农杆菌介导的小麦成熟胚遗传转化影响因素分析

为解决农杆菌介导的小麦成熟胚遗传转化效率较低的难题,以春小麦Bobwhite成熟胚为外植体,分析植物激素、愈伤组织预培养时间、侵染时间和共培养阶段干燥处理对小麦成熟胚愈伤组织遗传转化的影响,并在遗传转化处理中辅以3个组织再生相关基因(TaSERK1、TaSERK2、TaNiR)的qRT-PCR分析。结果表明,愈伤组织预培养阶段添加适量的2,4-D和Picloram均可诱导成熟胚愈伤组织的形成,但是2mg·L~(-1)Picloram培养基中愈伤组织的胚萌发率为20.78%,远高于2,4-D诱导的胚萌发率(11.38%);共培养阶段对农杆菌侵染的愈伤组织进行干燥处理能适当提高愈伤组织的转化效率;qRT-PCR分析发现再生相关基因TaNiR相对表达量的增加能适当提高愈伤组织的转化率。     

基本培养基及激素对野生一粒小麦幼胚培养的影响

为建立适于野生一粒小麦遗传转化的高效组培再生体系,以野生型一粒小麦幼胚为外植体,研究了MS、MSE3和N6三种基本培养基和激素对愈伤组织诱导、分化和成苗的影响。结果表明,愈伤诱导培养基以MES3为基本培养基并添加2.0mg·L~(-1) 2,4-D效果最佳,愈伤组织出愈率最高可达90.5%,胚性愈伤率为80.0%。愈伤组织分化过程在添加0.25mg·L~(-1) IAA的MS培养基中加入0.5mg·L~(-1) 6-BA分化效果最佳,分化率能达到50.7%,成苗率为26.5%。     

二穗短柄草成熟胚再生体系建立及农杆菌介导转化研究

为建立二穗短柄草组织培养及遗传转化体系,以二穗短柄草BD21-3成熟胚为外植体,对成熟胚愈伤诱导、分化以及农杆菌侵染条件进行了研究。结果表明,在含有2.5mg·L~(-1) 2,4-D的培养基上,愈伤组织出愈率最高为93.83%;在含有0.2mg·L~(-1) KT的分化培养基上,分化率最高为38.18%;对二穗短柄草胚性愈伤组织农杆菌转化和GUS染色结果表明,侵染的过程中农杆菌菌液浓度OD_(600)为0.6、侵染时间为5min时转化率最高。     

大麦单粒种子起源的小孢子培养再生频率研究

为提高单株小孢子培养的再生效率,以大麦品种花30为材料,在人工气候室研究了离体穗、离体小花预处理时间和诱导培养基中无机氮、有机氮含量以及添加PEG对愈伤组织产量、绿苗产量和再生能力的影响。结果表明,离体穗5℃处理19 d的愈伤组织和绿苗产量及再生能力均优于32 d的,离体小花预处理1～2 d可促进愈伤组织的形成和绿苗的分化;降低无机氮浓度[KNO_3降至707.5 mg·L~(-1),(NH_4)_2SO_4降至115.75 mg·L~(-1)]可提高愈伤组织和绿苗产量及再生能力;提高有机氮浓度(谷氨酰胺从400 mg·L~(-1)提高到1 600 mg·L~(-1),水解酪蛋白从100 mg·L~(-1)提高到400 mg·L~(-1))可增加小孢子愈伤组织和绿苗产量;培养基中添加4%PEG可提高小孢子愈伤组织产量和质量。     

节节麦幼胚再生体系的建立

为建立高效的节节麦幼胚再生体系,以节节麦幼胚为外植体,通过正交设计,探索基本培养基、2,4-D、碳源、KT等因素对幼胚愈伤组织诱导、分化及植株再生效果的影响。结果表明,4种因素中,基本培养基对节节麦幼胚愈伤组织诱导的影响最显著(P0.05),2,4-D浓度对节节麦幼胚愈伤组织诱导也有显著影响(P0.05),添加3.0mg·L~(-1) 2,4-D的培养基诱导出的愈伤组织质量高,淡黄色,表面呈不规则颗粒状,质地致密,再生频率可以达到17.62%。KT浓度对节节麦愈伤分化影响最显著,基本培养基、2,4-D和碳源对节节麦幼胚愈伤分化均无显著影响。不同碳源对节节麦幼胚愈伤组织诱导和分化的影响均不显著,为节约成本可直接选用30g·L~(-1)蔗糖作为碳源。节节麦幼胚组织培养的最佳组合是:愈伤诱导培养基为MS培养基+3mg·L~(-1) 2,4-D+15g·L~(-1)蔗糖+15g·L~(-1)甘露醇,愈伤分化培养基为MS培养基+15g·L~(-1)蔗糖+15g·L~(~(-1))甘露醇+1.0mg·L~(-1) KT。     

农杆菌介导的小麦成熟胚转化的影响因素

为了研究农杆菌介导的小麦成熟胚转化的影响因素,以6个小麦品种成熟胚为外植体进行离体培养,以EHA105和LBA4404农杆菌为供体(含有pCAMBIA1305双元载体)材料,研究了诱导培养基、分化培养基、农杆菌菌株、愈伤组织诱导培养时间、农杆菌菌液浓度和侵染时间对小麦成熟胚愈伤组织诱导、分化、再生的影响。结果表明:(1)以小麦品种小偃22的成熟胚为材料,获得最佳的诱导培养基方案(MS+2mg.L-1 2,4-D+0.5mg.L-1 KT+500mg.L-1水解酪蛋白+150mg.L-1天门冬酰胺)和分化培养基方案(MS+2mg.L-1 ZT+0.5mg.L-1 KT);(2)6个小麦品种中,洛阳8176和张掖春小麦具有较强的再生能力,筛选培养后较多的愈伤组织分化出小绿点;(3)洛阳8716和张掖春小麦的成熟胚,经愈伤组织诱导培养6-7d,农杆菌侵染后愈伤组织再生能力强;(4)农杆菌侵染后愈伤组织的再生能力与农杆菌菌株的关系不明显,而与小麦品种基因型、侵染时间和菌液浓度有较明显的关系;(5)以小麦洛阳8716和张掖春小麦成熟胚愈伤组织为受体,黑暗条件下诱导培养6-7d,在24±1℃黑暗条件下共培养3d和500mg.L-1羧苄青霉素(Cb)除菌及10mg.L-1潮霉素筛选处理后,共得到分化植株23株,其中以洛阳8716为受体材料,由农杆菌LBA4404和EHA105转化得到的植株分别为11株和4株,植株分化率分别为3.57%和1.31%;以张掖春小麦为受体材料,由农杆菌LBA4404和EHA105转化得到的植株分别为5株和3株,植株分化率分别为1.57%和1.14%。     

α-硫辛酸对大豆农杆菌介导GUS瞬时表达和芽诱导的影响

以适宜转化大豆受体YC-2为材料,研究了抗氧化剂α-硫辛酸对农杆菌介导GUS瞬时表达和芽诱导率的影响.结果表明:在共培养基中添加不同浓度的抗氧化剂可显著降低外植体的褐化率,随α-硫辛酸浓度的增加外植体褐化率明显减少,但白化率增加,且这些白化的外植体在后期不易产生诱导芽;共培养中添加不同浓度的α-硫辛酸可增强GUS瞬时表...     

提高农杆菌转化水稻频率几个因素的研究

以6个重要的籼稻和粳稻品种为材料,研究了影响农杆菌转化水稻频率的几个重要因素。结果表明,对于籼稻品种而言,CC培养基是愈伤组织的最适诱导培养基;添加1.0~2.0 mg/L ABA能有效地改善愈伤组织的质量;在继代培养基中添加山梨醇能改善愈伤组织的生长状态,降低愈伤组织的褐化。而对于粳稻品种来说,适宜的诱导培养基是NB培养基,添加ABA对愈伤组织的改善效果不明显,对于多次继代的愈伤可以适当增加蔗糖浓度以提高抗性愈伤率。此外,在筛选时期适当加大筛选压力,分化时去掉筛选压力,壮苗时加适当的选择压力,可提高转化率。在分化时,采用适宜的激素配比有利于提高分化率。应用所优化的农杆菌转化系统,获得了一些有价值的转化植株。     

玉米成熟胚愈伤组织诱导及褐化控制研究

玉米成熟胚组织培养过程中发生褐化可影响愈伤组织的诱导、生长和组培过程的进行。实验研究探讨3种防褐剂硝酸银(AgNO3)、活性炭和PVP及培养条件对玉米成熟胚愈伤组织诱导和继代过程中褐化控制的作用。结果表明,一定浓度的AgNO3能明显减轻褐化,其中愈伤组织诱导时10.0 mg/LAgNO3控制外植体褐化的效果最佳;愈伤组织继代培养时7.0 mg/LAgNO3控制较为适宜。2.0 g/L活性炭能有效抑制外植体的褐化,高于此浓度会抑制愈伤组织的诱导;继代培养初期在含2.0 g/L活性炭的培养基中培养7 d,不仅能有效控制褐化,还在一定程度上促进了愈伤组织的生长。愈伤组织诱导时1.0 g/LPVP能在有效控制外植体褐化的同时促进愈伤组织的形成。暗培养能显著减轻褐化的发生,有利于愈伤组织的诱导。     

外源脱落酸缓解小麦幼苗铜胁迫伤害的生理机制初探

为了解脱落酸(ABA)缓解小麦幼苗铜胁迫伤害的生理机制,采用营养液培养方法,研究了外源ABA对0.5mmol·L~(-1) Cu~(2+)胁迫下小麦幼苗叶绿素、可溶性糖含量及抗氧特性的影响。结果表明,0.5mmol·L~(-1) Cu~(2+)胁迫对小麦幼苗伤害明显,降低了叶片叶绿素和可溶性糖含量及根、叶片超氧化物歧化酶(SOD)活性,提高了根和叶片丙二醛含量。铜胁迫下,添加1μmol·L~(-1) ABA可显著提高小麦幼苗叶片叶绿素和可溶性糖含量及根和叶片过氧化物酶(POD)、叶片SOD活性,降低叶片铜含量。说明适宜浓度的外源ABA可通过调节渗透调节物质含量、增强抗氧化酶活性来减轻铜胁迫对小麦幼苗的伤害,提高其抗铜胁迫能力。     

Comparative Assessment of the Efficacy of Various Nitrogen Fertilizers

Summary

The efficiency of N fertilizers is usually poor; often less than 50% of the applied N is taken up by the crop. This review focuses on various N fertilizers with respect to the significance of different N loss pathways, namely (i) ammonia volatilization, (ii) dinitrogen and nitrogen oxide emissions, and (iii) nitrate leaching. Further, the significance of biological N immobilization, ammonium fixation and, finally, the impact of nitrate vs. ammonium uptake on crop yield are also discussed. The reviewed literature shows that N fertilizers may differ markedly in their susceptibility to losses. There is, however, considerable scope to improve N efficiency of each N source by proper N management practices.     

Novel food and non-food uses for sorghum and millets

Sorghum and millets have considerable potential in foods and beverages. As they are gluten-free they are suitable for coeliacs. Sorghum is also a potentially important source of nutraceuticals such antioxidant phenolics and cholesterol-lowering waxes. Cakes, cookies, pasta, a parboiled rice-like product and snack foods have been successfully produced from sorghum and, in some cases, millets. Wheat-free sorghum or millet bread remains the main challenge. Additives such as native and pre-gelatinised starches, hydrocolloids, fat, egg and rye pentosans improve bread quality. However, specific volumes are lower than those for wheat bread or gluten-free breads based on pure starches, and in many cases, breads tend to stale faster. Lager and stout beers with sorghum are brewed commercially. Sorghum's high-starch gelatinisation temperature and low beta-amylase activity remain problems with regard to complete substitution of barley malt with sorghum malt . The role of the sorghum endosperm matrix protein and cell wall components in limiting extract is a research focus. Brewing with millets is still at an experimental stage. Sorghum could be important for bioethanol and other bio-industrial products. Bioethanol research has focused on improving the economics of the process through cultivar selection, method development for low-quality grain and pre-processing to recover valuable by-products. Potential by-products such as the kafirin prolamin proteins and the pericarp wax have potential as bioplastic films and coatings for foods, primarily due to their hydrophobicity.     

Evolutionary aspects of the trade-off between seed size and number in crops

Whereas the concept that availability of resources drives seed production is sound in principle, it is incomplete as there are many solutions to the allocation of resources that derive from the trade-off between number and size. This paper examines evolutionary aspects of this trade-off in annual grain crops. The analysis is centred on the working hypotheses that, for a given species and environment, allocation of resources to reproduction involves (H1) high plasticity in seed number, which allows for variable resource availability, and (H2) a relatively narrow range of seed size that results from evolutionary and agronomic selection. Comparisons between crops and fish are used to highlight common evolutionary elements in taxa where parents provide little or no care to their offspring, with the consequence that both number and early survival of offspring, hence fitness of parents, are partially related to embryo size and reserves.

The plasticity of seed number in relation to availability of resources is analysed against the established relationship between offspring number and parent growth rate during critical stages. The notion that seed size is under stabilising selection is analysed against three conditions: (1) mean seed size is conservative for a given species and environment, (2) seed size affects fitness, and (3) seed size is heritable. Databases from published papers were compiled to analyse the relative variability of seed size and number, and the heritability of seed size. Evidence for and against the link between seed size and parental fitness is revised using the Smith–Fretwell model as framework (Am. Nat., 108, 499–506).

The proposal of high plasticity of seed number and narrow variability of seed size resulting from stabilising natural selection is generally consistent with evolutionary and genetic considerations. Agronomic selection may have reinforced natural selection leading to relatively narrow seed size in species such as wheat and soybean, where cultivated types retained high plasticity for seed number. In contrast, selection for one or few inflorescences in crops like sunflower and maize may have morphologically reduced seed number plasticity and increased variability of seed size and its responsiveness to resource availability in relation to their wild ancestors.     

Citrus Flavonoids in Fruit and Traditional Chinese Medicinal Food Ingredients in China

Flavonoids-enriched tissues of citrus such as peel, immature fruit and flower are consumed as culinary seasonings, tea ingredients in China for centuries. This HPLC quantitative study on the five citrus flavonoids, naringin, hesperidin, neohesperidin, sinensetin and nobiletin on a wide range of Chinese citrus fruits and several Traditional Chinese Medicinal food ingredients in East China, revealed a great diversity in flavonoid composition. Huyou peel (C. paradisi cv. Changshanhuyou) was found to be the best naringin (3.25%) and neohesperidin (2.76%) source; C. aurantium, a major ingredient of several citrus-related TCM, is also a suitable source of naringin and neohesperidin, and a good juice source for flavanone glycosides; the peel of Wenzhoumiju (C. unshiu) is one of the richest local species in hesperidin (up to 6.25%); Zaoju (C. subcompressa) has the highest content of nobiletin (0.59%), a polymethoxylated flavone. LC-ES-MS analysis of Zanthoxylum genus for flavonoids revealed for the first time the presence of significant amounts (0.74%) of hesperidin in the root of Liangmianzhen (Z. nitidum (Roxb.) DC), a relative of Sichuan pepper, which is a spice widely used in China.     

Effect of a continuous hot water treatment of potato tubers on seed-borne fungal pathogens

Summary The viability of five pathogens was decreased by treatment with hot water when tested in vitro.Polyscytalum pustulans was most sensitive andRhizoctonia solani least sensitive. Potato tubers were exposed to 55°C for 5 min in a commercial continuous hot water treatment plant using naturally contaminated seed tubers and tubers which had been inoculated by dipping in comminuted cultures. The frequency of eyes colonised byP. pustulans, Helminthosporium solani, andR. solani was reduced to virtually zero and the effect persisted on tubers subsequently stored at 4°C and at 15°C for up to 16 wk. Results withColletotrichum coccodes were inconclusive. Treatment suppressedPenicillium spp. which, however, rapidly recolonised the eyes during storage, leading to higher contamination levels in the treated than in the untreated tubers. With tubers inoculated withPhoma foveata, good control was achieved when the incubation period before treatment was 10 d but not when the period was 42 d.     

Role of Benzoxazinones in Cereals

Summary

Heterocyclic 1,4-benzoxazin-3-ones and related benzox-azolinones are important natural products of the cereal crops maize, wheat and rye. Much research has focused on the role of these compounds as defensive agents against plant diseases and pests. Studies of a wide variety of biological effects on herbivores and nematodes, plant pathogenic fungi and bacteria are reviewed in this article. Phytotoxic activity of the compounds is also considered with respect to allelopathic interaction with higher plants. Recent investigations of molecular aspects of interactions of cyclic hydroxamic acids and related benzoxazo-linones with acceptor organisms have demonstrated different effective detoxification strategies and tolerance mechanisms. This research has greatly advanced our knowledge about the multiple roles that these allelochemicals play in ecological systems.     

Potential of dry fractionation of wheat bran for the development of food ingredients,part I: Influence of ultra-fine grinding

Wheat bran is an undervalued by-product of white flour and has great nutritional potential due to its high content in fibres and bioactive compounds. Micronized bran could be used as a food ingredient to improve the nutritional potential of cereal products, or be used as a starting material for other processes (bioactive compound extraction or bran fractionation). The aim of this work was to find a way to efficiently decrease the particle size of bran. The influence of the grinding temperature (ambient or cryogenic grinding) on the granulometric distribution of particles, their composition, and their microstructure was studied, at lab-scale and pilot-scale. It showed that the intrinsic characteristics of bran (glass transition within intermediate layers at −46 °C) had more influence on its grinding behaviour than the type of grinding device used: the particles size distributions obtained after grinding at lab-scale and pilot-scale were very similar. At both scales, the granulometric curves were narrow for cryogenic grinding, while for ambient grinding they were spread over the whole particle size range. Ultrafine particles were obtained in both ambient and cryogenic conditions. Negative temperatures, by increasing the material’s brittleness, favoured a fast fragmentation of bran: one step of cryogenic grinding allowed a median particle size of nearly 50 μm to be reached, whereas three successive steps of ambient grinding were needed for the same result. On the other hand, ambient temperature favoured the dissociation of the different constituent layers of wheat bran, and produced less composite particles than cryogenic grinding.     

Multiple use of plants: Studies on selenium incorporation in some agricultural species for the production of organic selenium compounds

The technique of spraying plants with inorganic forms of selenium can be employed for phytochemical production of organic selenium compounds. Fractionation of the plant material makes it possible to produce a highly concentrated and well defined selenium supplement with potential use in animal and human nutrition. The fractionation also gives opportunities to combine production of organic selenium compounds with other products, for example plant fibres. Multiple use of plants can contribute to a more efficient utilization of land area (in comparison to monocultures solely adapted to food production). It also gives the opportunity to develop systems suitable for long term fixation of carbon, as long as the plant material is not reoxidised to carbon dioxide. Plant fibres could provide raw material for the production of paper or building materials in combination with the production of organic selenium compounds preferentially accumulated in another fraction of the processed plant.     

Biological factors influencing the transmission of potato leafroll virus by different aphid species

Summary Macrosiphum euphorbiae, collected in the field from potato plants infected with potato leafroll virus (PLRV), transmitted the virus to fewer potato plants in a field trial than did laboratory-rearedMyzus persicae. In the laboratory,M. persicae was the only efficient vector of PLRV fromPhysalis floridana seedlings, potato sprouts or excised leaves toP. floridana. Two clones ofM. euphorbiae and one clone ofAulacorthum solani transmitted PLRV from infected potato plants toNicotiana clevelandii as effeciently asM. persicae but a clone ofAphis gossypii was an inefficient PLRV vector. An isolate of PLRV, whichM. persicae transmitted inefficiently from potato toN. clevelandii, was also transmitted inefficiently byM. euphorbiae andA. solani.