作物种子胚乳中等位基因多态性表达

本文综述了作物种子胚乳中等位基因表达多态性的研究进展，介绍了基因组印记现象及其对作物种子胚乳性状的表观遗传及种子发育的影响。     

凤眼莲的胚胎学研究Ⅲ.受精作用和胚胎发育

本文报道了凤眼莲的受精过程及胚和胚乳的发育。授粉后3～8小时,花粉管穿过花柱;17～21小时,花粉管经珠孔到达胚囊;约48小时,一个精子进入卵细胞;3天完成受精作用;5天出现两细胞原胚。胚的发育属紫菀型,经历原胚、球型胚、椭圆形胚、凹形胚、棒形胚等各个时期。凤眼莲的胚乳发育属沼生目型,授粉后约19～21小时,另一精于与次生核融合形成游离核;2～5天形成大量的胚乳游离核;6天开始形成胚乳细胞壁。约20～21天,种子成熟,种子含胚和胚乳。     

诱发谷物胚乳突变的研究进展

谷类作物的胚乳是人类食粮和许多生活必需品的主要来源。通过诱发胚乳突变改良谷物品质，已成为作物育种的发展方向之一。本文综述诱发玉米，水稻和麦类等主要谷类作物胚乳突变的研究进展，以推动有关工作的开展。     

银杏种子辐照效应及其保鲜的初步研究

不同剂量^60Coγ射线处理去外种皮的银杏种子,50Gy以上剂量处理的种子不能发芽,种胚活力迅速下降而趋于死亡,800Gy以下剂量处理后,胚乳仍保持较长时期的活力。2000Gy以上剂量使种子失水加快,胚乳失活且变软腐烂,共电导率迅速上升,辐照处理使银杏降种子的呼吸受到较大抑制,有利于贮藏保鲜,银杏种子密封包装后,经50－200Gy辐照工在室内常温存放,含水量40．25％的银杏种子的保质期为2－3个月,当种子含水量降至35．96％时,保持期可达4－6个月。     

滚筒式作物种子干燥机自动控制装置的研制

作物种子干燥对种子的安全、保纯、适应性、温度控制精度的要求较高，为此设计了滚筒式作物种子干燥机及以单片机为核心的控制装置。分析了自行研制的滚筒式作物种子干燥机的结构及工作原理，讨论了其自动控制装置在种子干燥过程中的作用及工作原理，介绍了所设计的单片机自动控制装置的硬件电路和控制程序。使用结果表明：该控制装置设计合理，干燥的均匀性好，速度快、能保证种子的纯度，能满足不同作物种子在干燥过程中的安全性及控制精度的要求。     

重离子束注入小麦胚乳诱发的突变效应

采用 75MeV u16O8+ 离子 (降能至 36MeV u ,使其在胚乳中的射程约为 2 4mm ) ,从种子顶部垂直注入胚乳 ,通过“嫁接”技术后进行萌发。处理后观测结果表明 ,当代根尖细胞染色体的微核率和畸变率与注入剂量呈正相关 ;测定了当代抗氧化酶活性、丙二醛 (MDA)含量和蛋白质含量的变化 ;经多代大田培育获得了矮杆与各种穗型的变异 ,且具有遗传性。结果显示离子注入胚乳不仅对生物的修复系统有较大影响 ,而且能够诱发后代突变。     

四倍体刺槐种子形态及结构变异研究

对四倍体刺槐种子进行观测和解剖,结果证明：四倍体刺槐种子单粒重、有胚率和萌发率分别是二倍体刺槐的26.3%、30.1%和6.3%;单粒重10mg以上的种子（比例4.41%）萌发率达62.28%,小于7mg（比例84.97%）的种子就完全失去了萌发力。四倍体刺槐种胚重量、胚乳重量、种皮重量及三者的构成比例均明显不同于二倍...     

利用糊粉层激素敏感性筛选小麦α-淀粉酶变异体

以小麦种子为试材,研究筛选种子胚乳糊粉层中α-淀粉酶调控机制变异体的方法。应用这种方法,在花培纯系内籽粒间未发现变异;在体细胞无性系的籽粒间发现了对激素敏感性改变的变异体。表明了该筛选方法的可行性。 本文还对适宜的试验条件和筛选指标作了探讨。     

异源表达Hvsusiba2基因提高水稻胚乳淀粉含量的研究

大麦糖信号诱导转录因子(sugar signaling in barley,Hvsusiba2)作用于淀粉合成途径的上游,是大麦(Hordeum vulgare)淀粉合成途径的关键调控因子。本研究将Hvsusiba2基因构建在淀粉分支酶基因启动子pSBEⅡb下游,利用启动子的胚乳优势表达特性,驱动Hvsusiba2在胚乳中表达,增加水稻(Oryza sotiva)胚乳总淀粉含量。采用农杆菌(Agrobacterium tumefaciens)介导获得转化株系。对2个单拷贝整合转基因株系相关基因转录分析显示,Hvsusiba2基因在水稻茎、叶及种子中均能正常转录。与支链淀粉合成相关基因(淀粉分支酶基因(starch branching enzyme,OssbeⅡb)、异淀粉酶基因(isoamylase,Osiso1)及蔗糖转运蛋白酶基因(sucrose transporter,Ossut1))在3个组织中的转录高于对照2倍以上;蔗糖合成酶基因(sucrose synthase,Ossus2,Ossus3)和蔗糖转运蛋白基因(Ossut5)在茎和种子中的表达显著增强(P0.05)。蔗糖合成酶基因(Ossus1)、尿苷二磷酸葡萄糖焦磷酸化酶基因(UDP-glucose pyrophosphorylase,Osugp1)和淀粉分支酶基因(OssbeI)在茎和叶中的表达明显增强(P0.05)。两个株系成熟种子中淀粉含量分别由77.73%提高到86.49%和85.15%。研究结果表明,水稻异源表达Hvsusiba2基因是通过提高部分淀粉合成相关基因在种子中的表达来提高种子淀粉含量的。研究结果为利用分子手段提高水稻胚乳淀粉含量提供了理论依据。     

水稻醇溶蛋白4a基因启动子在转基因水稻中的特异性表达

利用ＰＣＲ方法从水稻“中花８号”基因组中扩增出醇溶蛋白４ａ基因启动子后,将其与ＧＵＳ基因融合,通过基因枪法导入水稻“台北３０９”中。对转基因水稻植株进行的组织化学分析表明,ＧＵＳ基因特异性在种子的胚乳中表达,而在其它的组织中没有表达。水稻醇溶蛋白基因４ａ启动子的胚乳特异性表达可以稳定遗传到下一代。     

Protein metabolism in rice seedling

The relationship between protein synthesis and degradation in germinating rice seed were studied with protein synthetic inhibitors. Both DNP and 8-AG inhibited the degradation of glutelin, the major storage protein in rice seed, while the inhibitors had no direct effect in the activity of rice seed proteinllse in vitro. The prevention can be partly ascribed to the Inhibition of proteinase synthesis because the inhibitors depressed the increase in proteinase activity during germination. When DNP treatment was started at the onset of germination, the degradation of glutelin in the endosperm was seriously inhibited and the endosperm remained rigid over 9 days of incubation at 30°C. In contrast, the inhibition was less efficient clent when the treatment was started in the later stage. It is suggested that the degradation of the storage protein in rice seed depends on the synthetic process of the hydrolytic enzymes which increase during germination. disintegrate the compartmentation of the endosperm and allow the storage proteins to come in contact with the existing proteinases     

Effect of sowing methods and sowing rate in organic seed production of timothy (Phleum pratense L.), meadow fescue (Festuca pratensis Huds.) and red clover (Trifolium pratense L.)

Different sowing methods and sowing rates were evaluated in organic seed production of timothy (two trials), meadow fescue (two trials) and red clover (one trial) in Southeast Norway, during 2010–2013. The plan included: (1) broadcast sowing of grass/clover, cover crop sown at 12 cm row distance; (2) sowing of cover and seed crop in crossed rows, both at 12 cm row distance; and (3) sowing of cover crop and seed crop in every other row. The three sowing rates were 5, 10 and 15 kg ha–1 in timothy and meadow fescue and 3, 6 and 9 kg ha–1 in red clover. On average for sowing rates and all trials with timothy, meadow fescue and red clover, first year’s seed yields were 5–6%, 20–25% and 19–25% higher on plots sown with cover crop and seed crop in every other row than on plots where seed crop had been broadcast or sown perpendicularly to the cover crop. The different sowing methods had no effect on weed coverage or weed contamination in the cleaned seed. Increasing sowing rate usually had a negative influence on seed yield, while weed coverage/contamination was not significantly affected. It is concluded that organic seed crops should be established with cover crop and seed crop in every other row at a low sowing rate. However, in an organic production system, even this favorable method will not always be sufficient to meet the requirement for seed crop purity.     

Collection and characterization of yellow endosperm sorghums from West Africa for biofortification

Sorghum is a good candidate crop for breeding to increase provitamin A, i.e., biofortification. Yellow endosperm sorghums contain carotenoids, including precursors of vitamin A, and sorghum is a major staple crop in areas of Asia and Africa where vitamin A deficiency is prevalent. Our objective was to collect and characterize yellow endosperm sorghums as a potential new source of genetic diversity to increase provitamin A content. A set of 164 landraces were collected from southern Niger and northern Nigeria. The most important use of these cultivars was as food. The endosperm exhibited a significant variation in yellow intensity. Lutein, zeaxanthin and β-carotene were the most abundant carotenoids in the ten landraces with the most intense yellow color. Cluster analysis, principal coordinate analysis and population differentiation test revealed that this set of 164 landraces represent a new genetic pool that might increase the genetic diversity of yellow endosperm sorghums in applied breeding programs.     

Comparative proteomical analysis of zygotic embryo and endosperm from Coffea arabica seeds

During coffee seed development, proteins are predominantly deposited in cotyledons and in the endosperm. Reserve proteins of the 11S family are the most abundant globulins in coffee seeds, acting as a nitrogen source during roasting and guaranteeing flavor and aroma. The aim of the present study was to compare the protein profiles of endosperm and zygotic embryos of coffee seeds. Proteins were extracted from whole seed as well as from embryo and endosperm, separately. Total proteins were analyzed by two-dimensional electrophoresis (2-DE) followed by identification by mass spectrometry (MS). The most abundant spots observed in the gels of coffee seeds were excised, digested with trypsin, and identified by MS as subunits of the 11S globulin. Spots with identical pI and molecular masses were also observed in the protein profiles of coffee endosperm and embryo, indicating that 11S protein is also highly expressed in those tissues. Peptide sequence coverage of about 20% of the entire 11S globulin was obtained. Three other proteins were identified in the embryo and endosperm 2-DE profiles as a Cupin superfamily protein, an allergenic protein (Pru ar 1), exclusive to the endosperm 2D map, and a hypothetical protein, observed only in the zygotic embryo profile.     

Extraction of recombinant dog gastric lipase from transgenic corn seed

Several approaches were examined for extracting the relatively hydrophobic protein recombinant dog gastric lipase (rDGL) expressed in the endosperm of transgenic corn seed. The first approach used minimal processing of the seed before extraction (i.e. simple grinding of whole seed) followed by selective extraction to eliminate 72% of contaminant proteins without compromising rDGL recovery from the meal of whole grain. The second approach added defatting of the whole grain meal to reduce the amount of detergent in the subsequent step for extracting rDGL. The third approach incorporated dry-milling of the corn to recover an endosperm rich fraction, followed by extraction of this fraction. The dry milling strategy was most effective, resulting in recovery of 35 U rDGL/g of corn seed (50 U/g of endosperm) with a specific activity of 9 U/mg compared to 22 U and 3 U/mg for the first strategy and 36 U and 3.7 U/mg for the second. The reductions in host protein contamination and lower detergent levels of the endosperm route should simplify downstream purification steps.     

A review of factors that influence the production of quality seed for long-term conservation in genebanks

Seed quality is a critical aspect in agriculture as well as in the long-term conservation of plant genetic resources in genebanks. Since potential seed longevity depends on initial quality, genebank curators need to be aware of the best management practices that contribute to the production of high quality seed during routine germplasm regeneration/multiplication. Among the factors influencing initial seed quality, those related to crop management, including plant nutrient and water supply during crop growth, climatic conditions during seed development and maturation, as well as the harvest and drying practices are of considerable significance. Seeds of high quality can be obtained by planting in suitable areas/fields and at appropriate times, applying good crop management practices, adoption of proper harvesting and drying techniques, careful handling and processing to minimize mechanical injuries and unwanted seed mixing with other accessions, and ensuring minimum deterioration before reaching the designated storage. However, seed production and post-harvest handling highly depend on the biology and agronomy of the species. As germplasm collections contain a wide range of diversity for morphological and agronomic characters and that there might well be critical gaps in knowledge among genebank staff or about the species in question, genebanks may also need to embark on research to gain crop specific knowledge on optimal seed production procedures to improve seed quality.     

SPATIAL DISTRIBUTION AND ACCUMULATION OF CALCIUM IN DIFFERENT TISSUES,DEVELOPING SPIKES AND SEEDS OF FINGER MILLET GENOTYPES

□ Total calcium (Ca) content in different tissues, developing spikes (S1, S2, S3 and S4 stages), and distribution sites in seeds of five finger millet genotypes, which were differed in total calcium content, were analyzed. Atomic absorption spectroscopy (AAS) revealed stage-dependent quantitative changes in calcium accumulation from low to high during different stages of developing spikes and also in different tissues and grains. Results of scanning electron microscopic (SEM) energy dispersive X-ray (EDX) analysis showed differential distributions of the calcium in seed components viz. seed coat, aleurone layer and endosperm. Highest calcium content was observed in aleurone layer followed by seed coat while lowest calcium was found in endosperm of all genotypes. Major differences were found amongst genotypes with regard to the calcium distribution in seed components. The differential regulation of transport machinery might be responsible for differential calcium ion delivery and spatial distribution in the seed. A clear understanding of differential accumulation, spatial distribution and the variation of calcium within finger millet genotypes/seeds could be exploited for breeding for their bio-fortification and development of calcium rich functional foods.