油棕中果皮MYB转录因子家族的鉴定与表达分析

油棕(Elaeis guineensis Jacq.)是世界上最重要的油料作物之一,其中果皮含有的棕榈油极其丰富。MYB蛋白是一类广泛存在于真核生物中的转录因子,在植物的生长发育中发挥重要调控作用。本研究基于油棕中果皮转录组的测序结果为基础,利用生物信息学对油棕MYB基因家族进行全面鉴定,并对这些基因的结构、保守域和果实发育不同时期动态表达进行研究,解析油棕MYB转录因子在油棕发育过程中的生物学功能。结果发现,本研究中的38个油棕MYB转录因子,包含26个R2R3-MYB型和8个MYB-related型,以及2个3R-MYB型,不包含4R-MYB类型;MYB蛋白编码约200～700个氨基酸,等电点在4.5～9.5之间;亚细胞定位预测结果显示,所有MYB基因均定位于细胞核中;油棕MYB蛋白具有相似的保守基序组成,38个基因主要分布在13条染色体上,含有1到10个外显子数目;油棕MYB转录因子与多个物种的MYB转录因子具有序列同源性和进化亲缘性;表达模式分析发现,MYB家族基因存在差异表达,且具有几种不同的表达趋势。该研究结果为今后油棕MYB转录因子的脂类代谢途径研究以及功能和调控机制提供重要的研究基础。     

银杏FLS基因启动子克隆及序列分析

黄酮醇合成酶基因（FLS）是黄酮类化合物合成通路中的重要基因,直接决定着银杏黄酮类化合物的积累量。为了探索FLS基因在转录水平上的表达调控机制,本文在克隆银杏FLS基因启动子序列的基础上,利用生物信息学方法,分析了该基因的启动子结构。结果表明,FLS基因启动子中包含了3个MYB转录因子结合位点和9个光信号应答位点,为确立银杏FLS基因与CHI基因间的共调控关系及揭示FLS基因应答光信号的转录调控机制提供了分子基础。     

枸杞LbMYB12基因的克隆及表达特性分析

类黄酮是植物中一类重要的次生代谢产物,枸杞黄酮以其强抗氧化作用以及对心脑血管疾病的抑制和改善功能而广为人知。MYB转录因子参与类黄酮代谢过程的调控。本研究采用RACE技术克隆了枸杞LbMYB12基因全长cDNA序列。生物信息学分析表明,LbMYB12基因的完整开放阅读框(ORF)长930 bp,具有MYB蛋白家族保守结构域,蛋白质相对分子量为35.56 kD,等电点为5.05,其二级结构主要为α-螺旋。荧光定量PCR分析表明,LbMYB12基因在枸杞整个植株中均有表达。其中,在根中的表达量最低,在青果中的表达量最高。LbMYB12基因在果实不同发育时期的表达分析表明,开花后早期表达量显著高于成熟期果实。本研究为进一步探讨枸杞LbMYB12转录因子在类黄酮代谢中的作用提供了研究基础。     

在低氮肥胁迫下马铃薯MYB转录因子的特征分析

MYB转录因子对调控植物生长发育和抗逆等多种生理反应发挥着重要作用。为探究MYB转录因子对马铃薯低氮肥胁迫的调控作用,对马铃薯苗期进行了低氮肥胁迫处理后,分别取根和叶片进行转录组测序,进而对有差异表达的MYB转录因子家族基因进行生物信息学分析。结果表明,36个MYB转录因子基因在根和叶片中显著性差异表达,且对应启动子区域的激素相关调控元件也呈现出差异的组成与分布;其中6个候选的响应低氮肥胁迫MYB转录因子与拟南芥中主要参与抗逆的MYB转录因子存在较近亲缘关系。基于对马铃薯MYB转录因子的研究,推测这6个表达差异的MYB类转录因子基因可作为马铃薯响应低氮肥胁迫的重要候选基因,可为后续研究氮高效马铃薯新品种提供理论依据。     

基于转录组的番木瓜MYB基因家族的生物信息学分析

MYB基因家族作为高等植物最大的一类转录因子家族,调节植物的生长发育及代谢。到目前为止,针对番木瓜MYB转录因子家族的研究仍相对较少。本研究基于番木瓜转录组测序数据,筛选出34个在番木瓜果实成熟过程中表达显著差异的MYB类转录因子基因,并对其蛋白序列进行理化性质、亚细胞定位和系统进化等生物信息学分析。本研究依据MYB保守域的个数将34个番木瓜MYB类转录因子分为1R-MYB和R2R3-MYB两类。上述MYB基因编码蛋白的氨基酸数目在141～1 709个之间,其分子量分布在16 312.94～186 299.92 Da范围内,皆为不稳定的亲水性蛋白。上述34个蛋白均不含信号肽,绝大部分以α-螺旋与无规卷曲为主要的二级结构元件。亚细胞定位分析表明,番木瓜MYB蛋白主要分布在细胞核。进化树分析显示番木瓜MYB蛋白与拟南芥MYB蛋白可被分为三个亚类,即亚类聚类Ⅰ、Ⅱ和Ⅲ,推测聚在同一个亚类上的转录因子可能具有相似的功能。研究结果为进一步探究MYB家族的基因功能提供了基础数据,也为其他物种MYB转录因子的研究分析提供一定的帮助。     

黄瓜CsRAX2的克隆与表达分析及原核表达蛋白诱导

作为最大的转录因子家族,MYB转录因子广泛参与植物的生长发育以及对胁迫的响应与耐受。CsRAX2是黄瓜MYB转录因子家族成员之一,本研究通过同源克隆法克隆了CsRAX2全长,分析了该转录因子基因的生物信息和表达特征,在原核表达系统中诱导并纯化该蛋白。结果表明,CsRAX2全长939 bp,编码321个氨基酸,定位在3号染色体。CsRAX2蛋白定位在细胞核,与其他物种MYB的进化关系很近,是一个典型的R2R3-MYB转录因子。CsRAX2表达具有组织特异性,且低温处理显著诱导采后黄瓜CsRAX2表达,表明其可能在采后黄瓜低温反应调控中发挥作用。启动子元件分析显示,该基因启动子中含有多个环境和激素响应元件,表明非生物胁迫可能通过激素信号调控CsRAX2表达。原核表达研究表明,培养温度影响原核表达蛋白的诱导效果,降低细菌培养温度能提高上清液中融合表达蛋白产量。本研究结果为进一步研究黄瓜CsRAX2基因的生物学功能及黄瓜耐冷性机理提供了帮助。     

观赏羽衣甘蓝BoMYB114基因编码区的克隆及序列分析

花青素是羽衣甘蓝叶片呈紫色、红色及粉色的重要色素,R2R3-MYB类蛋白被认为是调控植物花青素生物合成的转录因子。本研究以羽衣甘蓝叶片为试材,采用同源克隆的方法克隆BoMYB114转录因子基因的编码区序列,并对其进行生物信息学分析。结果表明:BoMYB114基因编码区长度为753 bp,其包含1个完整的开放阅读框ORF,可编码250个氨基酸,预测蛋白的分子量为28.5 kD,等电点(pI)为9.08。BoMYB114蛋白不存在信号肽,很可能定位在细胞核中。BoMYB114蛋白含有2个MYB保守结构域,二级结构以无规则卷曲、α-螺旋、延伸链和β-转角为主。进化树分析表明,羽衣甘蓝的BoMYB114蛋白与甘蓝型油菜MYB114蛋白序列的一致性最高。羽衣甘蓝BoMYB114基因的克隆与序列特征分析对于进一步研究该基因结构和功能及植物花青素合成代谢途径具有重要意义。     

调控植物类黄酮生物合成的MYB转录因子研究进展

类黄酮是一类多酚类次生代谢产物,在植物中广泛存在,具有调节机体免疫力、抗氧化、抗衰老以及抵抗病毒等医疗保健功效。在类黄酮生物合成过程中,MYB转录因子扮演者重要角色,可以调控与类黄酮合成相关的酶基因的表达,从而有效地调控类黄酮物质的生物合成。目前已在很多植物中分离克隆得到了很多调控类黄酮生物合成的MYB转录因子,并对它们的结构功能及表达方式和作用模式进行了深入研究。利用转基因技术将从特定植物中分离得到的MYB转录因子用于植物遗传改良,可有效提高转基因植物中黄酮类物质的含量。因此,MYB转录因子的研究对从分子水平上研究和调节类黄酮的合成具有重要的意义;转录因子的应用是类黄酮生物合成基因工程中的一个新方向。     

玉米淀粉调控的研究进展

为了明确淀粉合成途径中的关键酶的功能和调控机制,本文综述了玉米淀粉的结构、淀粉合成途径以及调控淀粉合成转录因子（DOF、NAC、MYB、bZIP、MADS-BOX和AP2/EREB等家族）的表达和功能机制。研究表明大部分转录因子能在玉米胚乳中表达,少数也能在叶片中表达;这些转录因子可以通过与淀粉合成酶编码基因和关键调控基因的启动子结合从而影响其表达来调控淀粉的合成。此外,蔗糖/ABA、蔗糖/IAA也可以和转录因子协同调控淀粉的合成。本文能够加深对玉米淀粉合成调控的理解,也为玉米品质改良提供重要的理论依据。     

牛樟芝MYB转录因子的全基因组鉴定与分析

MYB转录因子在真菌的生长发育和胁迫响应中发挥多种作用。为了解牛樟芝MYB的功能,本研究利用本地BLAST对牛樟芝基因组进行比对分析,获得了9个牛樟芝MYB基因序列,并对牛樟芝MYB转录因子进行功能预测分析,利用转录组测序分析MYB基因在不同段木培养条件下子实体和菌丝体中的表达情况。蛋白理化性质分析发现,9个牛樟芝MYB转录因子多为不稳定蛋白,理论等电点介于4.92～8.51;亚细胞定位预测结果显示有1个转录因子(ACMYB1)定位在细胞质中,推测其可能参与细胞质基因的转录调控;有8个定位在细胞核中,占总蛋白的88.9%。二级结构预测发现以无规则卷曲和α-螺旋为主要结构,β-转角为次要结构。将9个牛樟芝MYB转录因子与5个已知功能的MYB蛋白共同构建系统进化树,14个MYB转录因子分为Ⅰ、Ⅱ两个分支,其中ACMYB1、ACMYB5与冬虫夏草中参与菌丝生长的MYB-6聚为一支,ACMYB9与冬虫夏草中参与子实体生长的MYB-3聚为一支,ACMYB6与顶头孢霉AcMYBA聚为一支。分析牛樟芝MYB转录因子在不同段木菌丝和子实体中的相对表达量,发现ACMYB1、ACMYB5、ACMYB6均在...     

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.