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1.
    
Sulfur is required for the biosynthesis of cysteine, methionine and numerous other metabolites, and thus is critical for cellular metabolism and various growth and developmental processes. Plants are able to sense their physiological state with respect to sulfur availability, but the sensor remains to be identified. Here we report the isolation and characterization of two novel allelic mutants of Arabidopsis thaliana, sel1‐15 and sel1‐16, which show increased expression of a sulfur deficiency‐activated gene βglucosidase 28 (BGLU28). The mutants, which represent two different missense alleles of SULTR1;2, which encodes a high‐affinity sulfate transporter, are defective in sulfate transport and as a result have a lower cellular sulfate level. However, when treated with a very high dose of sulfate, sel1‐15 and sel1‐16 accumulated similar amounts of internal sulfate and its metabolite glutathione (GSH) to wild‐type, but showed higher expression of BGLU28 and other sulfur deficiency‐activated genes than wild‐type. Reduced sensitivity to inhibition of gene expression was also observed in the sel1 mutants when fed with the sulfate metabolites Cys and GSH. In addition, a SULTR1;2 knockout allele also exhibits reduced inhibition in response to sulfate, Cys and GSH, consistent with the phenotype of sel1‐15 and sel1‐16. Taken together, the genetic evidence suggests that, in addition to its known function as a high‐affinity sulfate transporter, SULTR1;2 may have a regulatory role in response to sulfur nutrient status. The possibility that SULTR1;2 may function as a sensor of sulfur status or a component of a sulfur sensory mechanism is discussed.  相似文献   

2.
    
Cytokinin is an adenine derivative plant hormone that generally regulates plant cell division and differentiation in conjunction with auxin. We report that a major cue for the negative regulation of sulfur acquisition is executed by cytokinin response 1 (CRE1)/wooden leg (WOL)/Arabidopsis histidine kinase 4 (AHK4) cytokinin receptor in Arabidopsis root. We constructed a green fluorescent protein (GFP) reporter system that generally displays the expression of the high-affinity sulfate transporter SULTR1;2 in Arabidopsis roots. GFP under the control of SULTR1;2 promoter showed typical sulfur responses that correlate with the changes in SULTR1;2 mRNA levels; accumulation of GFP was induced by sulfur limitation (-S), but was repressed in the presence of reduced sulfur compounds. Among the plant hormones tested, cytokinin significantly downregulated the expression of SULTR1;2. SULTR1;1 conducting sulfate uptake in sultr1;2 mutant was similarly downregulated by cytokinin. Downregulation of SULTR1;1 and SULTR1;2 by cytokinin correlated with the decrease in sulfate uptake activities in roots. The effect of cytokinin on sulfate uptake was moderated in the cre1-1 mutant, providing genetic evidence for involvement of CRE1/WOL/AHK4 in the negative regulation of high-affinity sulfate transporters. These data demonstrated the physiological importance of the cytokinin-dependent regulatory pathway in acquisition of sulfate in roots. Our results suggested that two different modes of regulation, represented as the -S induction and the cytokinin-dependent repression of sulfate transporters, independently control the uptake of sulfate in Arabidopsis roots.  相似文献   

3.
  总被引:12,自引:0,他引:12  
Sulfate transporters present at the root surface facilitate uptake of sulfate from the environment. Here we report that uptake of sulfate at the outermost cell layers of Arabidopsis root is associated with the functions of highly and low-inducible sulfate transporters, Sultr1;1 and Sultr1;2, respectively. We have previously reported that Sultr1;1 is a high-affinity sulfate transporter expressed in root hairs, epidermal and cortical cells of Arabidopsis roots, and its expression is strongly upregulated in plants deprived of external sulfate. A novel sulfate transporter gene, Sultr1;2, identified on the BAC clone F28K19 of Arabidopsis, encoded a polypeptide of 653 amino acids that is 72.6% identical to Sultr1;1 and was able to restore sulfate uptake capacity of a yeast mutant lacking sulfate transporter genes (K(m) for sulfate = 6.9 +/- 1.0 microm). Transgenic Arabidopsis plants expressing the fusion gene construct of the Sultr1;2 promoter and green fluorescent protein (GFP) showed specific localization of GFP in the root hairs, epidermal and cortical cells of roots, and in the guard cells of leaves, suggesting that Sultr1;2 may co-localize with Sultr1;1 in the same cell layers at the root surface. Sultr1;1 mRNA was abundantly expressed under low-sulfur conditions (50-100 microm sulfate), whereas Sultr1;2 mRNA accumulated constitutively at high levels under a wide range of sulfur conditions (50-1500 microm sulfate), indicating that Sultr1;2 is less responsive to changes in sulfur conditions. Addition of selenate to the medium increased the level of Sultr1;1 mRNA in parallel with a decrease in the internal sulfate pool in roots. The level of Sultr1;2 mRNA was not influenced under these conditions. Antisense plants of Sultr1;1 showed reduced accumulation of sulfate in roots, particularly in plants treated with selenate, suggesting that the inducible transporter Sultr1;1 contributes to the uptake of sulfate under stressed conditions.  相似文献   

4.
  总被引:1,自引:0,他引:1  
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5.
    
Plants play a prominent role as sulfur reducers in the global sulfur cycle. Sulfate, the major form of inorganic sulfur utilized by plants, is absorbed and transported by specific sulfate transporters into plastids, especially chloroplasts, where it is reduced and assimilated into cysteine before entering other metabolic processes. How sulfate is transported into the chloroplast, however, remains unresolved; no plastid‐localized sulfate transporters have been previously identified in higher plants. Here we report that SULTR3;1 is localized in the chloroplast, which was demonstrated by SULTR3;1‐GFP localization, Western blot analysis, protein import as well as comparative analysis of sulfate uptake by chloroplasts between knockout mutants, complemented transgenic plants, and the wild type. Loss of SULTR3;1 significantly decreases the sulfate uptake of the chloroplast. Complementation of the sultr3;1 mutant phenotypes by expression of a 35S‐SULTR3;1 construct further confirms that SULTR3;1 is one of the transporters responsible for sulfate transport into chloroplasts.  相似文献   

6.
  总被引:3,自引:0,他引:3  
  相似文献   

7.
  总被引:3,自引:0,他引:3  
Plant responses to auxin and phosphate (Pi) starvation are closely linked. However, the underlying mechanisms connecting auxin to phosphate starvation (?Pi) responses are largely unclear. Here, we show that OsARF16, an auxin response factor, functions in both auxin and ?Pi responses in rice (Oryza sativa L.). The knockout of OsARF16 led to primary roots (PR), lateral roots (LR) and root hair losing sensitivity to auxin and ?Pi response. OsARF16 expression and OsARF16::GUS staining in PR and LR of rice Nipponbare (NIP) were induced by indole acetic acid and ?Pi treatments. In ?Pi conditions, the shoot biomass of osarf16 was slightly reduced, and neither root growth nor iron content was induced, indicating that the knockout of OsARF16 led to loss of response to Pi deficiency in rice. Six phosphate starvation‐induced genes (PSIs) were less induced by ?Pi in osarf16 and these trends were similar to a knockdown mutant of OsPHR2 or AtPHR1, which was a key regulator under ?Pi. These data first reveal the biological function of OsARF16, provide novel evidence of a linkage between auxin and ?Pi responses and facilitate the development of new strategies for the efficient utilization of Pi in rice.  相似文献   

8.
光敏色素A是植物远红光信号的关键受体,在植物光信号转导途径中起重要作用。一些具有重要功能的基因(如生长素反应因子8:auxin response factor 8,ARF8)受到PhyA调控。本实验拟通过构建PhyA基因反义株系,研究PhyA调控ARF8等重要功能基因表达的机理。以培养7 d的拟南芥幼苗为材料提取RNA,利用RT-PCR技术扩增出PhyA的全长CDS,将其反向插入表达载体pMD1得到反义表达载体pMD1-PhyA CDSR,并通过农杆菌介导转化拟南芥,经卡那霉素抗性平板筛选和PCR鉴定得到13个PhyA转基因株系。pMD1-PhyA CDSR及其转基因株系的获得为研究PhyA调控ARF8等基因表达的机理奠定了材料基础。  相似文献   

9.
Plant fertility defects induced by the enhanced expression of microRNA167   总被引:8,自引:0,他引:8  
Ru P  Xu L  Ma H  Huang H 《Cell research》2006,16(5):457-465
  相似文献   

10.
生长素响应因子与植物的生长发育   总被引:4,自引:0,他引:4  
刘振华  于延冲  向凤宁 《遗传》2011,33(12):1335-1346
生长素响应因子(Auxin response factor, ARF)作为一类调控生长素响应基因表达的转录因子, 是生长素研究的重要内容。它可与生长素响应基因启动子区域内的生长素响应元件结合, 促进或抑制基因的表达。文章介绍了植物体内ARF家族的分子生物学近年来的研究进展, 同时也讨论了ARF转录因子的结构、ARF基因的表达调控、ARF在植物生长发育及信号转导中的作用以及ARF对靶基因的调控机制等内容。植物ARF成员都有一定的同源性, 大多含有4个结构域, 在多种组织和器官中都有表达, 其表达受到转录及转录后调控, 并且在介导生长素与其它激素之间相互作用方面扮演重要角色。  相似文献   

11.
ABC转运蛋白超家族结构和功能复杂多样, 包含ABCA-ABCH八个亚家族。ABCB是ABC转运蛋白的一个亚家族, 多数定位于质膜, 少数定位于线粒体膜或叶绿体膜。ABCB与其它生长素转运蛋白(AUX1/LAX、PIN)共同参与调控植物生长素的极性运输, 在植物生长发育的各个阶段发挥作用。此外, ABCB转运蛋白还调控植物的向性运动和重金属抗性等过程。近年来, 随着越来越多植物全基因组测序的完成, ABCB亚家族在禾谷类单子叶植物水稻(Oryza sativa)、玉米(Zea mays)和高粱(Sorghum bicolor)中的生物学功能开始有少量报道, 然而多数ABCB转运蛋白的功能尚未得到阐释。该文对拟南芥(Arabidopsis thaliana)和禾谷类作物ABCB转运蛋白的研究进展进行综述, 以期为全面揭示ABCB亚家族生物学功能提供线索。  相似文献   

12.
  总被引:4,自引:0,他引:4  
  相似文献   

13.
    
Exogenously applied brassinolide (BL) increased both gravitropic curvature and length of primary roots of Arabidopsis at low concentration (10(-10) M), whereas at higher concentration, BL further increased gravitropic curvature while it inhibited primary root growth. BRI1-GFP plants possessing a high steady-state expression level of a brassinosteroid (BR) receptor kinase rendered the plant's responses to gravity and root growth more sensitive, while BR-insensitive mutants, bri1-301 and bak1, delayed root growth and reduced their response to the gravitropic stimulus. The stimulatory effect of BL on the root gravitropic curvature was also enhanced in auxin transport mutants, aux1-7 and pin2, relative to wild-type plants, and increasing concentration of auxin attenuated BL-induced root sensitivity to gravity. Interestingly, IAA treatment to the roots of bri1-301 and bak1 plants or of plants pretreated with a BL biosynthetic inhibitor, brassinazole, increased their sensitivity to gravity, while these treatments for the BL-hypersensitive transgenic plants, BRI1-GFP and 35S-BAK1, were less effective. Expression of a CYP79B2 gene, encoding an IAA biosynthetic enzyme, was suppressed in BL-hypersensitive plant types and enhanced in BL-insensitive or -deficient plants. In conclusion, our results indicate that BL interacts negatively with IAA in the regulation of plant gravitropic response and root growth, and its regulation is achieved partly by modulating biosynthetic pathways of the counterpart hormone.  相似文献   

14.
ABC转运蛋白超家族结构和功能复杂多样, 包含ABCA-ABCH八个亚家族。ABCB是ABC转运蛋白的一个亚家族, 多数定位于质膜, 少数定位于线粒体膜或叶绿体膜。ABCB与其它生长素转运蛋白(AUX1/LAX、PIN)共同参与调控植物生长素的极性运输, 在植物生长发育的各个阶段发挥作用。此外, ABCB转运蛋白还调控植物的向性运动和重金属抗性等过程。近年来, 随着越来越多植物全基因组测序的完成, ABCB亚家族在禾谷类单子叶植物水稻(Oryza sativa)、玉米(Zea mays)和高粱(Sorghum bicolor)中的生物学功能开始有少量报道, 然而多数ABCB转运蛋白的功能尚未得到阐释。该文对拟南芥(Arabidopsis thaliana)和禾谷类作物ABCB转运蛋白的研究进展进行综述, 以期为全面揭示ABCB亚家族生物学功能提供线索。  相似文献   

15.
植物非生物胁迫诱导启动子顺式元件及转录因子研究进展   总被引:3,自引:0,他引:3  
顺式作用元件(cix-acting element)是与结构基因串联的特定DNA序列,是转录因子的结合位点,它们通过与转录因子结合调控基因转录的精确起始和转录效率,在植物基因表达调控过程中起着重要的作用.非生物胁迫诱导基因的表达受其上游启动子顺式作用元件及转录因子的调控,目前已发现了多种与非生物胁迫相关的顺势作用元件及转录因子,如DRE元件及DREB类转录因子、MYB元件及MYB类转录因子、GT-1元件及GT-1类转录因子等.顺式作用元件及转录因子的研究对研究植物非生物胁迫相关基因的表达调控具有重要意义,综述植物非生物胁迫诱导启动子功能元件及转录因子的研究进展.  相似文献   

16.
    
The plant hormone auxin controls many aspects of plant development. Membrane trafficking processes, such as secretion, endocytosis and recycling, regulate the polar localization of auxin transporters in order to establish an auxin concentration gradient. Here, we investigate the function of the Arabidopsis thaliana R-SNAREs VESICLE-ASSOCIATED MEMBRANE PROTEIN 721 (VAMP721) and VAMP722 in the post-Golgi trafficking required for proper auxin distribution and seedling growth. We show that multiple growth phenotypes, such as cotyledon development, vein patterning and lateral root growth, were defective in the double homozygous vamp721 vamp722 mutant. Abnormal auxin distribution and root patterning were also observed in the mutant seedlings. Fluorescence imaging revealed that three auxin transporters, PIN-FORMED 1 (PIN1), PIN2 and AUXIN RESISTANT 1 (AUX1), aberrantly accumulate within the cytoplasm of the double mutant, impairing the polar localization at the plasma membrane (PM). Analysis of intracellular trafficking demonstrated the involvement of VAMP721 and VAMP722 in the endocytosis of FM4-64 and the secretion and recycling of the PIN2 transporter protein to the PM, but not its trafficking to the vacuole. Furthermore, vamp721 vamp722 mutant roots display enlarged trans-Golgi network (TGN) structures, as indicated by the subcellular localization of a variety of marker proteins and the ultrastructure observed using transmission electron microscopy. Thus, our results suggest that the R-SNAREs VAMP721 and VAMP722 mediate the post-Golgi trafficking of auxin transporters to the PM from the TGN subdomains, substantially contributing to plant growth.  相似文献   

17.
18.
为确定拟南芥抗逆相关基因AtRPK1启动子的顺式功能元件;对其启动子区进行了分段克隆。通过5′端缺失方法得到203、316、604、809 bp 4个启动子片段;分别构建成p1300-pro-GUS表达载体;并转入拟南芥;进行GUS染色和GUS定量检测。通过对809 bp全长启动子转基因拟南芥GUS染色发现;转基因拟南芥的叶片、茎、花、根中均有表达;在分生能力强的组织和维管束集中的组织;AtRPK1基因启动子具有较高启动表达能力。5′端缺失启动子检测结果表明;转录起始点到启动子上游114位点区域包含AtRPK1基因启动子的关键顺式作用元件。对启动子缺失片段转基因植株利用200 mmol·L-1 NaCl胁迫3 h后;β-葡萄糖苷酸酶活力定量检测结果表明;在启动子上游-19位点处的GT-1顺式作用元件GAAAAA可能直接与盐胁迫应答相关。  相似文献   

19.
We have developed an Arabidopsis thaliana/Myzus persicae model system to allow the dissection of plant/insect interactions at a molecular genetic level. This allows the examination of the role of single plant genes in the interaction between the plant and an aphid. Our initial studies have exploited an Arabidopsis genotype in which the function of the amino acid transporter ANT1 has been abolished. This mutation results in a change in the proportions of several amino acids within the phloem sieve elements (SEs) resulting in an increase in the proportion of essential amino acids. This has been measured using aphid stylectomy to collect SE samples, followed by a novel micellar electrokinetic chromatography method for amino acid analysis. The SE content represents the aphid's diet, and use of electrical penetration graph technology and honeydew clocks have demonstrated that this altered diet results in a change in the feeding rate of the aphid. Balance sheets can be produced to show the amount (nmoles/24 h) of each of 18 amino acids taken up and excreted by aphids feeding on wild type and ant1 mutant plants. The data show that aphids feeding on the ant1 mutant take up larger amounts of amino acids. However, we could not detect any effect on the reproductive rate of the aphids. The results show that, under experimental conditions, this model system can be used to identify plant genes that control the behaviour and fecundity of an insect pest.  相似文献   

20.
  总被引:9,自引:0,他引:9  
The hormone auxin is transported in plants through the combined actions of diffusion and specific auxin influx and efflux carriers. In contrast to auxin efflux, for which there are well documented inhibitors, understanding the developmental roles of carrier-mediated auxin influx has been hampered by the absence of specific competitive inhibitors. However, several molecules that inhibit auxin influx in cultured cells have been described recently. The physiological effects of two of these novel influx carrier inhibitors, 1-naphthoxyacetic acid (1-NOA) and 3-chloro-4-hydroxyphenylacetic acid (CHPAA), have been investigated in intact seedlings and tissue segments using classical and new auxin transport bioassays. Both molecules do disrupt root gravitropism, which is a developmental process requiring rapid auxin redistribution. Furthermore, the auxin-insensitive and agravitropic root-growth characteristics of aux1 plants were phenocopied by 1-NOA and CHPAA. Similarly, the agravitropic phenotype of inhibitor-treated seedlings was rescued by the auxin 1-naphthaleneacetic acid, but not by 2,4-dichlorophenoxyacetic acid, again resembling the relative abilities of these two auxins to rescue the phenotype of aux1. Further investigations have shown that none of these compounds block polar auxin transport, and that CHPAA exhibits some auxin-like activity at high concentrations. Whilst results indicate that 1-NOA and CHPAA represent useful tools for physiological studies addressing the role of auxin influx in planta, 1-NOA is likely to prove the more useful of the two compounds.  相似文献   

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