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Drawing of Rumex palustris showing the main root types of plants grown in (A) aerated or (B) de-oxygenated stagnant nutrient solution. (C) shows the regions and numbers of adventitious roots formed by plants either in continuously aerated or stagnant de-oxygenated nutrient solution for the final 10 d. Upper tap root = top 1 mm. Data given are means ± standard errors (n ¼ 3).
Source publication
Thirteen alpha-expansin genes were isolated from Rumex palustris , adding to the six already documented for this species. Five alpha-expansin genes were selected for expression studies in various organs/tissues of R. palustris , with a focus on roots exposed to aerated or O2)-deficient conditions, using real-time RT-PCR. Several cases of differenti...
Contexts in source publication
Context 1
... effects of stagnant conditions on the forma- tion of adventitious roots, and porosity in adven- titious, tap, and primary lateral roots, were assessed. Upon transfer to stagnant conditions, new roots emerged from, or above, the root-shoot junction and also from the upper region of the tap root (Figure 2A and 2B). Laan et al. (1989) termed these 'adventitious' and 'secondary lateral' roots, respectively. ...
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In production, shoot cuttings of lavender are most often used for vegetative propagation, however, this method does not promote high propagation rate. The most effective method is propagation by axillary or terminal buds that requires further plant rooting in vitro. Due to, objective of our work was analysis of lavender in vitro rhizogenesis. Inves...
Citations
... hypoxia, nutrient deficiency) by two known mechanisms: lysigeny and schizogeny (Evans, 2003;Visser and Voesenek, 2004). Lysigenous aerenchyma is formed through cell lysis (death) (Haque et al, 2010), while schizogenous aerenchyma is formed by the separation of cells from each other, often accompanied by cell divisions and normal expansion (Jackson and Armstrong, 1999;Colmer et al, 2004). Under submerged conditions, ethylene production is accelerated which in turn stimulates aerenchyma formation in adventitious roots and induces the growth of the roots (Jackson, 1989). ...
Waterlogging, caused by flooding, excessive rains and poor drainage is a serious abiotic stress determining crop productivity worldwide. Maize (Zea mays L) is a basic food grain in many areas and several cultures and is cultivated under much diverse agro-climatic zones extending from subtropical to cooler temperate regions. Therefore, the crop remains open to varied types of biotic as well as abiotic stresses. Among various abiotic stresses, water-logging is one of the most important constraints for maize production and productivity. Breeding for improved wa-terlogging tolerance includes modification of plant morphology, use of tolerant secondary traits and development of resistant varieties through conventional breeding and biotechnological approaches. A successful programme in conventional breeding should involve the integration of several criteria into one selection index and also successful breeding programmes for improved tolerance to submergence stress frequently combine two or more breeding strategies. Marker assisted selection (MAS) is an effective approach to identify genomic regions of crops under stress and construction of molecular linkage maps enable carry out pyramiding of desirable traits to improve sub-mergence tolerance through MAS. Abstract Introduction
... Expansins (EXP) were discovered to expand growing plant cell walls faster at low (acidic) pH than at neutral pH and to influence the structure of cellulose/hemicellulose frameworks. The mRNA levels of expansin genes and expansin protein levels are strongly correlated with the growth and development of root and shoot organs [10,11]. The expression of CaEXPA14 and CaEXPA19 positively correlated with the rate of cell expansion in bell pepper [12]. ...
Background
The Capsicum annuum receptor-like kinase 1 (CaRLK1) gene encodes a transmembrane protein with a cytoplasmic kinase domain and an extracellular domain. It functions as a negative regulator of plant cell death. Ectopic expression of CaRLK1 showed the hypoxia-resistance and enhanced cell division and proliferation. In this study, it was investigated which genes were controlled by ectopic expression of CaRLK1 because it decreased its average cell size of transgenic RLK1ox cells compared with that of wild-type cells (BY-2). ResultsThe average diameter (AD) of the protoplast of RLK1ox cells was about 10 µm shorter than the AD of BY-2 cells. The diameter distribution of the circular protoplasts is mainly from 20 to 40 μm (71.7%) in RLK1ox cells, whereas from 30 to 50 μm (73.0%) in BY-2 cells. Furthermore, cell volume of RLK1ox cells is also 2.5-times smaller than that of BY-2 cells. Smaller cell size of the RLK1ox cells may be related with the inhibited cell expansion because expressions of 12 expansin A genes, 6 expansin-like B genes, 2 ACC synthase genes, and 5 ACC oxidase genes were suppressed, but expressions of 7 gibberellin 2-oxidase genes were induced. The cell walls between two RLK1ox cells are approximately 138.83±4.12 nm thick on average, while those between two BY-2 cells are approximately 156.58±4.54 nm thick. Furthermore, the total content of neutral sugars in the cell wall of RLK1ox cells is less than that of BY-2 cells (about 25%). The RLK1ox cells contained 30% less glucose content than did the BY-2 cells. Thinner cell wall of the RLK1ox cells is related with the decreased cellulose biosynthesis and hemicellulose biosynthesis. Expressions of 7 CESA genes, 5 sucrose synthase 1 genes, 3 mannose-1-phosphate guanyltransferase genes, and 6 glucomannan-4-beta-mannosyltransferase genes were suppressed. The suppressed expressions of 14 polygalacturonase genes may also contribute to make the cell wall of RLK1ox cell thinner than that of BY-2 cell. Conclusion
Of special emphasis is its impact of CaRLK1 gene on cell size control and cell wall thickness. Smaller cell size of the RLK1ox cells correlates with the inhibited cell expansion.
... Considering that the root hair is a growing extension of a single epidermal cell and that root hair growth requires intensive cell wall modification and loosening (Yu et al., 2011) and the idea that expansins might be related with the formation of lateral root primordia (Colmer et al., 2004), it holds water to hypothesize that the modifications that we observed in the roots of NtEXPA11-OX plants were mediated by the overexpressed expansin gene since expansins have been shown and reported to play an important role in this regard. ...
Apart from providing the much-needed strength, plant cell walls define the shape, size and function of cells. As such, there is a constant change in the cell wall dynamics. These are facilitated by various enzymes and proteins. Expansins are a typical example of those cell wall proteins that are involved in cell wall modifications underlying many plant developmental and physiological processes. In this work, we investigated the role of NtEXPA11 gene in tobacco by generating transgenic plants ectopically expressing NtEXPA11 under the control of CaMV35S promoter. Gene expression analysis revealed that although this gene was present in all the studied tissues in WT plants, its transcript levels were highest in the stems, flowers and leaves and lowest in the roots. Following its overexpressing in tobacco, the NtEXPA11 – ox plants exhibited an enhanced growth phenotype. Compared to WT plants, these plants demonstrated an increased growth rate which was characterized by a vigorous root system as well as an accelerated growth rate during their early developmental stages. NtEXPA11 – ox plants also developed significantly bigger leaves and internode lengths. They exhibited a 57% increase (NtEXPA11- 12) and 98% increase (NtEXPA11 line 19) in leaf area when grown on MS media. Most interestingly, NtEXPA11- ox plants had significantly bigger pith and parenchyma cells compared to their WT counterparts. Furthermore, we noted that NtEXPA11 plays an important role in plant adaptation to stresses as indicated by the improved tolerance to drought and salt stress of the NtEXPA11-ox plants compared to the WT plants.
... According to the results of four days of hypoxia (Fig. 4D), the cells were far from a spherical shape, there were relatively large intercellular spaces among the cells, there were no clear boundaries among the adjacent cells and cell walls were thin and destroyed in some cases. In plants, aerenchyma formation in the root cortex enhances root porosity (Colmer et al., 2004), which can lead to increase the diffusion of oxygen from shoots to roots (Colmer et al., 2004). Besides, aerenchyma tissue ventilates excess gases such as ethylene, methane, and carbon dioxide between the roots and the atmosphere. ...
... According to the results of four days of hypoxia (Fig. 4D), the cells were far from a spherical shape, there were relatively large intercellular spaces among the cells, there were no clear boundaries among the adjacent cells and cell walls were thin and destroyed in some cases. In plants, aerenchyma formation in the root cortex enhances root porosity (Colmer et al., 2004), which can lead to increase the diffusion of oxygen from shoots to roots (Colmer et al., 2004). Besides, aerenchyma tissue ventilates excess gases such as ethylene, methane, and carbon dioxide between the roots and the atmosphere. ...
... According to the results of four days of hypoxia (Fig. 4D), the cells were far from a spherical shape, there were relatively large intercellular spaces among the cells, there were no clear boundaries among the adjacent cells and cell walls were thin and destroyed in some cases. In plants, aerenchyma formation in the root cortex enhances root porosity (Colmer et al., 2004), which can lead to increase the diffusion of oxygen from shoots to roots (Colmer et al., 2004). Besides, aerenchyma tissue ventilates excess gases such as ethylene, methane, and carbon dioxide between the roots and the atmosphere. ...
... According to the results of four days of hypoxia (Fig. 4D), the cells were far from a spherical shape, there were relatively large intercellular spaces among the cells, there were no clear boundaries among the adjacent cells and cell walls were thin and destroyed in some cases. In plants, aerenchyma formation in the root cortex enhances root porosity (Colmer et al., 2004), which can lead to increase the diffusion of oxygen from shoots to roots (Colmer et al., 2004). Besides, aerenchyma tissue ventilates excess gases such as ethylene, methane, and carbon dioxide between the roots and the atmosphere. ...
... Here, cell death appears in a predictable pattern and is controlled by a hormone (ethylene); this is an example of programmed cell death [15]. Previous studies have shown that many important crop species, such as maize [16][17][18], rice [19], barley [20], and wheat [21,22], develop lysigenous aerenchyma, whereas schizogenous aerenchyma is formed in some wetland herb species such as Rumex species [23][24][25]. In addition, only a few species, such as Sagittaria lancifolia L., form both lysigenous and schizogenous aerenchyma, which develop in different tissues [26]. ...
Trees growing in wetlands develop adventitious roots from the trunk during the rainy season and adapt to the flooded environment by forming primary (schizogenous or lysigenous) and secondary aerenchyma in the roots. Therefore, it is necessary to clarify the formation process of each type of aerenchyma in these adventitious roots. In this study, saplings of Syzygium kunstleri (King) Bahadur and R.C.Gaur were grown under four different treatments, and a total of 12 adventitious roots generated from trunks were used to clarify the distribution of each aerenchyma type in the roots using light or epi-florescence microscopy. Schizogenous aerenchyma was observed in the root tips where the root color was white or light brown, whereas lysigenous aerenchyma was found at some distance from the root tip where the root color gradually changed from light to dark brown. The secondary aerenchyma and periderm were observed in dark brown parts near the root base. None or only one layer of phellem cells was detected in the white roots near the root tip, but dark brown roots near the root base had at least three layers of phellem cells. Considering these results, oxygen transportation may occur between primary and secondary aerenchyma at the point where two or more layers of phellem cells are formed.
... 11 Under waterlogging conditions, transcript abundance of expansins is associated with cell wall loosening in the elongation zone of the roots. 12 Plasma membrane and cell wall also comprise of structurally complex protein arabinogalactan, which play an important role in signaling events. ...
... Maize CWM genes showed the presence of exons and introns in the genomic sequence. PAE (GRMZM2G156365) had the largest set of introns (12) and exons (13) Five sequence motifs were observed in 12 CWM genes ( Figure 2B). FIMO tool in MEME suite was used to analyze the occurrences of motifs in a set of genes. ...
Cell wall modification (CWM) promotes the formation of aerenchyma in roots under waterlogging conditions as an adaptive mechanism. Lysigenous aerenchyma formation in roots improves oxygen transfer in plants, which highlights the importance of CWM as a focal point in waterlogging stress tolerance. We investigated the structural and functional compositions of CWM genes and their expression patterns under waterlogging conditions in maize. Cell wall modification genes were identified for 3 known waterlogging-responsive cis-acting regulatory elements, namely, GC motif, anaerobic response elements, and G-box, and 2 unnamed elements. Structural motifs mapped in CWM genes were represented in genes regulating waterlogging stress-tolerant pathways, including fermentation, glycolysis, programmed cell death, and reactive oxygen species signaling. The highly aligned regions of characterized and uncharacterized CWM proteins revealed common structural domains amongst them. Membrane spanning regions present in the protein structures revealed transmembrane activity of CWM proteins in the plant cell wall. Cell wall modification proteins had interacted with ethylene-responsive pathway regulating genes (E3 ubiquitin ligases RNG finger and F-box) in a maize protein-protein interaction network. Cell wall modification genes had also coexpressed with energy metabolism, programmed cell death, and reactive oxygen species signaling, regulating genes in a single coexpression cluster. These configurations of CWM genes can be used to modify the protein expression in maize under waterlogging stress condition. Our study established the importance of CWM genes in waterlogging tolerance, and these genes can be used as candidates in introgression breeding and genome editing experiments to impart tolerance in maize hybrids.
... In the present study, we report the formation of permeable cuticle in the aerial organs of hypoxia-stressed Arabidopsis, presumably in order to cope with intracellular hypoxia (Fig. 1). Because there is no currently available evidence that Arabidopsis seedlings form aerenchyma in response to hypoxia, the formation of permeable cuticle may play a similar role (Yu and Patrick 2003;Colmer et al. 2004;Evans 2004;Fukao and Bailey-Serres 2004). ...
Key message
An increased permeability of the cuticle is closely associated with downregulation of genes involved in cuticular lipid synthesis in hypoxia-stressed Arabidopsis and may allow plants to cope with oxygen deficiency.
Abstract
The hydrophobic cuticle layer consisting of cutin polyester and cuticular wax is the first barrier to protect the aerial parts of land plants from environmental stresses. In the present study, we investigated the role of cuticle membrane in Arabidopsis responses to oxygen deficiency. TEM analysis showed that the epidermal cells of hypoxia-treated Arabidopsis stems and leaves possessed a thinner electron-translucent cuticle proper and a more electron-dense cuticular layer. A reduction in epicuticular wax crystal deposition was observed in SEM images of hypoxia-treated Arabidopsis stem compared with normoxic control. Cuticular transpiration was more rapid in hypoxia-stressed leaves than in normoxic control. Total wax and cutin loads decreased by approximately 6–12 and 12–22%, respectively, and the levels of C29 alkanes, secondary alcohols, and ketones, C16:0 ω-hydroxy fatty acids, and C18:2 dicarboxylic acids were also prominently reduced in hypoxia-stressed Arabidopsis leaves and/or stems relative to normoxic control. Genome-wide transcriptome and quantitative RT-PCR analyses revealed that the expression of several genes involved in the biosynthesis and transport of cuticular waxes and cutin monomers were downregulated more than fourfold, but no significant alterations were detected in the transcript levels of fatty acid biosynthetic genes, BCCP2, PDH-E1α, and ENR1 in hypoxia-treated Arabidopsis stems and leaves compared with normoxic control. Taken together, an increased permeability of the cuticle is closely associated with downregulation of genes involved in cuticular lipid synthesis in hypoxia-stressed Arabidopsis. The present study elucidates one of the cuticle-related adaptive responses that may allow plants to cope with low oxygen levels.
... The treatment solution contained 10 mM KCl, 5 mM Ca 2+ -MES, pH 6.1, and 0.2% (w/v) agar which was dissolved by boiling while being stirred, and the solution was cooled down to room temperature, and then bubbled with high purity N 2 .The whole seedlings were submerged in agar solution in a transparent container and were exposed to 16 h/8 h light/dark cycles, enabling plant photosynthetic activity; this approach was taken following earlier work on Arabidopsis (Mustroph et al., 2009). The addition of agar prevents convective movements in the solution and so impedes re-entry of any O 2 during the treatment period (Colmer et al., 2004). For confocal imaging of K + , Ca 2+ , superoxide, and H 2 O 2 distribution in roots, the WT and two mutants were subjected to hypoxic treatment for 1, 24, and 72 h. ...
Regulation of root cell K⁺ is essential for acclimation to low oxygen stress. The potential roles of GORK (depolarization-activated guard cell outward-rectifying potassium) channels and RBOHD (respiratory burst oxidase homologue D) in plant adaptive responses to hypoxia were investigated in the context of tissue specificity (epidermis versus stele; elongation versus mature zone) in roots of Arabidopsis. The expression of GORK and RBOHD was down-regulated by 2- to 3-fold within 1 h and 24 h of hypoxia treatment in Arabidopsis wild-type (WT) roots. Interestingly, a loss of the functional GORK channel resulted in a waterlogging-tolerant phenotype, while rbohD knockout was sensitive to waterlogging. To understand their functions under hypoxia stress, we studied K⁺, Ca²⁺, and reactive oxygen species (ROS) distribution in various root cell types. gork1-1 plants had better K⁺ retention ability in both the elongation and mature zone compared with the WT and rbohD under hypoxia. Hypoxia induced a Ca²⁺ increase in each cell type after 72 h, and the increase was much less pronounced in rbohD than in the WT. In most tissues except the elongation zone in rbohD, the H2O2 concentration had decreased after 1 h of hypoxia, but then increased significantly after 24 h of hypoxia in each zone and tissue, further suggesting that RBOHD may shape hypoxia-specific Ca²⁺ signatures via the modulation of apoplastic H2O2 production. Taken together, our data suggest that plants lacking functional GORK channels are more capable of retaining K⁺ for their better performance under hypoxia, and that RBOHD is crucial in hypoxia-induced Ca²⁺ signalling for stress sensing and acclimation mechanism. © The Author 2017. Published by Oxford University Press on behalf of the Society for Experimental Biology.
... This occurs due to the increase in the synthesis of ethylene caused by increased activity of ACC synthase, resulting in increased cellulase activity, which in turn contributes to degradation of the cell wall and formation of aerenchyma (Takahashi et al. 2014). There is a second type, the schizogenous aerenchyma, originating from the connection of cells, which form continuous columns for the storage and transport of gases (Joly 1991; Colmer et al. 2004 ). Furthermore, adventitious roots to capture and transport oxygen to the submerged tissues can be developed (Dias-Filho 2012). ...
The diversification of forage grasses is a strategic solution to obtain higher productivity in diverse environments. In this regard, the objective of the present study was to evaluate in a glasshouse study the flooding tolerance of 9 cultivars of forage grasses. The study was conducted using a complete randomized design with a 9 x 3 factorial arrangement: 9 cultivars (Brachiaria brizantha cvv. Marandu, Piatã e Xaraés; hybrid Brachiaria cv. Mulato II; B. humidicola cvv. Llanero and Tupi; B. ruziziensis cv. Common; Panicum maximum cvv. Massai and Tanzânia) and 3 soil water levels: a) minimal water for development (50% of field capacity); b) field capacity; and c) flooded soil (2 cm above soil level), with 3 replicates. Forage accumulation, plant height and root accumulation were evaluated. All cultivars grew well in soil at 50% field capacity highlighting their adaptation to mildly dry conditions. Under flooded conditions, B. humidicola cvv. Llanero and Tupi showed no reduction in forage dry matter production, while shoot growth of cvv. Marandu, Piatã, Tanzânia and Xaraés was significantly reduced (P<0.001) by 71.3, 94.0, 81.2 and 77.2%, respectively. Root mass was reduced about 30% in flooded plants relative to those grown at 50% field capacity. While all cultivars could be used where soil moisture is marginal for production, cvv. Llanero, Tupi and Massai would be most suitable where flooding could occur during the growing season. Field studies are needed to verify these glasshouse findings.Keywords: Brachiaria spp., forage mass, Marandu Death Syndrome, Panicum maximum, root mass, soil water levels.DOI: 10.17138/TGFT(4)1-7
