Polar PIN localization directs auxin flow in plants

Polar flow of the phytohormone auxin requires plasma membrane-associated PIN proteins and underlies multiple developmental processes in plants. Here we address the importance of the polarity of subcellular PIN localization for the directionality of auxin transport in Arabidopsis thaliana. Expression of different PINs in the root epidermis revealed the importance of PIN polar positions for directional auxin flow and root gravitropic growth. Interfering with sequence-embedded polarity signals directly demonstrates that PIN polarity is a primary factor in determining the direction of auxin flow in meristematic tissues. This finding provides a crucial piece in the puzzle of how auxin flow can be redirected via rapid changes in PIN polarity.     

生长素在烟草表皮毛中的极性运输及对细胞伸长的影响

利用生长素极性运输转运蛋白PIN1与增强绿色荧光蛋白EGFP的融合,对PIN1进行了荧光标记,并以烟草表皮毛为模式,开展了PIN1对生长素极性运输及对细胞伸长生长影响的研究。采用DNA重组技术,将融合标记基因EGFP–PIN1置于拟南芥表皮毛特异表达基因GL2的启动子调控下,构建成含GL2pro::EGFP–PIN1的Ti质粒,以根癌农杆菌叶盘共培转化法将重组标记基因转化至烟草WS38中,筛选鉴定出多株转基因烟草。通过对这些转基因烟草表皮毛进行显微荧光观察,结果发现,标记的绿色荧光信号集中分布在表皮毛细胞的间隔区,表现为明显的极性分布现象。用生长素极性运输抑制剂三碘苯甲酸(TIBA)处理后,表皮毛的伸长生长受到抑制,细胞中荧光的分布极性减弱。说明生长素在烟草表皮毛中的极性分布对烟草表皮毛伸长起关键作用,抑制生长素的极性运输不只抑制表皮毛的细胞伸长,同时还影响到生长素极性运输蛋白PIN的极性分布。     

PIN proteins perform a rate-limiting function in cellular auxin efflux

Intercellular flow of the phytohormone auxin underpins multiple developmental processes in plants. Plant-specific pin-formed (PIN) proteins and several phosphoglycoprotein (PGP) transporters are crucial factors in auxin transport-related development, yet the molecular function of PINs remains unknown. Here, we show that PINs mediate auxin efflux from mammalian and yeast cells without needing additional plant-specific factors. Conditional gain-of-function alleles and quantitative measurements of auxin accumulation in Arabidopsis and tobacco cultured cells revealed that the action of PINs in auxin efflux is distinct from PGP, rate-limiting, specific to auxins, and sensitive to auxin transport inhibitors. This suggests a direct involvement of PINs in catalyzing cellular auxin efflux.     

AXR4 is required for localization of the auxin influx facilitator AUX1

The AUX1 and PIN auxin influx and efflux facilitators are key regulators of root growth and development. For root gravitropism to occur, AUX1 and PIN2 must transport auxin via the lateral root cap to elongating epidermal cells. Genetic studies suggest that AXR4 functions in the same pathway as AUX1. Here we show that AXR4 is a previously unidentified accessory protein of the endoplasmic reticulum (ER) that regulates localization of AUX1 but not of PIN proteins. Loss of AXR4 resulted in abnormal accumulation of AUX1 in the ER of epidermal cells, indicating that the axr4 agravitropic phenotype is caused by defective AUX1 trafficking in the root epidermis.     

SLPIN6基因沉默对番茄抗旱性的影响

SLPIN6基因是番茄PIN家族一员,番茄PIN家族是一类生长素运输体蛋白家族,调控生长素极性运输.研究表明,干旱胁迫改变植物生长素极性运输平衡,影响植物抗旱性.团队前期研究发现SLPIN6基因在干旱胁迫时表达量显著上调,可能参与番茄植株抗旱应答调控.为进一步明确该基因抗旱调节功能,试验采用VIGS方法对SLPIN6基因作沉默处理,通过观察番茄植株抗旱表型及测定抗逆生理指标变化,发现SLPIN6基因沉默后番茄植株与对照相比,沉默番茄植株萎蔫程度加重,抗逆生理指标差异明显,表明SLPIN6基因参与番茄抗旱应答调控,具有抗旱调节功能.     

IAA及其运输载体PIN对香梨萼片脱落与宿存影响的研究

目前我国库尔勒香梨种植栽培面积逐步增大,产量大幅度升高,脱萼果减少,果肉质地变硬,石细胞含量增多,可食比例减少,风味口感下降,品质明显下降, 严重影响香梨的销售情况。而影响‘库尔勒香梨’果萼发脱落或宿存的因素存在许多方面,本文主要从香梨萼片发育、生长素对香梨萼片脱落或宿存的影响以及从分子层面阐述生长素极性运输载体PIN蛋白和该蛋白如何调控生长素运输与脱落,为提高香梨果萼脱落率以及改善果实品质及外观有重要意义。     

生长素运输机制研究进展

AUX1/LAX蛋白是生长素运入载体,而PIN蛋白是生长素运出载体。MDR/PGP蛋白也参与生长素运输。生长素运输是通过生长素载体将生长素载入质膜产生的内体,以及内体产生的小泡再循环实现的。生长素作为激素与形态发生素,生长素运输调控细胞的分裂与分化,同时在植物向性生长与维持植物的顶端优势中也发挥重要作用。     

The HD-Zip transcription factor GhHB12 represses plant height by regulating the auxin signaling in cotton

Upland cotton (Gossypium hirsutum L.) is the most important natural textile fiber crop worldwide. Plant height (PH) is a significant component of plant architecture, strongly influencing crop cultivation patterns, overall yield, and economic coefficient. However, cotton genes regulating plant height have not been fully identified. Previously, an HD-Zip gene (GhHB12) was isolated and characterized in cotton, which regulates the abiotic and biotic stress responses and the growth and development processes. In this study, we showed that GhHB12 was induced by auxin. Moreover, overexpression of GhHB12 induces the expression of HY5, ATH1, and HAT4, represses the spatial-temporal distribution, polar transport, and signaling of auxin, alters the expression of genes involved in cell wall expansion, and restrains the plant height in cotton. These results suggest a role of GhHB12 in regulating cotton plant height, which could be achieved by affecting the auxin signaling and cell wall expansion.     

水稻PIN家族的生物信息学分析

作为植物中最重要的生长素外输载体,PIN家族在各种植物中都拥有众多成员。对水稻基因组的BLAST搜索获得了12个PIN家族成员,分析发现:水稻PIN基因不均衡地分布在基因组染色体上;其内含子、外显子结构类似;PIN蛋白质拥有典型的载体蛋白序列特征,即亲/疏水性反复变化,存在多次跨膜结构域;几乎所有PIN蛋白都有一个NPNXY的内化结构域和7个功能未知的基序;PIN在早期即分化为两组成员,主要区别在于中间亲水环的部分缺失;并且在后来发生了支系特异的复制事件,从而形成了众多旁系同源基因。     

十字花科植物PIN3基因调控元件及表达分析

为探明十字花科不同物种PIN3基因的表达调控差异,从拟南芥(Arabidopsis thaliala)、红花荠菜(Capsella rubella)、白菜(Brassica rapa)、油菜(Brassica napus)和甘蓝(Brassica oleracea)等17个已完成基因组测序的十字花科物种基因组数据库中鉴定出18个PIN3同源基因。对这18个同源基因编码序列上游1 500bp启动子区域顺式作用元件进行预测及比对分析,结果发现,光响应、多种激素响应及胁迫响应等相关元件呈现出较大差异,其中生长素以及向地性响应相关元件具有较高的保守性。克隆普通荠菜PIN3同源基因(CbPIN3)并构建普通荠菜PIN3基因启动子的GUS报告系统CbPIN3pro::GUS转化拟南芥。与拟南芥基因表达数据库比较,荠菜启动子表达与拟南芥PIN3具有基本一致的组织表达模式,但也存在一定的组织差异,说明植株形态建成中生长素极性转运调控的差异。拟南芥和荠菜PIN3的表达差异是十字花科物种适应性进化模式的缩影。     

Quercetin Promotes Auxin Transport in Arabidopsis thaliana

Study on the role of quercentin in polar auxin transportation. Arabidopsis was cultured on medium supplemented with quercetin to observe the growth of hypocotyls, 14C-IAA transport assays were conducted to measure the auxin transport activity. The results showed that Arabidopsis mutant auxl which had been deficient in auxin influx transportion obviously recovered the ability after cultured on the medium with quercetin. The polar auxin transport was promoted by the addition of quercetin. These results indicated that quereetin could promote polar auxin transport in vivo.     

槲皮素促进拟南芥生长素极性运输的研究(英文)

Study on the role of quercentin in polar auxin transportation. Arabidopsis was cultured on medium supplemented with quercetin to observe the growth of hypocotyls,14C-IAA transport assays were conducted to measure the auxin transport activity. The results showed that Arabidopsis mutant aux1 which had been deficient in auxin influx transportion obviously recovered the ability after cultured on the medium with quercetin. The polar auxin transport was promoted by the addition of quercetin. These results indicated that quercetin could promote polar auxin transport in vivo.     

Quercetin Promotes Auxin Transport in Arabidopsis thaliana

Study on the role of quercentin in polar auxin transportation. Arabidopsis was cultured on medium supplemented with quercetin to observe the growth of hypocotyls,14C-IAA transport assays were conducted to measure the auxin transport activity. The results showed that Arabidopsis mutant aux1 which had been deficient in auxin influx transportion obviously recovered the ability after cultured on the medium with quercetin. The polar auxin transport was promoted by the addition of quercetin. These results indicated that quercetin could promote polar auxin transport in vivo.     

槲皮素促进拟南芥生长素极性运输的研究

用含有外源槲皮素的培养基种植拟南芥，探讨槲皮素对拟南芥生长素极性运输的影响。     

Auxin gradients are associated with polarity changes in trees

Models of plant growth and development propose that changes in cell polarity are mediated by gradients of the plant hormone auxin. With use of gas chromatography-mass spectrometry, we measured the redistribution of endogenous auxin in stems of quaking aspen trees (Populus tremuloides) after wounding. Persistent (lasting at least 24 hours) auxin gradients were observed in the region of the cambium where cell polarity was changing. A computer model of the auxin redistribution shows agreement with measured concentrations.     

Naturally occurring auxin transport regulators

The process of polar auxin transport, central to a plant's auxin relations, can be inhibited by a group of synthetic compounds that apparently act by binding to a plasma membrane protein known as the naphthylphthalamic acid (NPA) receptor. No endogenous ligand to the NPA receptor, capable of affecting polar auxin transport in plants, has yet been found. It is now shown that a group of flavonoids-including quercetin, apigenin, and kaempferol-can specifically compete with [(3)H]NPA for binding to its receptor and can perturb auxin transport in a variety of plant tissues and transport systems in a manner closely paralleling the action of synthetic transport inhibitors. Because the active flavonoids are widely distributed in the plant kingdom and exert their effects at micromolar concentrations approximating likely endogenous levels, they may act as natural auxin transport regulators in plants.     

水稻冠根数目多样性与生长素的关系

采用改进的水稻根系鉴定体系考察42个生态型水稻的冠根数目,发现水稻冠根数目存在多样性;从中选择2个冠根数目极端多和2个冠根数目极端少的生态型,利用定点施加生长素极性运输抑制剂NPA,以冠根数目为指标,分析冠根数目不同的生态型对NPA的敏感性,发现NPA处理导致冠根数目减少。在低浓度NPA处理时,冠根数目多的品种比冠根数目少的品种对NPA更敏感;在高浓度NPA处理时,不同生态型水稻冠根数目趋于接近。说明在不同根系类型的水稻中,生长素对冠根数目都有着重要的影响。     

三维扰动波在局部粗糙边界层中的稳定性研究

采用局部喷、吸、喷和吸组合来模拟局部粗糙壁面,数值计算获得稳定的三维边界层的基本流.在此基础上研究了三维扰动波在该基本流中的空间演化问题,讨论了局部粗糙的形式、分布结构对三维扰动波的幅值增长率及流动稳定性影响.计算结果表明:三维局部粗糙对三维扰动波的增长、涡的形成都起着激励的作用.扰动波演化产生的平均流修正及局部粗糙诱导展向速度的存在,影响着流体运动稳定性.与光滑壁面相比,三维局部粗糙作用下扰动波的传播角度与相位角发生明显变化,而不同形式的二维局部粗糙壁面边界层显示出不同的稳定特性.