Characterization of the 19 Novel Cotton FLA Genes and Their Expression Profiling in Fiber Development and in Response to Phytohormones and Salt Stress

Fasciclin-like arabinogalactan proteins(FLAs),a subclass of arabinogalactan proteins(AGPs),are usually involved in cell development in plants.To investigate the expression profiling as well

Simultaneous determination of multi endogenous phytohormones in rice tissues by GC/MS

Although at different content levels, phytohormones including auxins, gibberellins, cytokinns and ahscisic acid distribute widely over rice tissues. It has

Abiotic Stresses and Phytohormones Regulate Expression of FAD2 Gene in Arabidopsis thaliana

Modification of unsaturated fatty acid （FA） levels has been found to accompany multiple abiotic stress acclimations in many plants. Delta 12 fatty acid desaturase （FAD2） plays a critical role in the synthesis of polyunsaturated FAs in plant cells by converting oleic acid （18：1） to linoleic acid （18：2）. To better understand the relationship between polyunsaturated FAs metabolism and stress adaptation, the expression of FAD2 gene and changes in the FA compositions under various abiotic stresses and phytohormone treatments in Arabidopsis thaliana was investigated in this study. A 1 423-bp promoter of the FAD2 gene was cloned and characterized from Arabidopsis. Several putative hormone- and stress- inducible cis-elements were identified in the cloned promoter, which include salt- and pathogen-inducible GT-1 motifs, low-temperature-responsive MYC element, dehydration-responsive MYB element, and GA signaling related WRKY71OS element. To investigate the fine regulation of FAD2 gene, a recombinant FAD2 promoter-GUS construct was introduced into Arabidopsis plants. Histochemical study showed that the promoter was ubiquitously active and responsive not only to exogenous phytohormones including ABA, 24-eBL, and SA but also to darkness, temperature, salt, and sucrose stresses in Arabidopsis seedlings. Consistent with the expression change, treatments with exogenous 24-eBL, ABA, SA, and NaCl resulted in reduction in polyunsaturated FAs in Arabidopsis seedlings. These findings suggest that the FAD2 gene with a wide variety of putative response elements in its promoter is responsive to multiple phytohormones and abiotic stresses and therefore may play an important role in stress responses of Arabidopsis during plant growth and seed development.

Regulation of phytohormones on root primordium initiation and adventitious root formation in the etiolated shoots of Paeonia suffruticosa'Yinfen Jinlin'

Tree peony is well known and sought after for its large, colorful flowers. Its propagation is via vegetative methods. Mech- nisms of the adventitious rooting and the regulation of rooting processes are the principles and techniques of plant propagation and improvement. Microstructures and fluctuations of phytohormones in the adventitious rooting were studied with the etiolated soft- wood shoots of Paeonia suffkuticosa ＇Yinfen Jinlin＇. There are no pre-primordia in the shoots of the cultivar. Adventitious roots are produced in five stages： shoot selection, primordium initiation, primordium growth, conducting tissue differentiation and root protru- sion. Primordia initiated in the cortex. The contents of the endogenous hormones, IAA, ABA and GA, were 5.842, 0.873 and 1.043 nmol·g^-1 FW on the bases of shoots, respectively. CTKs which included isopentenyl adenine （iPA）, zeatin riboside （ZR） and dihy- drozeatin riboside （DHZR） were 0.949, 0.695 and 2.034 nmol·g^-1 FW, respectively. DHZR is active among CTKs. The ratio of IAA to GA, CTK and ABA clearly increased at the stage of primordium initiation, while they showed low levels at the stages of primor- dium growth. The ratios were restored at the shoot levels at the stage of root protrusion. IBA provoked primordia initiation in the cortex, the vascular cambium, the pith and even in the callus induced on the base of shoots. ]AA levels in the treated shoots increased gradually to its highest level （three times of control） at the stage of conducting tissue differentiation. The ratios of IAA to GA, CTK and ABA clearly decreased at the stage of primordium initiation. The ratio of IAA to ABA is regulated at 10：1.

Cloning and Expression Analysis of an AP2/ERF Gene and Its Responses to Phytohormones and Abiotic Stresses in Rice

Ethylene response factors （ERFs） play important roles in response to plant biotic and abiotic stresses. In this study, a gene encoding a putative AP2/ERF domain-containing protein was isolated by screening a SSH cDNA library from rice and designated as Oryza sativa AP2/ERF-like protein （OsAP2LP） gene. OsAP2LP is 1491 bp in length, interrupted by seven introns, and encodes a putative protein of 348 amino acids. Temporal and spatial expression analysis showed that the OsAP2LP gene was preferentially expressed in roots, panicles, mature embryos and seeds in rice. Real-time quantitative PCR analysis indicated that the expression levels of the OsAP2LP gene were increased under the treatments of drought and gibberellin but decreased under the treatments of low temperature, salt, abscisic acid （ABA） and zeatin. Taken together, these results suggest that OsAP2LP might be involved in stress responses, and probably plays roles as a transcription regulator when plants response to cold, salt and drought stresses through ABA and gibberellin pathways.

Strigolactones interact with other phytohormones to modulate plant root growth and development

Strigolactones(SLs),which are biosynthesized mainly in roots,modulate various aspects of plant growth and development.Here,we review recent research on the role of SLs and their cross-regulation with auxin,cytokinin,and ethylene in the modulation of root growth and development.Under nutrientsufficient conditions,SLs regulate the elongation of primary roots and inhibit adventitious root formation in eudicot plants.SLs promote the elongation of seminal roots and increase the number of adventitious roots in grass plants in the short term,while inhibiting lateral root development in both grass and eudicot plants.The effects of SLs on the elongation of root hairs are variable and depend on plant species,growth conditions,and SL concentration.Nitrogen or phosphate deficiency induces the accumulation of endogenous SLs,modulates root growth and development.Genetic analyses indicate cross-regulation of SLs with auxin,cytokinin,and ethylene in regulation of root growth and development.We discuss the implications of these studies and consider their potential for exploiting the components of SL signaling for the design of crop plants with more efficient soil-resource utilization.

Effect of ploidy level on expression of lycopene biosynthesis genes and accumulation of phytohormones during watermelon(Citrullus lanatus) fruit development and ripening

The difference between lycopene and phytohormone levels among diploid, triploid and tetraploid plants of two watermelon cultivars during fruit growth and ripening was studied. The expression pattern of five genes（phytoene synthase（PSY1）, phytoene desaturase（PDS）, ζ-carotene desaturase（ZDS）, carotenoid isomerase（CRTISO）, and lycopene β-cyclase（LCYB）） was analyzed in details. In red-fleshed cultivar Mimei, lycopene content increased rapidly from 25 to 35 days after pollination（DAP）, and then decreased at 40 DAP. Triploid and tetraploid fruit had higher levels of lycopene than diploid. Moreover, triploid tended to contain more lycopene than tetraploid during fruit growth and ripening stages. However, little amount of lycopene（0–2 mg kg–1 fresh weight（FW）） in yellow-fleshed cultivar Huangmei was found during all fruit development stages. In Mimei, transcript level of PSY1 was generally higher than the other four genes, and LCYB gene expression was the lowest among all five genes being tested. PSY1, CRTISO and LCYB genes showed higher transcript levels in polyploid than in diploid fruit. By contrast, in Huangmei, transcript level of LCYB was not the lowest, but only lower than that of PSY1. PSY1, CRTISO and LCYB genes showed higher expression levels in diploid than in polyploid fruit. In Mimei, the negative correlation between gibberellane（GA） content and lycopene accumulation was determined in all three different ploidy fruits, while a positive correlation was observed between abscisic acid（ABA） content and lycopene accumulation only in diploid watermelon. These results indicated that different lycopene contents in different ploidy watermelons is regulated by the differential transcription expression of the lycopene metabolic genes and phytohormones.

The regulatory network behind maize seed germination: Effects of temperature, water, phytohormones, and nutrients

Seed germination is the process by which an organism grows from a seed. It requires suitable conditions and environmental factors. Maize is one of the most important crops worldwide. Germination influences both final maize yield and quality. Seed germination is regulated by a complex gene network. It is also influenced by endogenous(phytohormones and nutrients) and exogenous(temperature and water)inputs, involving molecular networks only partly identified to date. This review describes current understanding of the influence of temperature, water, phytohormones, and nutrients in regulating maize seed germination, and indicates knowledge gaps that should be addressed.

Interactive Effects of Drought Stress and Phytohormones or Polyamines on Growth and Yield of Two M(<i>Zea maize</i>L) Genotypes

Two maize genotypes (Nefertiti and Bashaier) were picked up from nine maize genotypes during the early vegetative growth (25 days) to be cultivated in open field upon the crop yield under the different drought stress levels (90,70,50,30) or under the interaction effect of drought stress and phytohormones or polyamines. According to the data of growth criteria, the maize genotype Nefertiti was found to be the most drought sensitive genotype, while the genotype Bashaier was found to be the most drought resistant genotype. Additionally while the photosynthetic pigments remained more or less unchanged in genotype Bashaier, their biosynthesis destroyed earlier in the drought sensitive genotype (Nefertiti). Also while the genotype Bashaier absorbed and accumulated a sufficient amount of mono and divalent cations (K+, Ca++ and Mg++), the genotype Nefertiti did not. Accordingly while the genotype Bashaier gave a crop yield up to 50% field capacity, the genotype Nefertiti gave a crop yield only up to 70% field capacity and failed to give a crop yield beyond this level. The interaction effect of drought stress and phytohormones and polyamines improved the all above characteristics. Interestingly each of these activators considerably improved the production of crop yield only in genotype Bashaier specially polyamines they produced more than 60% field capacity and at the level of 30% field capacity (the level which did not give crop yield in this genotype). However, phytohormones in generally did not make an important effect on the crop yield in genotype Nefertiti although they improved the dry matter production during the vegetative stages. Such situation seemed to be complicated and borne many questions to be studied in the future.

Detection of seven phytohormones in peanut tissues by ultra-highperformance liquid chromatography-triple quadrupole tandem mass spectrometry

Development of highly sensitive and reliable method for detection of phytohormones is of great significance to study plant hormones and agricultural production.In this study,an ultra-high-performance liquid chromatography-mass spectrometry/mass spectrometry method was established for separation and quantification of trans-zeatin,trans-zeatin riboside,gibberellin A3,indol-3-acetic acid,salicylic acid,abscisic acid,and jasmonic acid(JA) without any label.The sepa ration was performed on an Agilent Explus Plus C18 column by using methanol and water as mobile phases with gradient elution.The target compounds were confirmed and quantified by mass spectrum via positive electrospray ionization for trans-zeatin,transzeatin riboside,indole-3-acetic acid,and via negative electrospray ionization for gibberellin3,salicylic acid,abscisic acid,and JA.The limits of detection ranged from 0.0127 ng L^-1 for gibberellin A3(GA3) to 33.26 ng L^-1 for JA and were lower than the currently reported values in literature.The proposed method was applied for qualitative and quantitative analyses of phytohormones in peanut gynophores and pods.The recoveries of the spiked phytohormones ranged from 80.20 to102.56%.The contents of seven endogenous hormones varied specifically in different development stages of peanuts.This study provides a highly sensitive and selective detection method for hormones and elucidates the growth and development of the gynophore and peanut fruit,which are controlled by seven endogenous hormones.

Expression and functional analyses of the mitogen-activated protein kinase (MPK) cascade genes in response to phytohormones in wheat ( Triticum aestivum L.)

Mitogen-activated protein kinase （MPK） cascades consist of a set of kinase types （MPKKKs, MPKKs, MPKs） to establish conserved signal-transducing modules mediating plant growth, development as well as responses to internal and external cues. In this study, the expression patterns of six MPKKK, two MPKK, and 11 MPK genes in wheat in responses to external treatments of phytohormones, including naphthylacetic acid （NAA）, abscisic acid （ABA）, 6-benzyladenine （6-BA）, gibber- ellin （GA3）, salisylic acid （SA）, jasmonic acid （JA）, and ethylene （ETH）, were investigated. Expression analysis revealed that several of the MPK cascade genes are responses to the external phytohormone signaling. Of which, TaMPKKKA;3 is induced by 6-BA and NAA while TaMPK4 repressed by ETH, GA3, SA, and JA; TaMPKKKA, TaMPKKKA;3 and TaMPK1 are down-regulated by ETH and GA3whereas TaMPK9 and TaMPK12 repressed by ETH and JA in addition that TaMPK12 also repressed by GA3; TaMPK12;1 is down-regulated by ABA, GA3 and SA while TaMPK17 repressed by all exogenous phytonormones examined. TaMPK4, a MPK type gene previously characterized to mediate tolerance to phosphate （Pi） deprivation, was functionally evaluated for its role in mediation of responses of plants to exogenous GA3, ETH, SA, and JA. Results indicated that overexpression and antisense expression of TaMPK4 in tobacco dramatically modify the growth of seedlings upon treatments of GA3, SA and JA, in which the overexpressors behaved deteriorated growth feature whereas the seedlings with antisense expression of TaMPK4 exhibited improved seedling phenotype. The growth behaviors in lines overexpressing or antisensely expressing TaMPK4 are closely associated with the biomass and the corresponding hormone-associated parameters. These results demonstrated that TaMPK4 acts as a critical player in mediating the phyto- hormone signaling. Our findings have identified the phytohormone-responsive MPK cascade genes in wheat and provided a connection between the phytohormone-mediated responses and the MPK cascade pathways.

Interplay of phytohormones and epigenetic regulation:A recipe for plant development and plasticity

Both phytohormone signaling and epigenetic mechanisms have long been known to play crucial roles in plant development and plasticity in response to ambient stimuli.Indeed,diverse signaling pathways mediated by phytohormones and epigenetic processes integrate multiple upstream signals to regulate various plant traits.Emerging evidence indicates that phytohormones and epigenetic processes interact at multiple levels.In this review,we summarize the current knowledge of the interplay between phytohormones and epigenetic processes from the perspective of phytohormone biology.We also review chemical regulators used in epigenetic studies and propose strategies for developing novel regulators using multidisciplinary approaches.

果实采后软化机制研究进展

采后果实在经过储藏运输等一系列过程后会发生软化现象,而软化现象产生的原因有很多,例如由于细胞壁代谢相关酶活性的作用,使得细胞壁的物质成分、结构等发生改变;也可能是由于果实成熟后相关物质的变化以及受到植物激素的调控,进而促进果实成熟软化。本文综述了采后果实软化产生的原因,包括植物激素合成以及与受体结合进而促进果实软化、相关转录因子对果实软化的调控和果实软化相关的细胞壁代谢与碳水化合物代谢等途径,以期为探究采后果实软化机制提供参考。

种子休眠与萌发调控的研究进展

休眠使植物种子能够为萌发安排时间,直到环境条件变得有利于幼苗的存活与生长。种子的休眠特性具有重要的生态适应性意义和显著的农业价值。植物激素脱落酸(ABA)和赤霉素(GA)是种子休眠与萌发的关键因素,处于休眠状态的成熟种子含有高水平的ABA和低水平的GA;ABA诱导和维持种子休眠,而GA拮抗ABA的作用和促进种子萌发。萌发延迟-1 (DOG1)是种子休眠的主要调控因子,与ABA协同作用延迟萌发。DOG1通过与PP2C ABA过敏感萌发(AHG1/AHG3)结合以增强ABA的信号转导,以及抑制AHG1的作用以增加ABA的敏感性和强加种子休眠。印记基因在受精前后受到表观遗传机制的调控,与种子休眠的建立与释放密切相关。近年来,种子休眠的调控研究取得了显著的进展。本文综述了植物激素ABA和GA对种子休眠与萌发的控制, DOG1调控种子休眠的作用机制,以及种子休眠与萌发的表观遗传调控,并提出了在本领域需要进一步研究的科学问题,以期为深入理解种子休眠与萌发的分子机制、抗穗萌发育种以及促进休眠种子的萌发提供参考。

赤霉素及二氢茉莉酸丙酯对抑制温州蜜柑果实浮皮的影响

为探究抑制果实浮皮的方法及赤霉素(GA_(3))与二氢茉莉酸丙酯(PDJ)抑制浮皮发生的机制,本研究以完熟栽培温州蜜柑宫川为试验材料,通过喷施钙或GA_(3)与PDJ,研究其对果实浮皮指数以及果实品质的影响,并分析GA_(3)与PDJ处理后果皮的细胞壁结构、细胞壁物质含量、相关水解酶活性、果皮激素含量及相关基因表达量的变化。结果表明,各处理均能降低果实浮皮指数,其中采前喷施2次GA_(3)和PDJ后果实浮皮指数始终维持在较低水平,且该处理条件下果实外观及内在品质无明显变化。同时,GA_(3)与PDJ处理下调了CitCx、CitPME等基因表达量,降低了果胶酯酶(PME)和纤维素酶(Cx)的活性,提高了果皮中原果胶和半纤维素含量,延缓了纤维素含量下降并增加了果实硬度,并且降低了果皮细胞膜脂过氧化程度。喷施GA_(3)与PDJ后果皮中乙烯合成量下降而生长素含量上升,CitACO基因表达下调,而CitETR1及CitIAA27表达上调。综上,采前喷施2次GA_(3)与PDJ是防治完熟栽培温州蜜柑浮皮的最佳方法。GA_(3)与PDJ通过抑制细胞壁结构物质降解,降低膜脂过氧化程度,同时抑制乙烯合成并降低果皮细胞对乙烯的敏感性,提高果皮生长素(IAA)含量并抑制果皮衰老,从而抑制浮皮的发生。本研究结果为开发控制浮皮技术及揭示柑橘果实浮皮发生机制提供了实践与理论参考。

激素对圆齿野鸦椿种子萌发的影响

【目的】探究激素在圆齿野鸦椿种子萌发中的作用及其与活性氧的关系,为圆齿野鸦椿种子破眠技术和种苗高效繁育技术提供理论依据。【方法】以自然层积210 d的圆齿野鸦椿种子为试验材料,去除外部硬质种壳,进行为期12 d的萌发试验,测定纯水、不同浓度的赤霉素(GA_(3))(20、40和60μmol/L)和脱落酸(ABA)(10、20和30μmol/L)处理下萌发率及活性氧、抗氧化物质、植物激素、可溶性糖和可溶性蛋白含量的变化,并观察记录种子的萌发形态。【结果】纯水处理萌发率最终达77.8%,GA_(3)处理萌发率最高可达82.2%,ABA处理萌发率最终均未达50.0%,而保留硬质种皮纯水处理的种子萌发率仅17.8%。3种浓度的GA_(3)处理均可有效缩短圆齿野鸦椿种子萌发率达50.0%的时间(T_(50)),促进根茎生长,但其最终萌发率均与纯水处理无显著差异(P>0.05);ABA处理浓度越高,对圆齿野鸦椿种子抑制萌发作用越强。相关分析显示,在萌发的第8和12 d,萌发率与GA_(3)、油菜素内酯(BR)和茉莉酸(JA)呈显著正相关(P<0.05,下同),且超氧阴离子(O_(2)^(-)·)与BR和JA含量呈显著负相关,与过氧化氢酶(CAT)、ABA、ABA/GA_(3)均呈显著正相关。【结论】添加GA_(3)可有效缩短圆齿野鸦椿种子萌发率达50%的时间,促进根茎生长,O_(2)^(-)·与ABA的积累对种子萌发存在抑制作用,BR和JA对种子萌发的促进作用可能与对O_(2)^(-)·的清除有关。

‘红地球’葡萄VvARF18功能分析

【目的】生长素响应因子ARF是生长素信号转导途径中的重要调控因子,在植物生长发育和各类生理过程中发挥着重要作用。分析‘红地球’葡萄VvARF18启动子、异源表达、内源激素含量及其对激素响应的表达,以探究VvARF18在‘红地球’葡萄生长素(IAA)信号转导途径及花芽分化进程中的作用机理。【方法】以设施‘红地球’葡萄花芽为试验材料,通过同源克隆获得VvARF18序列,利用在线数据库PLACE分析启动子的顺式作用元件。以pCAMBIAI2300植物表达载体为基础,通过双酶切和同源重组法构建植物超表达载体pC2300-VvARF18。采用电击法将重组载体pC2300-VvARF18转化至根癌农杆菌GV3101菌株中,以本氏烟草叶片为外植体,通过农杆菌介导的愈伤组织转化法转入烟草中,经PCR检测获得阳性转基因幼苗。利用实时荧光定量PCR(qRT-PCR)对转VvARF18烟草株系表达水平进行分析,筛选出高表达量的转基因株系培养至T_(3)代,并分别进行IAA和GA_(3)处理,以分析VvARF18的表达情况。通过酶联免疫法测定转基因烟草花芽和叶片中的IAA、GA、ABA、CTK含量。【结果】‘红地球’葡萄VvARF18位于第13条染色体,含有3个外显子和2个内含子。VvARF18启动子区域存在多种光响应、植物激素响应和逆境响应的顺式作用元件。表型分析发现,转基因烟草的花芽分化进程快于野生型烟草。qRT-PCR结果显示,VvARF18在转基因烟草花芽发育的4个时期中呈先上升后下降的表达趋势,且S3时期表达量达到最高。转基因烟草植株花芽和叶片中IAA、CTK、GA和ABA测定结果表明,转基因烟草花芽和叶片中4种植物激素的含量均高于野生型植株,其中GA/IAA在转基因烟草花芽发育的4个时期中变化趋势与VvARF18表达趋势相一致。转基因烟草植株经IAA和GA_(3)处理后,VvARF18的表达量随IAA处理浓度的增高而降低,也随GA_(3)处理时间的延长而降低。【结论】葡萄Vv ARF18负调控生长素参与植物花芽分化进程,可能与赤霉素信号转导途径中的关键因子相互作用协同调控植物花芽中的激素水平,对植物花芽分化具有促进作用。

甘蓝型油菜REVEILLE家族鉴定及诱导表达分析

【目的】REVEILLE家族基因具有重要生物学功能,而在甘蓝型油菜(Brassica napus L.)中该家族基因研究较少,深入认识甘蓝型油菜中RVE家族基因功能及其与非生物胁迫的关系。【方法】利用生物信息学方法,在甘蓝型油菜、白菜(Brassica rapa)和甘蓝(B.oleracea)中分别鉴定到33、16和16个RVE基因,并对其系统进化、染色体定位、基因结构和理化性质以及启动子顺式元件进行分析。【结果】所有的RVE蛋白被分为两个亚家族。33个BnaRVE分别定位在18条A亚基因组的染色体和15条C亚基因组的染色体上。大部分成员属于较稳定的疏水蛋白;多数Ka/Ks值小于1,说明该家族受到强烈的纯化选择作用。基因结构变异较大,内含子数目在4-11之间。共线性分析结果表明,甘蓝型油菜和拟南芥、白菜、甘蓝存在大量的同源基因。大部分甘蓝型油菜RVE家族成员在子叶和叶都有表达且表达量最多。BnaRVE启动子上含有大量与激素和生物逆境相关的元件,通过定量PCR分析,4个BnaRVE在ABA与MeJA诱导和低温胁迫下的表达量显著上调。【结论】在甘蓝型油菜基因组中鉴定出33个BnaRVE家族成员。不同基因在不同发育时期和不同组织中表现出不同的表达模式。不同基因对各种胁迫存在响应,且表达模式不一。RVE家族成员对ABA、MeJA和冷胁迫具有正向响应功能。

槲树不同外植体愈伤组织诱导及继代培养研究

【目的】以槲树(Quercus dentata)的根与叶为外植体,以期筛选出愈伤组织诱导和继代培养的适宜条件,为槲树组培快繁体系的建立提供支撑。【方法】在WPM、MS、1/2MS三种培养基中,加入不同浓度的NAA和6-BA,以槲树幼苗根与叶为外植体诱导愈伤组织,记录、分析和比较不同条件下的诱导率。再将根诱导后的愈伤组织接种于WPM培养基中,添加不同浓度的2,4-D和6-BA进行愈伤组织的增殖,计算和比较增殖系数。【结果】叶片诱导愈伤组织的最佳培养基为MS+NAA 1.0 mg/L+6-BA 0.5 mg/L。根诱导愈伤组织的最佳的培养基为WPM+NAA 2.0 mg/L+6-BA 1.0 mg/L。经比较,以根作为外植体的诱导率高于叶片。愈伤组织增殖的最佳培养基为WPM+2,4-D 1.2 mg/L+6-BA 0.9 mg/L。【结论】筛选出了最适合槲树愈伤组织诱导和增殖的培养基配方,为槲树组培快繁体系的建立奠定了基础。