Involvement of hormones and KNOXI genes in early Arabidopsis seedling development

As sessile organisms, plants must sense environmental conditions and adjust their growth and development processes accordingly, through adaptive responses regulated by various internal factors, including hormones. A key environmental factor is temperature, but temperature-sensing mechanisms are not fully understood despite intense research. We investigated proteomic responses to temperature shocks (15 min cold or heat treatments) with and without exogenous applications of cytokinin in Arabidopsis. Image and mass spectrometric analysis of the two-dimensionally separated proteins detected 139 differentially regulated spots, in which 148 proteins were identified, most of which have not been previously linked to temperature perception. More than 70% of the temperature-shock response proteins were modulated by cytokinin, mostly in a similar manner as heat shock. Data mining of previous transcriptomic datasets supported extensive interactions between temperature and cytokinin signalling. The biological significance of this finding was tested by assaying an independent growth response of Arabidopsis seedlings to heat stress: hypocotyl elongation. This response was strongly inhibited in mutants with deficiencies in cytokinin signalling or endogenous cytokinin levels. Thus, cytokinins may directly participate in heat signalling in plants. Finally, large proportions of both temperature-shock and cytokinin responsive proteomes co-localize to the chloroplast, which might therefore host a substantial proportion of the temperature response machinery.

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“…; Souček et al . ) and proteomic responses (Černý et al . ), without causing cytotoxic effects within 15 min of treatment (Mlejnek et al .…”

Section: Resultsmentioning

confidence: 99%

Cytokinin modulates proteomic, transcriptomic and growth responses to temperature shocks in Arabidopsis

Černý

Jedelský

Novák

et al. 2014

Plant Cell & Environment

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“…In addition, high auxin levels down‐regulate the expression of KNOX genes (Shani et al. , 2006), and it has been suggested that KNOX proteins may inhibit the transport of auxin (Soucek et al. , 2007).…”

Section: Introductionmentioning

confidence: 99%

Pluripotency of Arabidopsis xylem pericycle underlies shoot regeneration from root and hypocotyl explants grown in vitro

Atta¹,

Laurens²,

et al. 2009

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SummaryWe have established a detailed framework for the process of shoot regeneration from Arabidopsis root and hypocotyl explants grown in vitro. Using transgenic plant lines in which the GUS or GFP genes were fused to promoters of developmental genes (WUS, CLV1, CLV3, STM, CUC1, PLT1, RCH1, QC25), or to promoters of genes encoding indicators of the auxin response (DR5) or transport (PIN1), cytokinin (CK) response (ARR5) or synthesis (IPT5), or mitotic activity (CYCB1), we showed that regenerated shoots originated directly or indirectly from the pericycle cells adjacent to xylem poles. In addition, shoot regeneration appeared to be partly similar to the formation of lateral root meristems (LRMs). During pre-culture on a 2, 4-dichlorophenoxyacetic acid (2, 4-D)-rich callus-inducing medium (CIM), xylem pericycle reactivation established outgrowths that were not true calli but had many characteristics of LRMs. Transfer to a CK-rich shoot-inducing medium (SIM) resulted in early LRM-like primordia changing to shoot meristems. Direct origin of shoots from the xylem pericycle occurred upon direct culture on CK-containing media without prior growth on CIM. Thus, it appeared that the xylem pericycle is more pluripotent than previously thought. This pluripotency was accompanied by the ability of pericycle derivatives to retain diploidy, even after several rounds of cell division. In contrast, the phloem pericycle did not display such developmental plasticity, and responded to CKs with only periclinal divisions. Such observations reinforce the view that the pericycle is an 'extended meristem' that comprises two types of cell populations. They also suggest that the founder cells for LRM initiation are not initially fully specified for this developmental pathway.

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“…4a). Interestingly, the KNAT1 homeobox transcription factor is expressed at the base of LR primordia (Truernit et al ., 2006) and is auxin‐induced and ABA‐repressed in LR primordia (Soucek et al ., 2007), suggesting a possible point of integration for the two signals. Further research is needed to establish ABA as an inhibitor of LR initiation in Arabidopsis .…”

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Branching out in new directions: the control of root architecture by lateral root formation

Nibau¹,

Gibbs²,

2008

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SummaryPlant roots are required for the acquisition of water and nutrients, for responses to abiotic and biotic signals in the soil, and to anchor the plant in the ground. Controlling plant root architecture is a fundamental part of plant development and evolution, enabling a plant to respond to changing environmental conditions and allowing plants to survive in different ecological niches. Variations in the size, shape and surface area of plant root systems are brought about largely by variations in root branching. Much is known about how root branching is controlled both by intracellular signalling pathays and by environmental signals. Here, we will review this knowledge, with particular emphasis on recent advances in the field that open new and exciting areas of research. I. BackgroundA plant's root system is the site of water and nutrient uptake from the soil, a sensor of abiotic and biotic stresses, and a structural anchor to support the shoot. The root system communicates with the shoot, and the shoot in turn sends signals to the roots. A plant root system initially consists of a primary root (PR) formed during embryogenesis that has dividing cells in a meristem at its tip. As the seedling develops, certain other cells within the PR acquire the capability to *These authors contributed equally to this work.Key words: abiotic stress, biotic stress, lateral root development, nutrients, plant hormones, root system architecture, transcriptomics. (Fig. 1a). These branch out from the PR, greatly increasing the total surface area and mechanical strength of the root system and allow the plant to explore the soil environment. Ultimately, millions of higher-order root branches can form, resulting in hundreds of miles of root system in a small area of soil (Dittmer, 1937). New roots, called adventitious roots (AR), can also be formed postembryonically at the shoot-root junction, optimizing the exploration of the upper soil layers (Fig. 1a). In cereals such as rice and maize, root structure becomes more complex, with the formation of additional shoot-borne and postembryonic roots, which in turn undergo higher-order branching (Hochholdinger et al., 2004; Hochholdinger & Zimmermann, 2008; Fig. 1b). The root system architecture (RSA) of plants varies hugely between species and also shows extensive natural variation within species, reflecting the plethora of environments in which plants can grow (Cannon, 1949;Loudet et al., 2005;Osmont et al., 2007). Root system architecture manipulation is instrumental in the domestication and breeding of crop plants, because using water and nutrients from the soil in the most efficient manner affects a plant's ability to survive in stressful or poor soils. Changes in RSA can therefore have huge impacts on the final yield of a crop (reviewed in de Dorlodot et al., 2007). Of the factors that control total RSA, LR formation and growth is one of the most important.Many of the hormonal and environmental signals affecting LR development also affect other components that have a bearing on RSA...

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Involvement of hormones and KNOXI genes in early Arabidopsis seedling development

Cited by 20 publications

References 58 publications

Cytokinin modulates proteomic, transcriptomic and growth responses to temperature shocks in Arabidopsis

Cytokinin modulates proteomic, transcriptomic and growth responses to temperature shocks in Arabidopsis

Pluripotency of Arabidopsis xylem pericycle underlies shoot regeneration from root and hypocotyl explants grown in vitro

Branching out in new directions: the control of root architecture by lateral root formation

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