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Effect of auxin on root development in transgenic Arabidopsis plants. (A) Effect of IAA (10−9 or 10−7 M) on growth of primary roots in transgenic plants of Arabidopsis. The transgenic plants treated with IAA affected primary root growth compared with wild-type plants. (B) Effect of IAA (10−9 or 10−7 M) on lateral root in transgenic Arabidopsis plant. Results are presented as average values±SE from three experiments. More than ten roots were used in each experiment. Asterisk indicates significant difference P
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Of the diverse abiotic stresses, low temperature is one of the major limiting factors that lead to a series of morphological,
physiological, biochemical, and molecular changes in plants. Ran, an evolutionarily conserved small G-protein family, has
been shown to be essential for the nuclear translocation of proteins. It also mediates the regulation...
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Context 1
... showed a similar phenotype, such as greatly reduced number of lateral roots and stunted primary roots. The number of lat- eral roots was only 4.4 per plant on average in the transgenic seedlings. In contrast, the wild type showed 10.1 per plant under the same condition. Exogenous applications of IAA addressed the phenotype of fewer lateral roots (Fig. 4). These results demonstrated that OsRAN1 controls development of shoots and the roots probably by affecting IAA signalling in the transgenic ...
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... auxin mutants ( Berleth et al., 2000). We tested whether OsRAN1 transgenic Arabidopsis root development defects were affected by auxin by supplementing the growth medium with exogenous IAA The results indicate that IAA typically pro- motes the lateral root initiation but have no obvious effects on primary root length in transgenic Arabidopsis (Fig. 4). In the auxin-signalling pathways, suppressors of auxin action block the expression of auxin-induced genes in the nucleus (Ulmasov et al., 1999). Ran proteins play an important role in nuclear transport. Overexpression of OsRAN1 protein might result in an abnormal or reduced rate of transport of important protein modulators to the ...
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Improved drought tolerance is always a highly desired trait for agricultural plants. Significantly increased drought tolerance in Arabidopsis thaliana (Columbia-0) has been achieved in our work through the suppression of ESKMO1 (ESK1) gene expression with small-interfering RNA (siRNA) and overexpression of CBF genes with constitutive gene expressio...
Aims Root hydrotropism is a response to water-potential gradients that makes roots bend towards areas of higher water potential. The gene MIZU-KUSSEI1 (MIZ1) that is essential for hydrotropism in Arabidopsis roots has previously been identified. However, the role of root hydrotropism in plant growth and survival under natural conditions has not yet...
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... Meanwhile, endogenous auxin levels are associated with cold tolerance by modulating auxin-regulated gravitropism in the rice root tips under cold stress (Du et al. 2012(Du et al. , 2013. OsRAN1 and OsRAN2, two small G-protein family genes, maintain cell division in root apical meristems of rice seedlings via auxin signaling under cold stress (Chen et al. 2011;Xu and Cai 2014). In addition, OsOFP6 controls cold response in roots via an auxin-dependent pathway (Ma et al. 2017). ...
Low-temperature sensitivity at the germination stage is a challenge for direct seeding of rice in Asian countries. How Ca2+ and IAA signaling regulate primary root growth under chilling remains unexplored. Here, we showed that OsCML16 interacted specifically with OsPILS7a to improve primary root elongation of early rice seedlings under chilling. OsCML16, a subgroup 6c member of the OsCML family, interacted with multiple cytosolic loop regions of OsPILS7a in a Ca2+-dependent manner. OsPILS7a localized to the ER membranes and functioned as an auxin efflux carrier in a yeast growth assay. Transgenics showed that presence of OsCML16 enhanced primary root elongation under chilling, whereas the ospils7a knockout mutant lines showed the opposite phenotype. Moreover, under chilling conditions, OsCML16 and OsPILS7a mediated Ca2+ and IAA signaling and regulated the transcription of IAA signaling-associated genes (OsIAA11, OsIAA23, and OsARF16) and cell division marker genes (OsRAN1, OsRAN2, and OsLTG1) in primary roots. These results show that OsCML16 and OsPILS7a cooperatively regulate primary root elongation of early rice seedlings under chilling. These findings enhance our understanding of the crosstalk between Ca2+ and IAA signaling and reveal insights into the mechanisms underlying cold-stress response during rice germination.
... A close association between Ran and plant responses to environmental stresses, such as salinity [39], osmotic stress [8], drought [7], low temperatures [9,40], aluminum toxicity [41], and oxidative stress [11], has been elucidated in numerous studies. However, the understanding of the underlying mechanisms is slowly improving, and there have been rare reports about the role of longan Ran in defense responses. ...
... The data for phenotype analysis were acquired from a minimum of fifteen independent plants. The tobacco root tips were stained by propidium iodide as described previously and observed by laser scanning confocal microscopy (Olympus, Tokyo, Japan; FV1200) [40]. ...
Ran GTPases play essential roles in plant growth and development. Our previous studies revealed the nuclear localization of DlRan3A and DlRan3B proteins and proposed their functional redundancy and distinction in Dimocarpus longan somatic embryogenesis, hormone, and abiotic stress responses. To further explore the possible roles of DlRan3A and DlRan3B, gene expression analysis by qPCR showed that their transcripts were both more abundant in the early embryo and pulp in longan. Heterologous expression of DlRan3A driven by its own previously cloned promoter led to stunted growth, increased root hair density, abnormal fruits, bigger seeds, and enhanced abiotic stress tolerance. Conversely, constitutive promoter CaMV 35S (35S)-driven expression of DlRan3A, 35S, or DlRan3B promoter-controlled expression of DlRan3B did not induce the alterations in growth phenotype, while they rendered different hypersensitivities to abiotic stresses. Based on the transcriptome profiling of longan Ran overexpression in tobacco plants, we propose new mechanisms of the Ran-mediated regulation of genes associated with cell wall biosynthesis and expansion. Also, the transgenic plants expressing DlRan3A or DlRan3B genes controlled by 35S or by their own promoter all exhibited altered mRNA levels of stress-related and transcription factor genes. Moreover, DlRan3A overexpressors were more tolerant to salinity, osmotic, and heat stresses, accompanied by upregulation of oxidation-related genes, possibly involving the Ran-RBOH-CIPK network. Analysis of a subset of selected genes from the Ran transcriptome identified possible cold stress-related roles of brassinosteroid (BR)-responsive genes. The marked presence of genes related to cell wall biosynthesis and expansion, hormone, and defense responses highlighted their close regulatory association with Ran.
... Ran is a small GTPase that involves various developments like nuclear assembly and cell-cycle control [189]. The levels of mRNA encoding OsRAN1 were greatly increased by chilling, and OsRAN1 overexpression in Arabidopsis increased tiller numbers [162]. Elevated expression of miR393 also improves chilling tolerance and tillering [190]. ...
Shoot branching is a complex and tightly regulated developmental process that is essential for determining plant architecture and crop yields. The outgrowth of tiller buds is a crucial step in shoot branching, and it is influenced by a variety of internal and external cues. This review provides an extensive overview of the genetic, plant hormonal, and environmental factors that regulate shoot branching in several plant species, including rice, Arabidopsis, tomato, and wheat. We especially highlight the central role of TEOSINTE BRANCHED 1 (TB1), a key gene in orchestrating bud outgrowth. In addition, we discuss how the phytohormones cytokinins, strigolactones, and auxin interact to regulate tillering/branching. We also shed light on the involvement of sugar, an integral component of plant development, which can impact bud outgrowth in both trophic and signaling ways. Finally, we emphasize the substantial influence of environmental factors, such as light, temperature, water availability, biotic stresses, and nutrients, on shoot branching. In summary, this review offers a comprehensive evaluation of the multifaced regulatory mechanisms that underpin shoot branching and highlights the adaptable nature of plants to survive and persist in fluctuating environmental conditions.
... These results suggested the importance of normal ribosome synthesis for adapting to low-temperature stress. In addition, numerous genes involved in the cell cycle were considered to be closely associated with low-temperature responses in many plants, such as maize [37] and rice [36,57]. In this study, we identified a significant module, MEbrown, using WGCNA analysis, which was highly correlated with Ye478 at the low-temperature germination stage and CAT and SOD activity. ...
Low-temperature germination ability (LTGA) is an important characteristic for spring sowing maize. However, few maize genes related to LTGA were confirmed, and the regulatory mechanism is less clear. Here, maize-inbred lines Ye478 and Q1 with different LTGA were used to perform transcriptome analysis at multiple low-temperature germination stages, and a co-expression network was constructed by weighted gene co-expression network analysis (WGCNA). Data analysis showed that 7964 up- and 5010 down-regulated differentially expressed genes (DEGs) of Ye478 were identified at low-temperature germination stages, while 6060 up- and 2653 down-regulated DEGs of Q1 were identified. Gene ontology (GO) enrichment analysis revealed that ribosome synthesis and hydrogen peroxide metabolism were enhanced and mRNA metabolism was weakened under low-temperature stress for Ye478, while hydrogen peroxide metabolism was enhanced and mRNA metabolism was weakened for Q1. DEGs pairwise comparisons between the two genotypes found that Ye478 performed more ribosome synthesis at low temperatures compared with Q1. WGCNA analysis based on 24 transcriptomes identified 16 co-expressed modules. Of these, the MEbrown module was highly correlated with Ye478 at low-temperature stages and catalase and superoxide dismutase activity, and the MEred, MEgreen, and MEblack modules were highly correlated with Ye478 across low-temperature stages, which revealed a significant association between LTGA and these modules. GO enrichment analysis showed the MEbrown and MEred modules mainly functioned in ribosome synthesis and cell cycle, respectively. In addition, we conducted quantitative trait loci (QTL) analysis based on a doubled haploid (DH) population constructed by Ye478 and Q1 and identified a major QTL explanting 20.6% of phenotype variance on chromosome 1. In this QTL interval, we found three, four, and three hub genes in the MEbrown, MEred, and MEgreen modules, of which two hub genes (Zm00001d031951, Zm00001d031953) related to glutathione metabolism and one hub gene (Zm00001d031617) related to oxidoreductase activity could be the candidate genes for LTGA. These biological functions and candidate genes will be helpful in understanding the regulatory mechanism of LTGA and the directional improvement of maize varieties for LTGA.
... Transcriptome studies have also revealed drought enrichment of GTPases in maize ovary tissues with respect to drought induced splicing (Kakumanu et al., 2012), regulating of stomatal opening , conferring maximum ABA sensitivity (Lee and Seo, 2019) in Arabidopsis, found to trigger innate immunity in rice (Kawano et al., 2010). When Ran GTPase was overexpressed in Arabidopsis and Rice, the transgenic plants showed distinct phenotypes like increased number of tillers, weak apical dominance, excess rosette leaves and abnormal root growth suggesting the involvement of RAN GTPase in cell proliferation (Wang et al., 2006;Xu and Cai, 2014);. A transgenic approach demonstrated that plants overexpressing RAN genes had enhanced cold (Xu et al., 2016) and osmotic stress tolerance (Akashi et al., 2016a) as transgenic plants maintained cell division under stress conditions. ...
Climate change has escalated the effect of drought on crop production as it has negatively altered the environmental condition. Wild watermelon grows abundantly in the Kgalagadi desert even though the environment is characterized by minimal rainfall, high temperatures and intense sunshine during growing season. This area is also characterized by sandy soils with low water holding capacity, thus bringing about drought stress. Drought stress affects crop productivity through its effects on development and physiological functions as dictated by molecular responses. Not only one or two physiological process or genes are responsible for drought tolerance, but a combination of various factors do work together to aid crop tolerance mechanism. Various studies have shown that wild watermelon possess superior qualities that aid its survival in unfavorable conditions. These mechanisms include resilient root growth, timely stomatal closure, chlorophyll fluorescence quenching under water deficit as key physiological responses. At biochemical and molecular level, the crop responds through citrulline accumulation and expression of genes associated with drought tolerance in this species and other plants. Previous salinity stress studies involving other plants have identified citrulline accumulation and expression of some of these genes (chloroplast APX, Type-2 metallothionein), to be associated with tolerance. Emerging evidence indicates that the upstream of functional genes are the transcription factor that regulates drought and salinity stress responses as well as adaptation. In this review we discuss the drought tolerance mechanisms in watermelons and some of its common indicators to salinity at physiological, biochemical and molecular level.
... AtRan1 GTPase boosts abiotic stress tolerance by maintaining the nuclear envelop during chilling stress (Xu et al. 2016). In Oryza sativa, OsRan1 and OsRan2 GTPases have been reported to improve chilling tolerance (Chen et al. 2011;Xu and Cai 2014). The straw mushroom, Volvariella volvacea, possesses the VvRan1 gene whose transcription level has been found to be elevated during cold stress and in the presence of hydrogen peroxide (H 2 O 2 ) (Yan et al. 2016). ...
Plants are frequently subjected to abiotic and biotic stress which causes major impediments in their growth and development. It is emerging that small guanosine triphosphatases (small GTPases), also known as monomeric GTP-binding proteins, assist plants in managing environmental stress. Small GTPases function as tightly regulated molecular switches that get activated with the aid of guanosine triphosphate (GTP) and deactivated by the subsequent hydrolysis of GTP to guanosine diphosphate (GDP). All small GTPases except Rat sarcoma (Ras) are found in plants, including Ras-like in brain (Rab), Rho of plant (Rop), ADP-ribosylation factor (Arf) and Ras-like nuclear (Ran). The members of small GTPases in plants interact with several downstream effectors to counteract the negative effects of environmental stress and disease-causing pathogens. In this review, we describe processes of stress alleviation by developing pathways involving several small GTPases and their associated proteins which are important for neutralizing fungal infections, stomatal regulation, and activation of abiotic stress-tolerant genes in plants. Previous reviews on small GTPases in plants were primarily focused on Rab GTPases, abiotic stress, and membrane trafficking, whereas this review seeks to improve our understanding of the role of all small GTPases in plants as well as their interactome in regulating mechanisms to combat abiotic and biotic stress. This review brings to the attention of scientists recent research on small GTPases so that they can employ genome editing tools to precisely engineer economically important plants through the overexpression/knock-out/knock-in of stress-related small GTPase genes.
... All these information indicated that DXWR probably had superior disease-resistance and starch synthesis ability. Like other stress-responsive traits, the cold resistance characteristics of plants are affected by multiple factors and are also controlled by genetics (Xu and Cai, 2014;Fang et al., 2017). As we know, cold resistance is related to the content of unsaturated fatty acids in plants. ...
Dongxiang wild rice (DXWR, Oryza rufipogon Griff.) belongs to common wild rice O. rufipogon, which is the well-known ancestral progenitor of cultivated rice, possessing important gene resources for rice breeding. However, the distribution of DXWR is decreasing rapidly, and no reference genome has been published to date. In this study, we constructed a chromosome-level reference genome of DXWR by Oxford Nanopore Technology (ONT) and High-through chromosome conformation capture (Hi-C). A total of 58.41 Gb clean data from ONT were de novo assembled into 231 contigs with the total length of 413.46 Mb and N50 length of 5.18 Mb. These contigs were clustered and ordered into 12 pseudo-chromosomes covering about 97.39% assembly with Hi-C data, with a scaffold N50 length of 33.47 Mb. Moreover, 54.10% of the genome sequences were identified as repeat sequences. 33,862 (94.21%) genes were functionally annotated from a total of predicted 35,942 protein-coding sequences. Compared with other species of Oryza genus, the genes related to disease and cold resistance in DXWR had undergone a large-scale expansion, which may be one of the reasons for the stronger disease resistance and cold resistance of DXWR. Comparative transcriptome analysis also determined a list of differentially expressed genes under normal and cold treatment, which supported DXWR as a cold-tolerant variety. The collinearity between DXWR and cultivated rice was high, but there were still some significant structural variations, including a specific inversion on chromosome 11, which may be related to the differentiation of DXWR. The high-quality chromosome-level reference genome of DXWR assembled in this study will become a valuable resource for rice molecular breeding and genetic research in the future.
... Co-related to this observation, the overexpression of rice (Oryza sativa) RAN1 and wheat RAN1 altered auxin sensitivity and mitotic progression, indicating active involvement of RAN1 in the regulation of cold resistance, root growth, reduced apical dominance, and flowering (Wang et al., 2006b;Xu and Cai, 2014). In addition to these observations, the ectopic expression of rice RAN2 rendered transgenic plants hypersensitive to salinity and osmotic stress (Zang et al., 2010). ...
Leaf senescence is the final stage of leaf development and can be triggered by various external factors, such as hormones and light deprivation. In this study, we demonstrate that overexpression of the GTP-bound form of Arabidopsis (Arabidopsis thaliana) Ran1 (a Ras-related nuclear small G-protein, AtRan1) efficiently promotes age-dependent and dark-triggered leaf senescence, while Ran-GDP has the opposite effect. Transcriptome analysis comparing AtRan1-GDP- and AtRan1-GTP-overexpressing transgenic plants (Ran1T27Nox and Ran1G22Vox, respectively) revealed that differentially expressed genes (DEGs) related to the senescence-promoting hormones salicylic acid (SA), jasmonic acid, abscisic acid, and ethylene were significantly up-regulated in dark-triggered senescing leaves of Ran1G22Vox, indicating that these hormones are actively involved in Ran-GTP/-GDP-dependent, dark-triggered leaf senescence. Bioinformatic analysis of the promoter regions of DEGs identified diverse consensus motifs, including the bZIP motif, a common binding site for TGACG-BINDING FACTOR (TGA) transcription factors. Interestingly, TGA2 and its interactor, NONEXPRESSOR OF PATHOGENESIS-RELATED GENES1 (NPR1), which are two positive transcriptional regulators of SA signaling, differed in their extent of accumulation in the nucleus versus cytoplasm of Ran1T27Nox and Ran1G22Vox plants. Moreover, SA-induced, Ran-GTP-/-GDP-dependent functions of NPR1 included genome-wide global transcriptional reprogramming of genes involved in cell death, aging, and chloroplast organization. Furthermore, expression of AtRan1-GTP in SA signaling-defective npr1 and SA biosynthesis-deficient SA-induction deficient2 genetic backgrounds abolished the effects of AtRan1-GTP, thus retarding age-promoted leaf senescence. However, ethylene-induced leaf senescence was not mediated by Ran machinery-dependent nuclear shuttling of ETHYLENE-INSENSITIVE3 and ETHYLENE-INSENSITIVE3-LIKE1 proteins. We conclude that Ran-GTP/-GDP-dependent nuclear accumulation of NPR1 and TGA2 represents another regulatory node for SA-induced leaf senescence.
... In recent decades, numerous genes have been identified as participating in overcoming the adverse impact of low temperature on seed germination. These genes were majorly associated with membrane function and cell cycle regulation [8][9][10][11][12]. ...
Maize originated from tropical regions and is extremely sensitive to low temperature during germination. Our previous work identified a major QTL, qp1ER1-1, for low temperature germination ability (LTGA) of maize. Here, we introgressed qp1ER1-1 from the tolerant line L220 into the sensitive line PH4CV to generate two near isogenic lines NIL220-3 and NIL220-25. When germinated under cold temperature for 25 days (Cold-25), the NILs showed similar seedling root length and shoot length to L220, but significantly higher than PH4CV. However, when germinated under cold temperature for 15 days (Cold-15) or under normal temperature (25 °C) for 3 days (CK-3), all lines showed similar seedling performance, indicating that introgression of qp1ER1-1 from L220 into PH4CV could improve LTGA of NIL220-3 and NIL220-25. The whole seedlings, including root and shoot, of Cold-15 and CK-3 were harvested for transcriptome analysis, when both stayed at a similar developmental stage. Dry seed embryo was sequenced as a non-germination control (CK-0). Compared with PH4CV, the tolerant line (L220, NIL220-3, and NIL220-25) specifically expressed genes (different expressed genes, DEGs) were identified for CK-0, Cold-15, and CK-3. Then, DEGs identified from Cold-15, but not from CK-0 or CK-3, were defined as tolerant line specifically expressed LTGA genes. Finally, 1786, 174, and 133 DEGs were identified as L220, NIL220-3, and NIL220-25 specifically expressed LTGA genes, respectively. Of them, 27 were common LTGA genes that could be identified from all three tolerant lines, with two (Zm00001d031209 and Zm00001d031292) locating in the confidence interval of qp1ER1-1. In addition, GO analysis revealed that L220 specifically expressed LTGA genes were majorly enriched in the cell division process and plasma membrane related categories. Taken together, these results provided new insight into the molecular mechanism of maize seed LTGA and facilitated the cloning of the qp1ER1-1 gene.
... As a crop that originated from the tropical and subtropical areas, rice requires a fairly high temperature, ranging from 20 • C to 40 • C, to grow [10]. Therefore, rice is highly sensitive to lowtemperature stress [11,12]. Cold stress can damage rice plants during any developmental stage from germination to maturity [13][14][15], with the reproductive phases, especially heading and flowering, being particularly susceptible [9,16]. ...
... A sound understanding of the spatiotemporal changes in cold stress and quantification of their impacts on rice growth and yield in China could help to accurately estimate rice yield losses before harvest, optimize strategies to cope with coldstress threats and guarantee China's food security [1,24,25]. Numerous previous studies have used experiments to analyze the mechanisms by which cold stress affects the biological functions and overall metabolism of rice in its different growth stages [11,12,17,26,27]; however, due to the lack of high-quality data on crop growth, yield and climate extremes spanning suitable spatial and temporal scales, our knowledge regarding the spatiotemporal characteristics of cold stress and their effects on crop growth and yield at relatively large spatial scales remains limited. ...
Short episodes of low-temperature stress during reproductive stages can cause significant crop yield losses, but our understanding of the dynamics of extreme cold events and their impact on rice growth and yield in the past and present climate remains limited. In this study, by analyzing historical climate, phenology and yield component data, the spatial and temporal variability of cold stress during the rice heading and flowering stages and its impact on rice growth and yield in China was characterized. The results showed that cold stress was unevenly distributed throughout the study region, with the most severe events observed in the Yunnan Plateau with altitudes higher than 1800 m. With the increasing temperature, a significant decreasing trend in cold stress was observed across most of the three ecoregions after the 1970s. However, the phenological-shift effects with the prolonged growing period during the heading and flowering stages have slowed down the cold stress decreasing trend and led to an underestimation of the magnitude of cold stress events. Meanwhile, cold stress during heading and flowering will still be a potential threat to rice production. The cold stress-induced yield loss is related to both the intensification of extreme cold stress and the contribution of related components to yield in the three regions.
