors can be considered in terms of their input to, or output from, the level of free hormone (Bandurski et al., 1995). Inputs into the free hormone pool in a given tissue include de novo synthesis, conjugate hydrolysis, and transport from one site in the plant to another site. Outputs from the free hormone pool include catabolism, conjugate synthesis, and transport away from a given site (Bandurski et al., 1995). It is the coordinated regulation of these processes that determines the endogenous levels of bioactive BRs, which, when coupled with the regulation of BR re...

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Section: Brs Do Not Undergo Long-distance Transport Between the Shootmentioning

confidence: 89%

Section: Transport Of Exogenously Applied Radiolabeled Brsmentioning

confidence: 89%

Section: Brs Do Not Undergo Long-distance Transport Between the Shootmentioning

confidence: 99%

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confidence: 99%

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Brassinosteroids Do Not Undergo Long-Distance Transport in Pea. Implications for the Regulation of Endogenous Brassinosteroid Levels

2004

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“…The efffect of BR on leaf blade-elongation was striking at a high concentration (2 X IQ-6 M). This may be because BRS are hardly absorbed (Nishikawa et al, 1994), difficult to move (Nishikawa et al, 1996) and rapidly metabolized in plants (Yokota, 1992).…”

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confidence: 99%