植物开花光周期反应的分子调控机制

植物开花时间受到日照长短季节性变化的调节,拟南芥和水稻中与光周期反应相关基因的分离,使人们得以认识植物开花光周期反应的分子调控机制。植物感知日照长短的变化主要由CONSTANS(CO)基因的表达所控制。CO能够将光信号与生物钟信号整合,调节开花基因FLOWERING LOCUS T(FT)的表达,并最终控制植物的开花时间。本文对这一研究的最新进展进行了综述。     

不同光周期条件下大豆生育期主基因的效应

以大豆生育期近等基因系为材料, 比较12 h短日照(SD)及16 h长日照(LD)条件下E1/e1、E2/e2、E3/e3、E4/e4、E5/e5、E7/e7等6对生育期相关主基因的效应。结果表明, 在大多数生育期基因型中, 显性位点延迟大豆的开花期和成熟期, 隐性位点提早开花期和成熟期。同一基因在不同遗传背景下的效应值不同, 显性位点可增强其他基因的效应, 说明各基因间存在互作。生育期基因的效应受光周期影响很大, 长日照可增强大豆生育期相关基因的效应, 短日照则相反。此外, 光周期对基因效应的影响因发育阶段不同而变化, 其中, E1基因在大豆营养生长阶段、E4基因在生殖生长阶段受光周期影响较大, 而E3基因在营养生长和生殖发育阶段均受光周期的严格调控。不同光照条件下生育期基因效应的分析结果, 可为不同生态区大豆品种生育期性状的定量设计提供依据。     

不同生态类型大豆品种光周期反应的鉴定

通过设置短日照(12h)和长日照(16h)两种光照处理,对58个近年育成的不同生态类型大豆品种(系)进行光周期反应鉴定.结果表明.大豆光周期反应敏感性强弱依次为南方夏大豆、南方春大豆、黄淮海夏大豆、北方春大豆,品种的光周期反应敏感性随着主产地纬度的降低而增强;本试验建立了一种以短日开花促进率为评价指标的光周期反应敏感性的鉴定方法,该方法准确、简便、周期短、成本低廉.     

中科院昆明植物所等在植物开花调控研究中取得新进展

<正>在拟南芥中,长日照条件诱导开花启动因子Flowering Locus T(FT)的表达来加速植物开花。光周期条件对FT的激活主要依赖于转录因子CONSTANS(CO)的活性,对CO的转录水平、蛋白质稳定性以及生物钟的调控是植物能够响应光周期并诱导植物成花的关键机制。ABI5结合蛋白2     

以光周期处理与分期播种试验综合鉴定大豆品种的光温反应

设置短日照(12 h)和长日照(16 h)两种光周期处理,并以春播模拟低温、夏播模拟高温条件,形成长日+低温、长日+高温、短日+低温、短日+高温4种光温组合。2007年对近年育成的10个北方春大豆[Glycine max (L.) Merr.]品种(系)和18个黄淮海夏大豆品种(系)进行了光温反应特性鉴定。2008年对50份材料进行了光周期反应鉴定。结果表明,不论在低温(春播)还是高温(夏播)条件下,短日照均加快大豆的发育进程,导致开花提前;不论在长日照还是短日照条件下,高温均减少出苗至初花的日数。光周期和温度对大豆的发育存在明显的互作,随着温度的升高,短日照促进大豆发育的效应有所加强;随着日照的缩短,高温加快发育的作用也有所增大。供试大豆品种生态类型在光周期反应敏感度(PRS)、温度反应敏感度(TRS)及光温综合反应敏感度(PTCRS)等方面均存在显著差异。北方春大豆品种的上述3个指标均小于黄淮海夏大豆品种,但前者在不同光照条件下的温度反应敏感度差值和在不同温度条件下的光周期反应敏感度差值均较后者高,说明北方春大豆品种光温互作效应较强。     

光周期途径成花关键基因GIGANTEA和CONSTANS的研究进展

GIGANTEA(GI)和CONSTANS(CO)在植物光周期开花诱导途径中起促进作用。GI和CO基因受生物钟调控,表达量在一天内呈规律性变化。在长日照条件下,GI和CO基因促进拟南芥开花,但在短日照条件下,对拟南芥开花时间的影响不大。GI是影响生物节律钟输出和植物进行正常生命活动的重要基因,编码一个核蛋白,GI正调控CO基因的表达。CO是编码一个B-box锌指蛋白,是监测日照长度的重要元件,并激活FT基因表达,诱导植物开花。本综述概括了近年来GI和CO基因的结构和功能,为GI和CO基因的深入研究提供参考。     

一个 T-DNA 插入突变体的分子鉴定及表达分析

突变体在水稻功能基因组研究中具有重要的作用。对水稻OsFCA位点的插入突变体进行了分子鉴定,证实此突变体为纯合突变体,并且发现突变体与野生型植株相比,抽穗期明显延迟。通过RT-PCR结果分析表明, T-DNA插入的突变体植株中OsFCA基因完全不表达。另外,在短日照条件下,对水稻成花相关的2个重要基因Hd1和Hd3a的RT-PCR分析表明,在野生型植株中,2个基因的表达量都明显高于突变体植株,尤其是在夜间的表达量相差较为明显。说明OsFCA在短日照条件下通过正向调控Hd1和Hd3a的表达促进水稻的开花。     

大豆几种光周期处理效应的植物激素解析

研究了大豆光照后效应、开花逆转、光周期对源库关系的调控、摘荚后光周期反应等现象中,内源激素的变化及几种外源生长物质对大豆发育的效应。结果表明,开花前对超早熟大豆品种东农36进行短日处理,明显加快开花后发育速度,降低叶片中的ABA和ZRs含量;幼苗期(VE-V2)对晚熟品种自贡冬豆进行l0 d左右的短日处理,尔后置15 h长     

大豆生物钟基因GmLNK1/2、GmRVE4/8和GmTOC1 CRISPR/Cas9组织表达分析及敲除靶点的鉴定

生物钟基因能够参与调控植物的整个生命进程,对提高作物产量具有重要的作用。LNK1(NIGHTLIGHTINDUCIBLE AND CLOCK-REGULATED 1)、LNK2、RVE4 (REVEILLE 4)、RVE8 (REVEILLE 8)和TOC1 (TIMING OF CAB EXPRESSION1)是植物中重要的生物钟基因。本研究利用BLAST同源比对和进化树分析的方法分别鉴定AtLNK1、AtLNK2、AtRVE4、AtRVE8和AtTOC1在大豆中的同源基因,通过qRT-PCR实验证明这些生物钟基因在大豆根、茎、叶等组织中均有表达。成功构建这些基因的CRISPR/Cas9敲除载体,并利用大豆根毛转化体系成功鉴定出13个基因的CRISPR/CAS9有效靶点。为进一步获得稳定的大豆突变体材料及研究其生物钟基因的功能提供了理论基础。     

大豆品种自贡冬豆花芽分化及开花逆转过程的形态解剖学研究

研究了光周期反应敏感的晚熟大豆[Glycine max (L.) Merr.]品种自贡冬豆在正常花芽分化和开花逆转过程中的解剖学特征。光周期处理包括连续短日照（SD, 12 h）、连续长日照（LD, 16 h）和13 d短日后转入长日(SD13d-LD)3种。结果表明, 自贡冬豆在连续短日条件下可正常开花结实;经13 d短日照处理后移至长日照下约50％的植株发生开花逆转,另外50％的植株形成短的顶端花序;在连续长日照下保持营养生长。短日照不仅促进大豆的生殖发育, 而且加快出叶速度。短日处理3 d基部叶腋开始分化花芽;13 d顶端分生组织开始分化花序,19 d顶端花序分化结束,29 d植株开花。SD13-LD处理,在移至长日照的最初14 d内,顶端分生组织继续分化花原基,但分化速度比连续短日处理慢,分化出的花芽数目少。长日处理20 d（出苗后33 d）左右,约50％植株的顶端分生组织逆转到营养器官的分化。在连续长日条件下,顶端分生组织一直分化叶片。还讨论了叶片和花器官的同源性。     

Location of a high-lysine gene and the DDT-resistance gene on barley chromosome 7

Summary The high-lysine gene in Risø mutant 1508 conditions an increased lysine content in the endosperm via a changed protein composition, a decreased seed size, and several other characters of the seed. The designation lys3a, lys3b, and lys3c, is proposed for the allelic high-lysine genes in three Risø mutants, nos 1508, 18, and 19. Linkage studies with translocations locate the lys3 locus in the centromere region of chromosome 7. A linkage study involving the loci lys3 and ddt (resistance to DDT) together with the marker loci fs (fragile stem), s (short rachilla hairs), and r (smooth awn) show that the order of the five loci on chromosome 7 from the long to the short chromosome arm is r, s, fs, lys3, ddt. The distance from locus r to locus ddt is about 100 centimorgans.     

Biological Activity and Quantification of Suspected Allelochemicals from Alfalfa Plant Parts

Autotoxicity restricts reseeding of alfalfa (Medicago sativa L.) after alfalfa until autotoxic chemical(s) breaks down or is dispersed into external environments. A series of aqueous extracts from leaves, stems, roots and seeds of alfalfa ‘Vernal’ were bioassayed against alfalfa seedlings of the same cultivar to determine their autotoxicity. The highest inhibition was found in the extracts from the leaves. Extracts at 40 g dry tissue l^?1 from alfalfa leaves were 15.4, 17.5 and 28.7 times more toxic to alfalfa root growth than were those from roots, stems and seeds, respectively. A high‐performance liquid chromatography (HPLC) analysis with nine standard compounds showed that the concentrations and compositions of allelopathic compounds depended on the plant parts. In leaf extracts that showed the most inhibitory effect on root growth, the highest amounts of allelochemicals were detected. Among nine phenolic compounds assayed for their phytotoxicity on root growth of alfalfa, coumarin, trans‐cinnamic acid and o‐coumaric acid at 10^?3 m were most inhibitory. The type and amount of causative allelochemicals found in alfalfa plant parts were highly correlated with the results of the bioassay, indicating that the autotoxic effects of alfalfa plant parts significantly differed.     

Simultaneous Determination of Four Phenolic Acids in Radix Salviae Miltiorrhizae Formula Granules by QAMS

[Objectives]This study aimed to establish a QAMS(quantitative analysis of multi-components by single-marker)method for simultaneous determination of four phenol...     

Changes in Seed Yield and Quality with Maturity in Onion (Allium cepa L., cv. 'Early Cream Gold')

Development of onion (Allium cepa L., cv. ‘Early Cream Gold’) seed under cool climate conditions in Tasmania, Australia occurred over a longer duration than previously reported, but similar patterns of change in yield components were recorded. In contrast to previous studies, umbel moisture content declined from 85 to 67 % over 57 days while seed moisture content decreased from 85 to 31 %. Seed yield continued to increase over the duration of crop development, with increasing seed weight compensating for seed loss resulting from capsule dehiscence in the later stages of maturation. Germination percentage was high and did not vary significantly from 53 to 77 days after full bloom (DAF), but mean germination time declined and uniformity of germination increased significantly over the same time period. The percentage abnormal seedlings declined with later harvest date, resulting in highest seed quality at 77 DAF. The results of this study suggest that the decision to harvest cool climate onion seed crops before capsule dehiscence will result in a loss of potential seed yield and quality.     

Pollen and pollination experiments. III. The viability of apple and pear pollen as affected by irradiation and storage

Summary Apple and pear pollen was irradiated with doses of 0, 50, 100, 250 and 500 krad (gamma rays) and stored at 4°C and 0–10% r.h. From the in-vitro germination percentages an average LD 50 dose of about 220 krad was estimated. For both irradiated and untreated pollen a close and corresponding lineair relationship existed between germination percentage and pollen tube growth.Irradiated pollen was much more sensitive to dry storage conditions than untreated pollen, resulting in less germination and more bursting. Apparently, irradiation caused the pollen cell membrane to lose its flexibility faster than normal. Rehydration of dry-stored, irradiated pollen in water-saturated air restored germination percentages up to their initial levels. The importance of this procedure in germination trials is stressed.     

Water Extraction Process of Chinese Herbal Compound Man Gan Ning

[Objectives]To optimize the water extraction process of Chinese Herbal Compound Man Gan Ning and establish a method for its extraction and content determination...     

Present status and future strategy in breeding faba beans (Vicia Faba L.) for resistance to biotic and abiotic stresses

Progress is being made, mainly by ICARDA but also elsewhere, in breeding for resistance to Botrytis, AScochyta, Uromyces, and Orobanche; and some lines have resistance to more than one pathogen. The strategy is to extend multiple resistance but also to seek new and durable forms of resistance. Internationally coordinated programs are needed to maintain the momentum of this work.Tolerance of abiotic stresses leads to types suited to dry or cold environments rather than broad adaptability, but in this cross-pollinated species, the more hybrid vigor expressed by a cultivar, the more it is likely to tolerate various stresses.     

Optimization of Extraction Technology and Determination of Content of Total Phenols of Leaves in Acanthopanax giraldii Harms

[Objectives] To determine the optimum extraction technology for total phenols of leaves in Acanthopanax giraldii Harms.[Methods]The single factor test and ortho...     

Cytoplasmic male sterility,resistance to gall mite and mildew,and season of leafing out in black currants

Summary Cytoplasmic male sterility (cms) is described in the F₁ hybrids Ribes × carrierei (R. glutinosum albidum × R. nigrum) and R. sanguineum × R. nigrum. In backcrosses to R. nigrum, progenies with R. glutinosum cytoplasm were either all male sterile, or segregated for full male fertility (F) and complete (S) and partial (I) male sterility. Ratios of F:I+S suggested that two linked genes controlled cms, F plants being dominant for one (Rf ₁) and recessive for the other (Rf ₂).Segregation for cms in relation to three linded genes, Ce (resistance to the gall mite, Cecidophyopsis ribes), Sph ₃(resistance to American gooseberry mildew, Sphaerotheca mors-uvae) and Lf ₁(one of two dominant additive genes controlling early season leafing out) indicated that Rf ₁and Rf ₂were in this linkage group. The gene order and approximate crossover values appeared to be: % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXafv3ySLgzGmvETj2BSbqef0uAJj3BZ9Mz0bYu% H52CGmvzYLMzaerbd9wDYLwzYbItLDharqqr1ngBPrgifHhDYfgasa% acOqpw0xe9v8qqaqFD0xXdHaVhbbf9v8qqaqFr0xc9pk0xbba9q8Wq% Ffea0-yr0RYxir-Jbba9q8aq0-yq-He9q8qqQ8frFve9Fve9Ff0dme% aabaqaciGacaGaamqadaabaeaafaaakeaacaWGdbGaamyzamaamaaa% baGaaiiiaiaacccacaGGWaGaaiOlaiaacgdacaGG0aGaaiiiaiaacc% caaaGaaiiiaiaacccacaGGGaGaamOuaiaadAgaliaaigdakmaamaaa% baGaaiiiaiaacccacaGGGaGaaiiiaiaaccdacaGGUaGaaiOmaiaacs% dacaGGGaGaaiiiaiaacccacaGGGaGaaiiiaaaacaWGsbGaamOzaSGa% aGOmaOWaaWaaaeaacaGGGaGaaiiiaiaacccacaGGGaGaaiiiaiaacc% cacaGGGaGaaiiiaiaacccaaaGaamitaiaadAgaliaaigdakmaamaaa% baGaaiiiaiaacccacaGGGaGaaiiiaiaacccacaGGGaGaaiiiaiaacc% cacaGGGaGaaiiiaiaacccacaGGGaaaaiaadofacaWGWbGaamiAaSGa% aG4maaaa!6E4D!\[Ce\underline { 0.14 } Rf1\underline { 0.24 } Rf2\underline { } Lf1\underline { } Sph3\]. Crossover values of 0.36 for Ce-Lf ₁, and 0.15 for Lf ₁-Sph ₃were estimated from the relative mean differences in season of leafing out between seedlings dominant and recessive for Ce and Sph ₃.It is suggested that competitive disadvantage of lf ₁-carrying gametes and/or zygotes at low temperatures may be implicated in the almost invariable deficit of plants dominant for the closely linked mildew resistance allele Sph ₃. Poor performance of lf ₁- (and possibly lf ₂-) carrying gametes and young zygotes during periods of low temperature at flowering might also account for the liability of some late season cultivars and selections to premature fruit drop (running off).     

Screening techniques and sources of resistance to parasitic angiosperms

Parasitic angiosperms cause great losses in many important crops under different climatic conditions and soil types. The most widespread and important parasitic angiosperms belong to the genera Orobanche, Striga, and Cuscuta. The most important economical hosts belong to the Poaceae, Asteraceae, Solanaceae, Cucurbitaceae, and Fabaceae. Although some resistant cultivars have been identified in several crops, great gaps exist in our knowledge of the parasites and the genetic basis of the resistance, as well as the availability of in vitro screening techniques. Screening techniques are based on reactions of the host root or foliage. In vitro or greenhouse screening methods based on the reaction of root and/or foliar tissues are usually superior to field screenings and can be used with many species. To utilize them in plant breeding, it is necessary to demonstrate a strong correlation between in vitro and field data. The correlation should be calculated for every environment in which selection is practiced. Using biochemical analysis as a screening technique has had limited success. The reason seems to be the complex host-parasite interactions which lead to germination, rhizotropism, infection, and growth of the parasite. Germination results from chemicals produced by the host. Resistance is only available in a small group of crops. Resistance has been found in cultivated, primitive and wild forms, depending on the specific host-parasite system. An additional problem is the existence of pathotypes in the parasites. Inheritance of host resistance is usually polygenic and its transfer is slow and tedious. Molecular techniques have yet to be used to locate resistance to parasitic angiosperms. While intensifying the search for genes that control resistance to specific parasitic angiosperms, the best strategy to screen for resistance is to improve the already existing in vitro or greenhouse screening techniques.