植物蔗糖转运蛋白

文章概述了植物蔗糖转运蛋白的结构、性质和类群的研究进展。     

蔗糖转运蛋白的调节

对影响植物蔗糖转运蛋白的表达和活性的各种内外调节因子作了综述.分别介绍了蔗糖转运蛋白在转录和翻译水平的调控、蛋白间的互作、激素协调、及外界环境因素等.     

植物体内蔗糖转运蛋白的功能和调控

蔗糖转运蛋白（sucrose transporter,SUT）负责蔗糖的跨膜运输,在韧皮部介导的源-库蔗糖运输和为库组织供应蔗糖的生理活动中起关键作用。本文介绍植物体内蔗糖转运蛋白基因家族、细胞定位与功能调节以及高等植物的蔗糖感受机制的研究进展。     

植物蔗糖转运蛋白及其功能调节研究进展

综述了高等植物蔗糖转运蛋白基因家族的分类,蔗糖转运蛋白的细胞定位,蔗糖转运蛋白的功能调节,以及果实中糖运转的特性等方面的研究进展,并提出了深入研究果实蔗糖运转蛋白的展望。     

水稻蔗糖转运蛋白研究进展

蔗糖转运蛋白是光合产物运输与分配调控网络中的重要节点,主要参与蔗糖从"源"到"库"的质外体运输,在蔗糖的感应、"源"器官装载、韧皮部长距离运输和"库"器官卸载中起重要作用。总结和分析了水稻蔗糖转运蛋白基因家族的组成、蛋白结构特点、表达与调控特性、生物学功能等方面的研究进展,在此基础上,提出了蔗糖转运蛋白基础理论和应用研究方面存在的不足及应予重视和加强的主要方向。     

高等植物蔗糖转运的分子调控

在高等植物中,蔗糖的合成、运输与分配是一个复杂的过程。蔗糖由源到库的运输不仅与植物的生长发育相关,还受到植物体内的激素水平以及外界环境条件变化等因素的影响。蔗糖转运蛋白介导了蔗糖在植物韧皮部的装载、运输和卸载,在某些库中的蔗糖转运和库组织分配的分子调控中起有重要的生理作用。此外,简要介绍了笔者实验室在橡胶树蔗糖转运蛋白基因研究方面的最新进展。     

植物蔗糖转运蛋白表达的调控因素与分子机制

植物光合作用的产物主要以蔗糖的形式在植物体内进行从源到库的运输.蔗糖转运蛋白是此过程的重要参与者,其表达和调控与植物中光合作用产物的分配紧密关联,从而调控着植物的生长发育、结果结实、抗逆抗病等性状.蔗糖转运蛋白的表达受到植物发育时期、外界环境条件及激素的影响.蔗糖转运蛋白的调控机制有转录因子的调节、基因内部序列调控、蛋...     

植物蔗糖转运蛋白的基因与功能

蔗糖是植物体内碳水化合物长距离转运的主要（甚至唯一）形式，为植物生长发育提供碳架与能量。蔗糖转运蛋白（sucrose transporter，SUT）负责蔗糖的跨膜运输，在韧皮部介导的源-库蔗糖运输，以及库组织的蔗糖供给中起关键作用。自从菠菜中克隆到第一个SUT基因以来，已先后有多个SUT基因的cDNA得到克隆与功能分析，涉及34种双子叶与单子叶植物。每种植物都有一个中等规模的SUT基因家族，其不同成员之间具有较高的氨基酸序列同源性，但在蔗糖吸收的动力学特性、转运底物的特异性和表达谱等方面存在差异。本文系统介绍国内外（主要是国外）在植物SUT基因的克隆、分类与进化、细胞定位与功能，以及研究方法等方面的研究进展，并简要介绍我们在橡胶树SUT基因研究上的初步结果。     

植物蔗糖转运蛋白的基因与功能

蔗糖是植物体内碳水化合物长距离转运的主要( 甚至唯一) 形式, 为植物生长发育提供碳架与能量。蔗糖转运蛋白(sucrose transporter, SUT)负责蔗糖的跨膜运输, 在韧皮部介导的源-库蔗糖运输, 以及库组织的蔗糖供给中起关键作用。自从菠菜中克隆到第一个SUT基因以来, 已先后有多个SUT基因的cDNA得到克隆与功能分析, 涉及34种双子叶与单子叶植物。每种植物都有一个中等规模 的SUT基因家族, 其不同成员之间具有较高的氨基酸序列同源性, 但在蔗糖吸收的动力学特性、转运底物的特异性和表达谱等方面存在差异。本文系统介绍国内外(主要是国外)在植物SUT基因的克隆、分类与进化、细胞定位与功能, 以及研究方法等方面的研究进展, 并简要介绍我们在橡胶树SUT基因研究上的初步结果。     

VIGS技术鉴定木薯糖转运蛋白Mesweet18的功能研究

糖转运蛋白（sugar will eventually be exported transporter,SWEET）在植物运输糖类、生殖和发育、逆境性、与病原体互作等方面发挥着重要作用。选择木薯糖转运蛋白Mesweet18基因沉默的靶基因区域,通过病毒诱导的基因沉默(virus-induced gene silencing,VIGS)技术注射木薯SC9的盆栽苗叶片。qRT-PCR结果表明,Mesweet18在沉默植株中的表达量显著下调,分别是对照的46.80%、30.23%、21.12%。叶片叶绿素和可溶性糖含量检测结果表明,与对照相比,叶绿素a、b和总含量均出现不同程度的下降,蔗糖和果糖含量显著增加,而葡萄糖含量出现轻微下降。研究Mesweet18在木薯中的分子功能,为深入研究糖转运蛋白SWEET在木薯中的分子机制奠定了基础。     

NaCl-resistant variant cells isolated from sweet potato cell suspensions

Salt-resistant cells of sweet potato (Ipomoea batatas L.) were selected by subculturing cell suspensions (11 transfers at 15-day intervals) in MS medium supplemented with 1% NaCl (170.9 mM NaCl).Selected cells showed a brownish pigmentation, and exhibited morphological changes (they were smaller and rounder than non-selected cells). The change in coloration was reversible when the selected cells were subcultured in medium without NaCl. The reduction in size was partially reversed but the change in form was not reversible when selected cells were subcultured 5 times at 15-day intervals in the absence of NaCl.Selected cells exhibited NaCl-tolerance when they were cultured in medium with 1% NaCl and subsequently transferred to NaCl free medium for 3 passages. This finding suggests that the acquired trait is stable for at least 3 passages.     

Induction of umbelliferone in sweet potato cell suspension culture using mercuric chloride

HgCl₂ was used at up to 10 mg l^–1 as an elicitor of phytoalexins in sweet potato (Ipomoea batatas (L.) Lam. cv Centennial) cell suspension cultures. Maximum stimulation of a coumarin compound was after one day of exposure using 1 mg HgCl₂ l^–1. The compound was identified by HPLC and GC-MS analyses as 7-hydroxycoumarin (umbelliferone).     

Feeding by adult sweet potato weevils, Cylas formicarius elegantulus, on sweet potato leaves

A bioassay was developed to quantify the feeding of adult sweet potato weevils, Cylas formicarius elegantulus (Summers) (Coleoptera; Curculionidae) on the foliage of four cultivars (Centennial, Jewel, Resisto and Regal) of sweet potato (Ipomoea batatas (L.) Lam.) (Convolvulaceae). Weevils fed along the leaf veins, preferring the lower to the upper leaf surface. Males and females had similar levels of feeding. Different levels of feeding by female weevils were observed between cultivars in dual-choice bioassays with Centennial, a susceptible cultivar in field-plot experiments, being most preferred and Resisto least preferred. However, these feeding differences were not observed in no-choice bioassays. Little difference was observed in the leaf surface chemistry of the four cultivars.

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Résumé L'étude a porté sur la consommation pendant 12 h, en boîtes de Pétri de diamètre 9 cm, de rondelles de 2 cm de diamètre de feuilles de 4 cultivars,—Centennial, Jewel, Resisto, Regal—, d'I. batatas par C. formicarius elegantulus. Les charançons ont consommé le long des nervures, préférant la face inférieure à la face supérieure des feuilles. Un index de consommation a été calculé en fonction de la longueur de nervure ayant servi à la consommation, rapportée à la longueur totale des nervures de la surface exposée.Les niveaux de consommation des mâles et des femelles étaient semblables. En présence de choix binaires, le cultivar Centennial a été le plus consommé, et le cultivar Resisto, le moins, par les femelles. De telles préférences n'ont pas été observées en l'absence de choix.La composition chimique de la surface de la feuille a été analysée par chromatographie en phase gazeuse. 8 pics principaux identiques ont été observés chez les 4 cultivars, mais ils avaient différentes hauteurs.

     

红薯叶片浸提液对5种主要农田杂草种子萌发及幼苗生长的化感作用

以发芽率、发芽势、根长、茎长和鲜重变化为种子萌发和幼苗生长参数,研究了作物红薯叶片水浸液对云南省农田5种恶性杂草牛膝菊、藿香蓟、鬼针草、马唐和稗草的化感作用。结果表明,红薯叶片水浸液对5种受体杂草种子发芽率的影响不明显,但对发芽势有显著抑制作用。牛膝菊、藿香蓟、鬼针草和马唐的根长和生物量随红薯叶片水浸液浓度增加而显著降低,其中对马唐的抑制最强,高浓度0.1 g/m L时对根长和生物量抑制率分别为92.04%和73.33%,而低浓度0.0125 g/m L时分别为40.99%和46.67%;其次为鬼针草、藿香蓟、牛膝菊;最差的是稗草,随浓度的变化趋势均不明显。随红薯叶片水浸液浓度增加牛膝菊、鬼针草和马唐的茎长显著地降低,其中对马唐的抑制最强,高浓度0.1 g/m L和低浓度0.0125 g/m L时分别为86.85%和70.64%;其次为鬼针草和牛膝菊;相反藿香蓟和稗草的茎长随浓度增加而显著增加,高浓度0.1 g/m L和低浓度0.0125 g/m L时对藿香蓟的促进率分别为86.97%和16.03%。红薯叶片水浸液低浓度0.0125 g/m L时对牛膝菊的茎长和生物量有促进作用(低促高抑)。从化感作用响应指数和综合效应指数的综合对比来看,红薯对牛膝菊、藿香蓟、鬼针草、马唐具有显著的化感抑制作用,随浓度增加其抑制能力显著增加;其中对马唐的为最强,其次为鬼针草、牛膝菊和藿香蓟,相反对稗草具有促进作用(除了浓度0.1 g/m L)。所有这些表明,红薯叶片水浸液对5种杂草化感作用的敏感性趋势总体为:马唐鬼针草牛膝菊藿香蓟,最不敏感或者具有促进作用的是稗草。     

Heritability of regeneration in tissue cultures of sweet potato (Ipomoea batatas L.)

Summary A population of open-pollinated progeny from 12 parents, and the 12 parents, was surveyed for in vitro growth and regeneration characteristics. Four different tissue culture procedures involving different media and the use of different explants to initiate the cultures were used. Petiole explants from young leaves were used as explants for initiation of callus cultures. These were evaluated for callus growth rate, friability, and callus color and texture, before transferring to each of three different regeneration media for evaluation of morphogenetic potential. Small shoot tips also were used to initiate callus cultures, which were evaluated for the same growth characteristics and transferred to growth-regulator free regeneration media. Regeneration occurred through root or shoot regeneration or through embryogenesis. Tissue culture treatment effects, as well as genotypic effects, were highly significant in determining: the types of callus produced, callus growth rates, color and texture on the two types of media used for the second and third subcultures. The family x treatment interaction was generally not statistically significant, affecting only callus color. Estimates of narrow sense heritability for callus growth rate in both the second and third subcultures were high enough (0.35 and 0.63, respectively) for the evaluation of parental lines for selection procedures. These characteristics were also the only early culture callus traits that were consistently correlated with later morphogenesis of the cultures. They were negatively correlated with root or shoot regeneration. The occurence of somatic embryogenesis was not correlated with early callus growth characteristics. Genetic and treatment effects were highly significant in the evaluation of morphogenetic potential, through root or shoot regeneration, or through embryogenesis. Regeneration of all types was of low frequency for all procedures, expressed in 11% of the cultures of the total population.Paper No. 9906 of the Journal Series of the North Carolina Agricultural Research Service, Raleigh, NC 27695-7601, USA. From a thesis submitted by the senior in partial fulfillment of the requirements for the Ph.D. degree     

Expression of green-fluorescent protein gene in sweet potato tissues

Green-fluorescent protein (GFP) gene expression, transient and stable after electroporation and particle bombardment, was analyzed in tissues of sweet potato cv.Beauregard. Leaf and petiole tissues were used for protoplast isolation and electroporation. After 48 h, approximately 25–30% of electroporated mesophyll cell protoplasts regenerated cell walls, and of these, 3% expressed GFP. Stable expression of GFP after four weeks of culture was observed in 1.0% of the initial GFP positive cells. In a separate experiment, we observed 600–700 loci expressing GFP 48 h after bombarding leaf tissue or embryogenic calli, and stable GFP-expressing sectors were seen in leaf-derived embryogenic calli after four weeks of protoplast culture without selection. These results demonstrate GFP gene expression in sweet potato tissues. Screening for GFP gene expression may prove useful to improve transformation efficiency and to facilitate detection of transformed sweet potato plants.     

Structural relationship among the members of a multigene family coding for the sweet potato tuberous root storage protein

Sporamin, the major soluble protein of the sweet potato tuberous root, is coded for by a multigene family. Fourty-nine essentially full-length sporamin cDNAs isolated from tuberous root cDNA library have been classified by cross hybridization, restriction endonuclease cleavage pattern and ribonuclease cleavage mapping. All the cDNAs fall into one of the two distinct homology groups, subfamilies A and B, which correspond to the polypeptide classes sporamin A and B, respectively. At least 5 different sequences are detected in both of the 22 sporamin A and 27 sporamin B cDNAs. Comparison of the nucleotide sequences of the coding region of three each of sporamin A and B subfamily members, four from cDNAs and two from genomic clones, indicates that intra-subfamily homologies (94 to 98%) are much higher than inter-subfamily homologies (82 to 84%), and there are deletions or insertions of one or two codons at three locations which characterize each subfamily. Large portions of base substitutions in the coding region accompany amino acid substitutions. In contrast to the coding region, most of the structural differences among the members in the 5 and 3 noncoding regions are deletions or insertions.     

Transformation of sweet potato tissues with green-fluorescent protein gene

Summary The expression of the green-fluorescent protein (GFP) gene from Aequorea victoria (jellyfish) was analyzed by transient and stable expression in sweet potato Ipomoea batatas L. (Lam.) ev. Beauregard tissues by electroporation and particle bombardment. Leaf and petiole segments from in vitro-raised young plantlets were used for protoplast isolation and electroporation. Embyrogenic callus was also produced from leaf segments for particle bombardment experiments. A buffer solution containing 1×10⁶ protoplasts ml⁻¹ was mixed with plasmid DNA containing the GFP gene, and electroporated at 375 V cm⁻¹. Approximately 25–30% of electroporated mesophyll cell protoplasts subsequently cultured in KM8P medium regenerated cell walls after 48 h. Of these, 3% emitted bright green fluorescence when exposed to UV-blue light at 395 nm. Transformed cells continued to grow after embedding in KM8P medium solidifed with 1.2% SeaPlaque agarose. Stable expression of GFP was observed after 4 wk of culture in approximately 1.0% of the initial GFP positive cells (27.5 GFP positive micro callases out of 3024 cells which transiently expressed GFP 48 h after electroporation). In a separate experiment, 600–700 bright green spots were observed per plate 48 h after bombarding leaf segments or embryogenic cellus. In bombarded cultures, several stable GEP-expressing sectors were observed in leafderived embryogenic callus grown without selection for 4 wk. These results show that GFP gene expression can occur in various sweet potato tissues, and that it may be a useful sereenable marker to improve transformation efficiency and obtain transgenic sweet potato plants.     

Transgenic sweet potato plants obtained byAgrobacterium tumefaciens-mediated transformation

Stable expression of foreign genes was achieved in sweet potato (Ipomoea batatas (L.) Lam) plants using anAgrobacterium tumefaciens mediated system. Embryogenic calluses produced from apical meristems of cultivar White Star were multiplied and cocultivated withA. tumefaciens strain EHA101 harboring a binary vector containing the -glucuronidase (GUS) and neomycin phosphotransferase (NPT II) genes. The calluses were transferred to selective regeneration medium and kanamycin resistant embryos were recovered which developed into morphologically normal plants. Histochemical and fluorimetric GUS assays of plants developed from the kanamycin resistant embryos were positive. Amplified DNA fragments were produced in polymerase chain reactions using GUS-specific primers and DNA from these plants. Transformation was confirmed by Southern analysis of the GUS gene. With the developed method, transgenic sweet potato plants were obtained within 7 weeks. This method will allow genetic improvement of this crop by the introduction of agronomically important genes.Florida Agricultural Experiment Station Journal Series N-02231. This research was partially supported by CNP_q/RHAE (Brazil).