miR172调控植物生长发育及逆境胁迫的研究进展

microRNA(miRNA)是一类内源性非编码小RNA,在植物整个生长发育过程中都起着重要作用,是基因表达的重要调控因子,而microRNA172(miR172)是众多miRNA家族中的重要的一员。为了更直观的认识miR172在植物中所发挥的作用,笔者归纳和总结了miR172在调控植物生长发育过程和响应逆境的研究进展,具体分析了miR172在植物营养生长阶段转变、开花、花器官发育、节间长度、植物商品器官发育以及逆境胁迫响应等诸多过程中发挥的作用。笔者认为miR172在植物中仍有很多未知的功能尚未发掘,因此未来深入挖掘和研究miR172在植物生长过程中更多的作用是一个重要的研究方向,在此基础上深入解析miR172在此过程中的功能、分子调控机制,为人为利用miR172调控植物生长发育奠定理论基础。     

兰科植物花器官发育MADS-box调控基因研究进展

兰科植物具有高度分化的花结构,是研究花器官发育调控机制的理想材料。目前,对兰花花器官发育调控基因研究已取得了一定进展。本文主要针对蝴蝶兰(Phalaenopsis aphrodite)、文心兰(Oncidium Gower Ramsey)、石斛(Dendrobium nobile)和中国兰(Cymbidium spp.)等兰花中已发现的花发育相关基因进行介绍。研究发现MADS-box基因在兰花的花器官形成过程中起重要作用,A、B、C、D和E类基因共同作用形成独特及多样的兰花结构。最后提出了兰科植物花器官发育现存问题及今后的展望。     

AGAMOUS在花发育中的核心功能研究进展

花是植物重要的生殖器官,受到多种花发育因子的调控。AGAMOUS(AG)在花发育的不同阶段有着不同的表达模式,对于植物的繁殖和发育有着重要的作用。AG与其他花发育基因、蛋白之间的相互作用决定了植物花器官的形态建成。近年来研究发现,AG基因对于花序分生组织向花分生组织的转化起到了关键的调控作用,特别是它与WUSCHEL(WUS)基因的反馈调节途径促进了植物生殖器官的发育。本综述总结了AG基因在植物花发育调控网络中的作用及生物学功能,展望了花发育未来的研究方向与发展趋势。     

SPL调控因子在植物生长调控的研究进展

SPL(SQUAMOSA promoter-binding protein-like)是植物特有的转录因子,它参与了植物叶、花、果实的发育、发育阶段转变、花青素的合成以及胁迫应答等调控过程。SPL转录因子家族成员均含有高度保守的SBP结构域,可以特异性结合所调控基因启动子的顺式作用元件,还可与其它调控蛋白相互作用,共同调控相关基因的表达。另外,SPL在转录后水平还受miRNA156/miRNA157的负调控。本研究从SPL调控因子在植物形态建成、次生代谢、生理胁迫中的表达调控研究进展方面进行综述。     

MicroRNA参与植物花发育调控的研究进展

摘 要：MicroRNA(miRNA)是一类20到24nt的非编码小RNA,通过与靶mRNA序列的互补配对产生特异性,抑制了mRNA的表达或使其降解,从而调控靶基因的表达。本文主要综述了三类调控开花时间的miRNA家族成员：miR172,miR159 / miR319和miR156。其中,miR156主要调控植物生长周期转变;miR172通过调控AP2类基因,控制开花时间和花器官的形成;miR159和miR319的过量表达均会引起一些花发育障碍,如花期延迟。此外,还介绍了其它一些与花发育相关的miRNA,并对miRNA在花形成和发育中的研究方向进行了展望。     

陆地棉MIKC~C基因家族的全基因组分析

【目的】MIKC~C是1类保守的转录因子家族,参与调控植物的开花时间和花器官发育。通过对MIKC~C家族进行全基因组学分析,为深入研究MIKC~C在棉花开花及花器官发育的分子调控机理提供基础。【方法】利用HMMER 3.0及pfam种子文件鉴定棉花全基因组MIKC~C基因,结合其表达量进行偏向表达及聚类分析。【结果】在陆地棉基因组中共鉴定发现100个MIKC~C基因,分为11个亚类。表达聚类分析显示,棉花MIKC~C基因的表达模式大致可分为4个不同的类群,说明这类基因在棉花进化中出现了功能分化。100个MIKC~C基因中,有12个基因具有miRNA靶位点。【结论】研究结果显示MIKC~C家族基因在棉花纤维中存在功能分化,而且可能受到miRNA的调控,这为进一步研究该家族基因的功能提供信息参考。     

杨树花发育相关基因及基因工程调控

杨树作为世界上重要的速生栽培树种和林木基因工程的模式树种,对其花发育分子机理的深入研究既是进行杨树开花调控的前提和基础,也为研究其它多年生木本植物花发育的研究提供借鉴.与其他开花植物相似,杨树的花发育也分为开花诱导、花的发端和花器官发育三个阶段,并且每个阶段都有多种基因的参与和调控.依据拟南芥等植物中花发育基因的信息,在杨树中也克隆了一大批与其花发育相关的基因,这些基因在表达方式、基因功能、调控等方面与其在拟南芥等植物中既有相似性,又具有杨树自身的特点.在杨树花发育相关基因的研究基础上,已经获得了提早开花及不育的转基因杨树.随着杨树花发育研究的不断深入以及实验技术的不断更新,杨树遗传改良必将发生历史性的变革.     

石榴YABBY基因家族的生物信息学分析

YABBY基因家族是种子植物特有的转录因子,该家族具有N-末端锌指结构域和C-末端螺旋-环-螺旋保守结构域;在植物的生长发育,特别是叶片的生长、果实的发育、花器官的形成和植物次生代谢物质的代谢中起重要作用。本研究从石榴基因组中鉴定到6个YABBY基因,并将其划分为5个亚族。不同器官和品种的表达分析表明:Pg YABBY基因家族在石榴的生长发育和生理过程中起重要作用。转录组分析表明:PgYAB2可能负调控石榴果皮和种子的发育。PgINO有可能负调控外种皮的发育。PgFILb基因有可能通过调控木质素或半纤维素等次生代谢物质的生物合成相关基因的表达进而调控石榴籽粒的硬度。本研究结果为石榴YABBY家族基因功能研究、探索YABBY调控石榴果实发育及品质形成提供参考,为石榴的分子育种提供科学依据。     

茄科蔬菜中miRNA响应低温胁迫研究进展

茄科蔬菜是典型的喜温性植物,由于本身无法躲避低温伤害,田间生产中易遭受低温胁迫。MicroRNA(miRNA)作为一种小分子RNA,是非蛋白质编码基因产物之一。低温胁迫下miRNA被激活,通过负调控靶基因、降解靶基因、抑制翻译等过程,调控相关基因表达,使植物从生理和分子水平上发生变化以响应低温胁迫。本研究主要从低温胁迫对茄科蔬菜的生理水平和转录水平的影响,miRNA差异表达、miRNA响应表达及miRNA与其靶基因作用模式两大方面进行阐述,以期揭示茄科作物中miRNA低温胁迫下相应的分子机制,为培育耐冷新品种提供坚实的理论依据和技术支撑。     

一个水稻长护颖突变体的遗传分析和基因定位

花器官发育异常突变体是研究植物花发育分子机理的重要材料。本研究在特种栽培稻品种"鸭血糯"中发现一个长护颖自然突变体,命名为Osleg(Oryza sativa long empty glumes)。组织细胞学分析表明,该突变体护颖的远轴表皮细胞凸凹不平,毛状体较多,许多瘤状体轴向平行排列,与外稃表皮细胞结构相似。遗传分析结果表明,该突变性状受一对隐性基因控制。将Osleg纯合体与籼稻品种9311杂交构建F2定位群体,利用已公布的水稻SSR标记和自行设计的STS标记对突变位点进行基因定位,最终将OsLEG定位在水稻7号染色体短臂上的LC15和LC25标记之间,物理距离约207kb,为进一步克隆OsLEG基因和研究禾本科植物花器官的分子调控机理提供了重要科学依据。     

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.     

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.     

Relation between wheat-rye crossability and seed set of common wheat after pollination with other species in the Hordeae

Summary Cultivars of common wheat (Triticum aestivum L. em. Thell.) of high wheat-rye (Secale cereale L.) crossability set more seed with pollen of other related species than did wheats of low wheat-rye crossability. This was found to be true for pollen parents from the genera Triticum, Aegilops, Secale, Agropyron and Elymus.     

Breeding apomictic bahiagrass (Paspalum notatum Flügge) with improved turf traits

The development of a turf‐type bahiagrass could have a remarkable impact on the billion‐dollar turf industry in the south‐eastern United States. The goals of this study were to (i) select bahiagrass genotypes with improved turf attributes and (ii) determine the reproductive mode and seed fertility of selected genotypes. The population included mutants, wild types, hybrids and standard cultivars evaluated at two locations for two years. Morphological variation was observed and clonal repeatability (H²) ranged from 0.27 to 0.90. Flowering was extremely reduced in some mutants, which also exhibited dark green colour, finer texture and reduced canopy height. Cytoembryological observations revealed that diploids reproduced sexually and tetraploids by obligate or facultative apomixis. Genotypes with superior seed fertility were identified, while others were comparable to the standard cultivars. While mutant plants exhibited great morphological variation, the random mutations did not affect their reproductive mode, validating the use of mutagenesis in apomictic species. The high H² indicated that selection for improved turf attributes could be successfully performed with the advantage of clonal seed propagation.     

Inheritance of fruit colour in a wild Russian red raspberry seedling

Summary A new gene, i, from a self-incompatible wild Russian Rubus idaeus seedling is described. The gene i interacts with the fruit colour gene T, Tii plants having apricot instead of red fruits, and spines, leaves and stems pigmented to varying degrees. A deficit of apricot-fruited seedlings in progenies segregating for i could be explained by linkage between i and the self-incompatibility S locus with a crossover value of approximately 26.7%.Segregations for spine colour in crosses and backcrosses of the Russian seedling with two green-spined (ttII) raspberries selected for their yellow fruit colour, showed that both the latter carried the spine colour intensifier gene P. This suggests that earlier authors were incorrect in attributing the apricot fruit colour developed by some tt plants to a pleiotropic effect of P.     

Flag Leaf Senescence, as Evaluated by Numerical Image Analysis, and its Relationship with Yield under Drought in Durum Wheat

Senescence was evaluated at different stages of the grain‐filling period in eight durum wheat varieties using numerical image analysis (NIA). The varieties were grown under early, severe drought conditions on the high plains of Sétif in Algeria. After flowering, three different irrigation treatments were applied. Treatment effect was small, while a genotypic effect was noted for most of the senescence parameters. Senescence correlated to biomass, while the maximal rate of senescence, V_smax, correlated to thousand‐kernel weight. The potential of the method of numerical image analysis for monitoring flag leaf senescence, detecting genotypic variability and selecting genotypes with delayed senescence is discussed.     

Mechanisms and diversity of resistance to sorghum shoot fly,Atherigona soccata

Sorghum shoot fly, Atherigona soccata, is one of the important pests of postrainy season sorghums. Of the 90 sorghum genotypes evaluated for resistance to this pest, RHRB 12, ICSV 713, 25026, 93046 and 25027, IS 33844‐5, Giddi Maldandi and RVRT 3 exhibited resistance in postrainy season, while ICSB 463, Phule Anuradha, RHRB 19, Parbhani Moti, ICSV 705, PS 35805, IS 5480, 5622, 17726, 18368 and 34722, RVRT 1, ICSR 93031 and Dagidi Solapur showed resistance in rainy season, suggesting season‐specific expression of resistance to A. soccata. ICSB 461, ICSB 463, Phule Yasodha, M 35‐1, ICSV 700, 711, 25010, 25019 and 93089, IS 18662, Phule Vasudha, IS 18551 and 33844‐5 and Barsizoot had fewer deadhearts than plants with eggs across seasons, suggesting antibiosis as one of the resistance mechanism. Five genotypes exhibited resistance with high grain yield across seasons. Correlation, path and stepwise regression analyses indicated that leaf glossiness, seedling vigour, trichome density, oviposition and leaf sheath pigmentation were associated with the expression of resistance/susceptibility to shoot fly, and these can be used as marker traits to select and develop shoot fly‐resistant sorghums.     

Cowpea (Vigna unguiculata): Genetics,genomics and breeding

Cowpea, Vigna unguiculata (L.), is an important grain legume grown in the tropics where it constitutes a valuable source of protein in the diets of millions of people. Some abiotic and biotic stresses adversely affect its productivity. A review of the genetics, genomics and breeding of cowpea is presented in this article. Cowpea breeding programmes have studied intensively qualitative and quantitative genetics of the crop to better enhance its improvement. A number of initiatives including Tropical Legumes projects have contributed to the development of cowpea genomic resources. Recent progress in the development of consensus genetic map containing 37,372 SNPs mapped to 3,280 bins will strengthen cowpea trait discovery pipeline. Several informative markers associated with quantitative trait loci (QTL) related to desirable attributes of cowpea were generated. Cowpea genetic improvement activities aim at the development of drought tolerant, phosphorus use efficient, bacterial blight and virus resistant lines through exploiting available genetic resources as well as deployment of modern breeding tools that will enhance genetic gain when grown by sub‐Saharan Africa farmers.     

Screening for resistance to take-all in wheat,triticale and wheat-triticale hybrid lines

Summary Fifteen triticale and wheat-triticale hybrid lines were evaluated for resistance to the take-all fungus Gaeumannomyces graminis var. tritici and compared with five wheat and two rye lines in inoculated field and pot trials. The triticale and wheat-triticale hybrid lines varied in rye chromosome number and degree of resistance expressed. One line, Venus with seven pairs of rye chromosomes consistently showed levels of resistance intermediate between wheat and rye. A trend was observed where increasing rye chromosome content led to greater resistance but exceptions showed that variation within triticales could not be ascribed to rye chromosome content alone.     

Reaction of tritordeum to Fusarium culmorum and Septoria nodorum

Summary Hordeum chilense is a wild barley extensively used in wide crosses in the Triticeae. It could be a valuable source of resistance to Fusarium culmorum and Septoria nodorum. Some H. chilense x Triticum spp. amphiploids, named tritordeums, were more resistant than the parental wheat line to these diseases, others were not. Average contents of ergosterol and deoxynivalenol (DON) suggested that resistance to colonization by Fusarium was the highest for Hordeum chilense, followed by tritordeum and wheat in decreasing order. In particular, the H. chilense genotypes H7 and H17 enhanced the wheat resistance to F. culmorum in its tritordeum offsprings. Resistance to S. nodorum in tritordeum was not associated with tall plant height. There is sufficient genetic variation for resistance to F. culmorum and S. nodorum among tritordeum to allow the breeding of lines combining short straw and resistance to both diseases.