草莓分子标记技术发展与应用

栽培草莓(Fragaria×ananassa)为八倍体多年生草本植物,具有复杂的遗传背景,多数农艺和品质性状均为多基因控制,为草莓的遗传育种工作带来了挑战。DNA分子标记直观反映基因组的差异和变化,对于遗传高度杂合、生产周期长的多年生果树来说,能够有效提高育种效率。近年来,分子标记技术在果树辅助育种、基因定位、遗传图谱构建、QTL定位、品种鉴定和基因组研究等方面应用广泛,有力地推动了果树分子育种的发展。本文综述了分子标记技术在草莓生产育种中的研究应用现状,以期为后续的研究提供参考,推动草莓的生产和育种。     

草莓组织培养研究综述

从草莓不同组织器官组培快繁、外源激素在组培中的应用、不同草莓品种的组培快繁、草莓组培快繁培养基表面消毒时间等方面,对近年来草莓组培快繁技术的研究进展进行了综述,并着重对脱毒率、成活率及褐化问题进行了分析。     

大豆光能高效利用的分子调控机制研究进展

光合作用是影响作物产量的重要因素,长期以来国内外科学家通过高光效育种对大豆产量的提高起到了重大的促进作用。近年来,随着植物光合分子生物学研究和基因工程技术的发展,有关大豆光合作用分子机制和光能利用效率分子调控的研究取得了很多进展。本文总结了大豆光合作用相关的基因,综述了调控光能利用效率相关因子的研究进展,以期为大豆高光效分子设计育种提供理论指导。     

~(60)Co-γ射线辐射草莓红颊诱变选育新品系的研究

为丰富草莓育种方法,以红颊草莓为试验材料,进行辐射诱变并结合组织培养复合育种技术的探索。采用不同辐照剂量~(60)Co-γ射线处理红颊草莓叶片愈伤组织,定向筛选获得优质诱变系2010-30。对红颊和诱变系2010-30的农艺性状、营养品质、柱头可授性、花药活力等指标进行测定,比较分析红颊和诱变系2010-30各指标的差异性。结果表明,~(60)Co-γ射线辐照的最佳剂量为20 Gy;诱变系2010-30的Vc含量为0.663 mg·g-1、可溶性固形物含量为11.65%、硬度为571.71 g,均高于红颊;诱变系2010-30的柱头可授性强于红颊,且花粉败育率明显低于红颊。通过~(60)Co-γ射线辐射获得的诱变系2010-30可作为草莓育种的新种质资源,并可作为新品系在生产中推广应用。本研究结果为增加草莓遗传变异、创造新的种质材料、选育新品种(系)以及辐射诱变结合组织培养复合育种技术的研究提供了技术参考和理论依据。     

我国芦笋育种研究进展及展望

我国芦笋种植面积、产量和出口量居世界首位,但种子主要依赖进口。近年来,我国在芦笋育种方法和技术上取得了快速的发展。本文对我国在芦笋无性系杂交育种、全雄育种、多倍体育种、分子标记辅助育种等育种关键技术,及芦笋杂交技术、组织培养技术、种子生产技术等方面的研究进行了综述,同时对今后的芦笋育种技术及发展方向提出了建议。     

根癌农杆菌介导转褪黑素基因草莓的获得

为建立根癌农杆菌介导的草莓褪黑素基因高效遗传转化体系,以草莓品种“早红”叶片和叶柄为外植体,优化了影响根癌农杆菌遗传转化的因素,包括农杆菌菌液浓度、侵染时间、共培养时间和预培养时间等,建立了适宜草莓“早红”的农杆菌遗传转化体系。结果表明,“早红”草莓适宜的转化条件是：外植体的最适预培养时间为2～3 d,农杆菌侵染的最佳菌液浓度为OD600 0.3～0.5,最适侵染时间为15 min,最适共培养时间为3 d。在此基础上,通过根癌农杆菌介导法将褪黑素合成关键酶N -乙酰转移酶（AANAT）和羟吲哚-氧甲基转移酶（HIOMT）基因AANAT和HIOMT转入草莓基因组,并对获得的抗性植株进行PCR和PCR-Southern blot检测分析,结果表明外源基因已经整合进草莓基因组中。RT-PCR分析证明外源基因已经在转录水平表达。     

茶树精油熏蒸处理保鲜草莓的工艺优化

为了获得茶树精油熏蒸处理进行草莓防腐保鲜的较佳工艺条件,采用单因素试验方法研究不同熏蒸体积分数、温度和时间对人工接种灰葡萄孢霉的草莓果实腐烂发生的影响。通过Box-Behnken设计及响应面分析获得熏蒸防腐保鲜的最佳工艺条件为:茶树精油熏蒸体积分数0.66mL/L、熏蒸温度33.3℃、熏蒸时间3.1h。按此优化条件进行验证发现接种草莓果实的腐烂指数为7.5%,实测值与模型预测值的相对误差在4.1%;将此优化条件应用于未接种的新鲜草莓果实,结果发现该处理能显著抑制果实的自然病害发生,还能减缓草莓果实失重率的上升和果实硬度、可溶性固形物、可滴定酸和花青素含量的下降。研究结果为茶树精油在草莓保鲜上的商业化应用提供参考。     

化学诱变提高植物抗逆性的研究进展

化学诱变是农业上一种传统的育种技术,在植物抗逆育种方面受到育种家的青睐,用于改善植物的抗寒、抗旱、耐盐碱性等育种方面的研究。植物组织培养技术是实现细胞或个体快速繁殖的有效途径。以上两种技术的结合,可有效提高突变的频率,人为扩大植物遗传变异范围。近年来,化学诱变与生物技术结合在植物抗逆诱变育种方面展现出了积极的发展前景,对于植物新品种选育具有重要的实践意义。本研究综述了化学诱变的特点、常用化学诱变剂[主要是甲基磺酸乙酯(EMS)和叠氮化钠(NaN₃)]的诱变机制、使用方法、诱变效果以及影响化学诱变的因素等,并介绍了化学诱变在植物抗逆育种领域中的新近研究进展。     

草莓干冰喷射速冻过程的数值模拟与优化

为了有效提高速冻后草莓的品质,该研究提出干冰喷射速冻草莓的方法,设计了干冰喷射速冻草莓的速冻间和干冰喷射装置,利用Comsol软件对速冻间内干冰喷射草莓速冻过程的温度场、速度场和压力场进行模拟,研究了不同干冰喷入速度(0.10、0.15、0.20、0.25、0.30、0.40、0.50m/s),喷入口半径(18、20、23、25、30mm),以及干冰喷入速度为0.20、0.30 m/s时模型内干冰体积分数变化对草莓速冻效果的影响。结果表明:随着干冰入口半径的增加和干冰喷入速度的提高,草莓会更快的冻结。在入口半径为25 mm,流速为0.30 m/s情况下,可以高效实现草莓速冻。对干冰速冻草莓降温性能进行分析,并与现有液氮喷淋速冻草莓降温性能进行比较,结果表明:干冰速冻草莓通过最大冰晶带和草莓完全冻结的时间分别减少63.9%和41.7%,草莓能最大限度地保持原有的新鲜状态和营养成分。对优化的结果进行试验验证,草莓表面温度和中心温度达到标准时误差分别为3.70%和6.03%,草莓干冰速冻前后的品质指标均优于草莓速冻标准。研究结果为进一步开发节能环保的干冰速冻草莓装置提供参考。     

EMS诱发草莓不同组培材料的耐盐性变异

以全明星草莓花药诱导的愈伤组织以及组培苗叶片为试验材料,用化学诱变剂甲基磺酸乙酯(EMS)进行诱变处理。结果表明,愈伤组织诱变处理的适宜浓度与时间组合为0.1%+1.5h和0.2%+1.0h,而(0.2%~0.4%)+(1.0~2.0h)可作为离体叶片诱变处理的适宜浓度和时间范围。与离体叶片诱变相比,草莓花药的愈伤组织对诱变剂EMS更为敏感。通过对再生植株的耐盐性进行比较发现,愈伤组织诱变筛选植株的盐害率和盐害指数低于离体叶片诱变筛选植株,说明愈伤组织较组培苗叶片更适于作为草莓耐盐诱变育种的起始材料。     

Development of new sources of tetraploid <Emphasis Type="Italic">Arachis</Emphasis> to broaden the genetic base of cultivated groundnut (<Emphasis Type="Italic">Arachis hypogaea</Emphasis> L.)

Groundnut, an important crop of many countries of the world, is susceptible to a range of diseases and pests. High levels of resistances are not available in the cultivated gene pool as the crop is said to have a narrow genetic base. Narrow genetic base is attributed to the evolution of the crop which took place by the combination of A and B genome species, and later doubling their chromosome number, giving rise to tetraploid cultivated groundnut. Direct utilization of cross-compatible wild relatives, which are diploids, to broaden the genetic base and introduction of useful traits, is not a straight-forward process due to ploidy differences between the cultivated species and wild relatives. Hence amphiploids and autotetraploids were created by not only combining the putative genomes, but many other A and B genome species, thus producing a highly variable population of tetraploid groundnuts also called new sources of Arachis hypogaea. This study describes the development and characterization of newly generated tetraploid groundnuts and the level of molecular diversity as assessed by DArT markers.     

Wild crop relative populations hot-spots of diversity are hot-spots of introgression in the case of pearl millet

Wild crop relatives are unique genetic resources for crop adaptation. Increasing pressure from agriculture threatens these populations both by reducing their habitats and by creating opportunities for wild-cultivated hybridization. In this study, we assessed the diversity of 38 wild pearl millet populations covering the whole known distribution of the species in Africa, which extends from Senegal to Sudan. Using genetic analyses of 10 cultivated varieties as control, we demonstrate the high diversity harbored by these wild populations. Diversity patterns suggest a diversity hot-spot in the southern part of the wild population’s range. However, this high wild genetic diversity could partly be explained by introgression from cultivated varieties. Such introgression is widespread in the Sahel. We validate the impact of cultivated introgression on the diversity of the wild population using a genetic introgression model. The introgression distorts the real assessment of the diversity of the wild population, and the burden of this gene flow compromises the long term survival of the wild populations’ original genome. Our study also questions the long term survival of the crop’s wild relatives.     

Close Genetic Proximity Between Cultivated and Wild Bactris gasipaes Kunth Revealed by Microsatellite Markers in Western Ecuador

Bactris gasipaes Kunth (peach palm or Pejibaye) is the only domesticated palm of the Neotropics. The genetic relationships between the crop and its wild relatives are still unclear. We undertook field and laboratory work in order to describe differentiation and relationships between the wild and cultivated populations of the species in Western Ecuador, and their possible interactions. A volumetric study was undertaken on the fruits of both populations, as well as a population genetic analysis in order to clarify these relationships. Fruits from cultivated plants collected in the region of sympatry of wild and cultivated plants in North-West Ecuador showed intermediate volumes between those of reference samples for the wild and cultivated plants in allopatry. Using 8 microsatellite loci, we assessed 83 wild and cultivated individuals from Western Ecuador and cultivated plants from Amazonia and Central America as a reference for the cultivated form. We detected high polymorphism in the wild and cultivated samples and low, but significant level of genetic differentiation between wild and cultivated populations. The cultivated population in North-Western Ecuador showed close genetic proximity with the sympatric wild population, consistent with the volumetric study. These results have implications for hypotheses on evolution of this crop and for strategies of genetic conservation of the wild forms.     

Plant genetic resources of Lemnos (Greece), an isolated island in the Northern Aegean Sea, with emphasis on landraces

Lemnos Island is located in the Northern Aegean Sea and presents a rich biodiversity in plant genetic resources including wild species and crop landraces. Landraces have been cultivated under traditional agricultural systems and many have survived genetic erosion. They are mainly conserved in home gardens or in small fields, usually by elderly people, and are limited to local consumption. Two collecting expeditions were organized in Lemnos, a minor one in 2009 and a larger one in 2010. The results of the two current expeditions are discussed and compared with previous expeditions in the island. An overview is given on the crops cultivated, the landraces collected and those considered as lost, alongside with some information about their traditional uses. Finally, the importance of landraces in modern agriculture and preservation policies in Lemnos are discussed.     

The diversity and sustainable development of crop genetic resources in the Lancang River Valley

This paper reviews the status of crop genetic resources in Yunnan province of China from 1978 to 1999. Results are presented of same research in the field of the diversity of cultivated and wild crop. Yunnan is one of the centre of origin or genetic diversity of more than 200 cultivated and wild crops. There are over 500 cultivated plants which account for over 80% of the total in China and more than 650 species of wild crops. In addition, there are more than 440 species of main wild flowers. According to our recently researches there are abundant species, subspecies and varieties of crop genetic resources in Yunnan Province. The Lancang River Valley is the richest genetic diversity centre of rice, maize, wheat, barley, buckwheat, legumes, ramie, sugarcane, vegetable, tea, actinidia and so on. For example, there are 59 varieties (including all varieties of Oryza sativa L. in China) in 5933 accession of Yunnan indigenous rice. The Lancang River Valley is one of the centre for genetic diversity of rice resources and a rich region for elite and rare rice resources of Yunnan, too. In order to protect the highly endangered crop genetic resources in the Lancang River Valley, it is necessary and very important to set up a collection, conservation, utilization and research system, enhancing their protection and utilization, in situ- and ex situ-conservation, farm management and sustainable production.     

Temporal changes of soil physical and hydraulic properties in strawberry fields

Even over short time intervals, soil properties are subject to variation, especially in managed soils. The objective of this study was to assess the temporal changes of soil physical and hydraulic properties in strawberry fields cultivated under surface drip fertigation in Turuçu, Brazil. Intact core samples were collected from the near surface soil layer of seedbeds to determine the total porosity (TP), macroporosity (MA), matrix porosity, bulk density (BD), available water capacity (AWC), field capacity, wilting point and Dexter’s S index. Aggregate samples were collected from the arable layer to determine the aggregate size distribution and aggregate mean weight diameter. All samples were collected from 15 strawberry fields and at four different times during the 2007–2008 strawberry growing cycle. Although soil pore‐solid relations are expected to adjust soon after seedbed construction, their variation was only evident after >13 weeks. Even though values of TP and MA decreased with time, and those of BD increased near the end of the growing cycle, all the soils maintained their capacity to support root activity as indicated by critical values of Dexter’s index (S > 0.03). The amount of relatively large aggregates (9.51–2.00 mm) and AWC increased towards the end of the strawberry cultivation cycle. With changes in soil structure improving soil physical quality, strawberry development benefitted. We showed that if farmers gradually increase the amount of water through fertigation to a maximum value occurring at the end of crop cycle instead of applying water at a constant rate, water and energy use efficiency in agriculture would improve.     

Oman at the cross-roads of inter-regional exchange of cultivated plants

During the past years the Sultanate of Oman which is located at the south-eastern tip of the Arabian peninsula has been studied for its cultivated plant genetic resources. Data from this study, that commenced in 2002 and information from the literature have been combined to document the millenia-old cultivation history of many agri- and horticultural crop plants in this country at the cross-roads of inter-regional exchange. The resulting checklist comprises 194 species from 133 genera and 53 families and 11 geoelements of 136 selected species. Notable inputs came from South and Southeast Asia with 21.3%, from the Near East and East Mediterranean with 20.6%, and from Central and South America with 15.4%. Most elements are allochthonous while real autochthonous elements such as Boswellia sacra Flueck. and Prunus arabica (Oliv.) Meikle are rare. A remarkable infraspecific variation in several crop species and evidence of introgession were found indicating an evolutionary power of Oman that is similar to that of South Italy.     

Peat amendment and production of different crop plants affect earthworm populations in field soil

A field experiment was conducted to study the effects of peat amendment and crop production system on earthworms. The experiment was established on a field previously cultivated with oats and with silt as the main soil type. Perennial crops strawberry, timothy and caraway, and annual crops rye, turnip rape, buckwheat, onion and fiddleneck were cultivated with conventional methods. All the crops were grown with and without soil amendment with peat. Earthworms were sampled twice: 4 and 28 months after establishment of the experiment. In the former case part of the experimental plots were soil sampled and hand sorted for estimation of earthworms. In the latter case all experimental plots were sampled and both soil sampling and mustard extraction was carried out. Soil organic carbon and microbial biomass was measured at 14 and 28 months. Peat increased the abundance of juvenile Aporrectodea caliginosa by 74% in three growing seasons, but had no effect on adult numbers. Lumbricus terrestris numbers were not increased by peat treatment. Three season cultivation of caraway favoured both A. caliginosa and L. terrestris. An equal abundance of A. caliginosa was also found in plots cultivated with turnip rape and fiddleneck. Total earthworm and especially A. caliginosa numbers were very small in plastic-mulched strawberry beds. This was mainly attributed to repeated use of the insecticide endosulfan. With the strawberry plots omitted there was a significant correlation between soil microbial N measured at 14 months and juvenile Aporrectodea spp. and Lumbricus spp. numbers measured at 28 months. Adult earthworm numbers were not associated with either soil organic C or microbial biomass.     

Estimating genetic erosion in landraces — two case studies

Summary The results of collecting missions in Albania in 1941 and 1993 and in South Italy in 1950 and in the eighties allowed a comparison to be made of the material cultivated. The number of landraces still cultivated recently, as compared to their former number, was the basis for the estimation of genetic erosion. Genetic erosion (GE) was calculated as GE=100%-GI (Genetic integrity). Genetic erosion was found to be 72.4% in Albania and 72.8% in South Italy, respectively. These results prove the high degree of genetic erosion in landraces from different parts of the Mediterranean area. Apart from the economic conditions, several other factors are responsible for genetic erosion, among them breeding system, crop type (i.e., garden or field crop) and crop group (e.g., cereals, vegetables and pulses).The results show that in the areas investigated there are still landraces for in situ conservation. Ex situ conservation in genebanks proved to be a possibility. An integration process is necessary to prevent losses in crops which are difficult to propagate under ex situ conditions. The complementarity of both conservation methods is stressed.     

Genetic variation among populations of wild safflower, <Emphasis Type="Italic">Carthamus oxyacanthus</Emphasis> analyzed by agro-morphological traits and ISSR markers

Wild species of safflower, Carthamus oxyacanthus Bieb., is highly crossable with cultivated species, C. tinctorius L. and could be directly exploited in broadening safflower gene pool and improving the crop for biotic and abiotic stress environments. In this study, genetic diversity among accessions of C. oxyacanthus and their relationships with cultivated safflower were evaluated using agro-morphological traits and polymorphic inter-simple sequence repeats (ISSR) markers. Significant variation was observed among accessions particularly for seeds per capitulum, seed yield per plant, harvest index and capitula per plant. Cluster analysis based on agro-morphological traits classified the wild accessions in two groups according to their geographical regions, and separated them from the cultivated genotypes. ISSR marker also revealed a high genetic variation among the accessions, and cluster analysis based on this marker divided genotypes into four groups, with cultivated ones in a separate clade. Genetic variation observed among the wild safflower germplasm at the DNA level was higher than the agro-morphological traits, indicating that ISSR is an effective marker system for detecting diversity among safflower genotypes and their genetic relationships. Accessions of C. oxyacanthus with high genetic relationship to cultivated species could be used for interspecific hybridization in breeding programs of safflower.