茄科植物转录因子MYB基因家族的研究进展

植物转录因子MYB是能与真核基因启动子区域特异性相互作用的DNA结合蛋白,在植物中普遍存在,同时也是植物中最大的转录因子家族之一,MYB转录因子通过彼此之间或与其他相关蛋白之间的相互作用,能够调控基因的表达。迄今为止的研究表明,其成员广泛参与了茄科(Solanaceae)植物的生长发育、次级代谢、逆境胁迫应答和激素信号转导等进程。本研究主要对MYB转录因子的结构特点、生物学特性以及调控机制等方面归纳总结前人的研究成果,详细阐述国内外相关研究进展,以期为茄科植物分子育种方面的研究提供新的思路与方法。     

植物转录因子MYB基因家族的研究进展

植物转录因子MYB(v-myb avian myeloblastosis viral oncogene homolog)是近年来发现的一类与调控植物生长发育、生理代谢、细胞的形态和模式建成等生理过程有关的一类转录因子,在植物中普遍存在,同时也是植物中最大的转录家族之一,MYB转录因子在植物的代谢和调控中发挥重要作用。大多数MYB蛋白在N端含有一段氨基酸残基组成的Myb结构域,根据这个高度保守的结构域的结构特征可将MYB转录因子分为四类:1R-MYB/MYB-related;R2R3-MYB;3R-MYB;4R-MYB(4个R1/R2的重复)。MYB转录因子具有多种生物学功能,广泛参与植物根、茎、叶、花的生长发育,与此同时,MYB基因家族对干旱、盐渍、冷害等非生物胁迫过程也有响应,此外MYB转录因子还与某些经济作物的品质好坏密切相关。本综述主要对MYB转录因子的结构特点、生物学特性、调控机理等方面归纳总结前人的研究成果,详细阐述国内外相关研究进展,以期为后续研究做相关参考。     

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。     

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。     

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。     

高山杜鹃转录组测序及MYB转录因子家族分析

MYB转录因子是植物中最大的一类转录因子家族,参与调控植物的生长发育、次生代谢、逆境胁迫等生物学过程.目前,关于高山杜鹃MYB转录因子的研究尚未见报道.本研究利用SMRT高通量测序技术对高山杜鹃品种'富丽金陵'进行转录组测序,得到了15.37 Gb数据,通过去冗余获得75002条转录本序列.其中,71155、33653、30359条转录本分别在NR、GO、COG数据库中具有匹配信息.基于高山杜鹃转录组数据,鉴定了64个转录因子家族,其中MYB基因有220个.根据结构特性将MYB基因分为4类:1R-MYB、R2R3-MYB、R1R2R3-MYB和4R-MYB,其氨基酸序列包含20种保守元件.进化树分析结果显示,高山杜鹃MYB基因分为28个亚组.研究采用单分子实时测序技术(single molecule real time,SMRT)对高山杜鹃品种'富丽金陵'转录组进行测序,将获得的转录本序列进行功能注释和分类,对获得的220个MYB基因进行生物信息学进行分析,相关结果具有一定参考意义.     

禾谷镰刀菌MYB转录因子生物信息学分析

本研究利用生物信息学方法对真菌转录因子数据库收录的17条禾谷镰刀菌MYB转录因子序列进行了分析。基因序列和蛋白理化性质分析发现,禾谷镰刀菌17个MYB转录因子在核酸长度、蛋白大小、理论等电点、原子总数以及不稳定系数方面均存在差异;基序分析和蛋白二级、三级结构预测发现,这些转录因子包含2条特征基序,蛋白空间结构多样且均包含MYB转录因子特征结构(螺旋-转角-螺旋(HTH));系统进化树分析表明,17个禾谷镰刀菌MYB转录因子与12个已报道的其他物种MYB转录因子进化出两个大的分支,其中Fg MYB03、Fg MYB04、Fg MYB05、Fg MYB06、Fg MYB10、Fg MYB12和Fg MYB13与已知功能的动物、植物和真菌MYB转录因子c-MYB、ATMYB2、MoMyb1、FlbD和Pol5等具有较近的亲缘关系,推测它们具有类似的生物学功能。本研究结果为进一步研究禾谷镰刀菌MYB转录因子的生物学功能以及其他真菌MYB转录因子的家族特征提供了依据。     

转录因子和启动子互作分析技术及其在植物应答逆境胁迫中的研究进展

转录因子是一类调节基因表达的重要调控蛋白,转录因子和与其结合的启动子中的相关顺式作用元件,在基因表达方面起着分子开关的作用,因此探究转录因子与启动子的相互作用尤为重要。为了研究在植物遭受逆境胁迫时,转录因子对下游靶基因的调控机制,本文综述了参与逆境胁迫的主要转录因子家族、转录因子的转录激活活性鉴定、转录因子和启动子互作分析技术及其在植物应答逆境胁迫中的应用,为全面、深入研究植物应答逆境胁迫时的基因表达调控机制提供参考。     

基于转录组数据的绢毛委陵菜MYB转录因子家族分析

利用生物信息学方法，从绢毛委陵菜转录组数据中筛选出63个MYB转录因子，分析了它们的转录因子家族序列特征、理化性质、保守结构域、亚细胞定位和进化关系。结果表明，筛选出的63个绢毛委陵菜转录因子，其中1R-MYB类22个、R2R3-MYB类37个、3R-MYB类3个、4R-MYB类1个。结构域分析表明其具有典型的W型R2R3保守基序；绢毛委陵菜的所有MYB基因都是亲水性不稳定蛋白；而亚细胞定位预测都位于细胞核内；系统进化分析将绢毛委陵菜R2R3-MYB类蛋白分为22个亚家族，其中参与调控重金属镉相关的拟南芥同源基因主要属于S20亚族。研究结果为深入探究绢毛委陵菜MYB基因在调控重金属镉过程中发挥的功能提供基础资料。     

基于RNA-Seq的彩色马铃薯MYB转录因子家族分析

植物MYB转录因子是功能多样、数量众多的转录因子之一,对植物的生长发育和代谢调控起着极其重要的作用.本研究基于彩色马铃薯块茎转录组测序数据,对彩色马铃薯发育过程中MYB转录因子基因进行筛选,并对其保守结构域、亚细胞定位进行分析;同时利用TMEV软件对其中R2R3-MYB转录因子的差异表达进行分析,并对差异显著的R2R3-MYB转录因子进行功能预测.结果 表明,基于转录组测序数据,筛选得到143个彩色马铃薯MYB类转录因子基因,根据结构特征分为4大类:1R-MYB、R2R3-MYB、3R-MYB和4R-MYB;亚细胞定位结果显示,138个MYB转录因子定位于细胞核,4个定位于细胞膜,1个定位细胞质;保守域分析显示,R2R3-MYB类转录因子的保守基序为R2、R3;彩色马铃薯R2R3-MYB转录因子基因在不同时期差异表达,其中上调表达10个、下调表达5个;根据GO富集性分析,共注释到6个和花青素相关的R2R3-MYB转录因子,本研究为下一步彩色马铃薯花青素合成相关MYB基因生物学功能和代谢调控机制的研究提供参考.     

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.     

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.     

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.     

A note on the origin of Kalanchoë x vadensis Boom & Zeilinga (Crassulaceae)

Summary K x vadensis is a hybrid of K. blossfeldiana and K. marmorata obtained after doubling the number of chromosomes.     

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...     

Avoidance of leaf rust fungi in wild relatives of cultivated cereals

Summary Avoidance of rust fungi that was based on poor appressorium induction was previously found in Hordeum chilense. In the present study 95 accessions of Triticeae were screened for avoidance of Puccinia hordei. The percentage of appressorium formation per germinated spore ranged from 6 to 90%. On none of the 41 accessions of Aegilops, Agropyron, Elymus, Secale, Thinopyrum or Triticum studied was the rate of appressorium formation lower than 25%. Lower rates of appressorium formation were, however, found on accessions of wild barley species Hordeum brachyantherum, H. marinum, H. parodii and H. secalinum. Its implications in cereal breeding are discussed.     

Variation in forage grasses as hosts of the root-knot nematode Meloidogyne naasi (Franklin) and selection for resistance in ryegrass

Summary Reactions of 13 grasses to Meloidogyne naasi varied with species; ryegrasses, fescues and their hybrids were generally susceptible and cocksfoot and timothy resistant. Marked variation in host resistance levels occurred between genotypes within cultivars.Selection of single plants, followed by tests on replicate tillers, identified resistant and susceptible genotypes in both Italian and perennial ryegrass cultivars. Resistant plants had few nematode-induced galls and fewer females and eggs than susceptibles. There was more or less continuous variation, with many genotypes intermediate between extremes of resistance and susceptibility. Selected resistant and susceptible genotypes are of use in assessing variation in nematode populations and as controls for breeding and selection programmes.     

Current and future strategies in breeding lentil for resistance to biotic and abiotic stresses

Lentil production is limited by lack of moisture and unfavorable temperatures throughout its distribution. Waterlogging and salinity are only locally important. Progress has been made in breeding for tolerance to drought through selection for an appropriate phenology and increased water use efficiency and in breeding for winter hardiness through selection for cold tolerance.The diseases rust, vascular wilt, and Ascochyta blight, caused by Uromyces viciae-fabae, Fusarium oxysporum f. sp. lentis, and Ascochyta fabae f. sp. lentis, respectively, are the key fungal pathogens of lentil. Cultivars with resistance to rust and Ascochyta blight have been released in several countries and resistant sources to vascular wilt are being exploited. Sources of resistance to several other fungal and viral diseases of regional importance are known. In contrast, although the pea leaf weevil (Sitona spp.) and the parasitic weed broomrape (Orobanche spp.), and to a lesser extent the cyst nematode (Heterodera ciceri), are significant yield reducers of lentil, no sources of resistance to these biotic stresses have been found. Directions for future research in lentil on both biotic and abiotic stresses are discussed.     

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.     

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...