环境影响因子对玉米芽中辅酶Q10含量的影响

探讨了玉米芽中影响辅酶Q₁₀含量的环境因子以及辅酶Q₁₀的提取新方法。结果表明:光和水环境因子影响较大,在受到水或光因子胁迫时,玉米芽中辅酶Q₁₀有较明显的增长趋势;玉米芽中辅酶Q₁₀的初步提取方法为采用70%乙醇同鲜活玉米芽混合进行鲜磨匀浆萃取,固液分离后残渣再用氯仿超声提取3次为最佳提取方法。     

三种玉米蚜虫种群的生态位分析

对重庆市郊区1998～1999年春玉米上3种蚜虫种群的数量动态、生态位宽度和生态位重叠进行了系统的分析研究．结果表明,发生在春玉米上的玉米蚜(Rhopalosiphum maidis),禾谷缢管蚜(Rhopalosiphum padi)和麦长管蚜(Sitobion avenae)3种蚜虫混合种群的种群数量消长呈现出5月中下旬和6月下旬两个高峰;在生态位宽度上,Livens生态位宽度指数(Bi)分析表明,麦长管蚜表现出时间上的高度分化,玉米蚜表现出空间上的高度聚集特性,而禾谷缢管蚜的分化并不明显;在生态位重叠上,玉米蚜和禾谷缢管蚜的HturlbeIt生态位重叠指数(Lij)最高,玉米蚜和麦长管蚜次之,禾谷缢管蚜和麦长管蚜最小．在春玉米上发生的3种蚜虫中,玉米蚜具有较强的竞争优势．     

盐胁迫对玉米叶片叶肉细胞生物膜超微结构的影响

研究了NaCl胁迫对玉米叶肉细胞生物膜超微结构的影响. 结果表明：NaCl胁迫破坏了玉米叶片叶肉细胞生物膜的正常结构,50 mmol·L^-1 NaCl处理胁迫下,玉米叶肉细胞核膜,线粒体膜,细胞膜,叶绿体膜,液泡膜都受到不同程度的破坏,叶绿体基粒类囊体膨胀,间质片层空间增大,片层紊乱。100 mmol·L^-1 NaCl处理胁迫下,质膜,液泡膜,线粒体,叶绿体都受到严重的破坏。细胞质膜破坏,破损的叶绿体充斥在细胞间隙中;叶绿体外膜破坏,甚至解体消失,叶肉细胞中充满膜结构,基粒排列方向改变,垛叠层数减少,基粒和基质片层界限模糊不清,有的基粒解体消失,甚至叶绿体完全解体;核膜破坏、解体,核中的染色质高度凝缩;线粒体的数量增多,线粒体膜破坏,脊的数量减少,甚至整个线粒体破损解体;液泡膜破坏;由于各种生物膜的破坏,使细胞内充满许多囊状小泡、多泡体或斑层小体;叶肉细胞发生严重的质壁分离,严重时发生细胞壁断裂;甚至整个细胞溶解。     

Recombinant near-isogenic lines: a resource for the mendelization of heterotic QTL in maize

Although heterosis is widely exploited in agriculture, a clear understanding of its genetic bases is still elusive. This work describes the development of maize recombinant near-isogenic lines (NILs) for the mendelization of six heterotic QTL previously identified based on a maize (Zea mays L.) RIL population. The efficient and inexpensive strategy adopted to generate sets of NILs starting from QTL-specific residual heterozygous lines (RHLs) is described and validated. In particular, we produced nine pairs of recombinant NILs for all six QTL starting from RHLs F_4:5 originally obtained during the production of the RIL population mentioned above. Whenever possible, two different NIL pairs were generated for each QTL. The efficiency of this procedure was tested by analyzing two segregating populations for two of the selected heterotic QTL for plant height, yield per plant and ears per plant. Both additive and dominant effects were observed, consistently with the presence of the QTL within the introgressed regions. Refinement of QTL detection was consistent with previous observations in terms of effects and position of the considered QTL. The genetic material developed in this work represents the starting point for QTL fine mapping aimed at understanding the genetic bases of hybrid vigor in maize. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Plant seeds as bioreactors for recombinant protein production

Plants are attractive expression systems for the economic production of recombinant proteins. Among the different plant-based systems, plant seed is the leading platform and holds several advantages such as high protein yields and stable storage of target proteins. Significant advances in using seeds as bioreactors have occurred in the past decade, which include the first commercialized plant-derived recombinant protein. Here we review the current progress on seeds as bioreactors, with focus on the different food crops as production platforms and comprehensive strategies in optimizing recombinant protein production in seeds.     

A tale of two centromeres—diversity of structure but conservation of function in plants and animals

The structural and functional aspects of two specific centromeres, one drawn from the animal kingdom (Drosophila) and the other from the plant kingdom (maize), are compared. Both cases illustrate an epigenetic component to centromere specification. The observations of neocentromeres in Drosophila and inactive centromeres in maize constitute one line of evidence for this hypothesis. Another common feature is the divisibility of centromere function with reduced stability as the size decreases. The systems differ in that Drosophila has no common sequence repeat at all centromeres, whereas maize has a 150-bp unit present in tandem arrays together with a centromere-specific transposon, centromere retrotransposon maize, present at all primary constrictions. Aspects of centromere structure known only from one or the other system might be common to both, namely, the presence of centromere RNAs in the kinetochore as found in maize and the organization of the centromeric histone 3 in tetrameric nucleosomes.     

Occurrence of fumonisins in maize imported into Iran during 2001–2002

Fumonisins, fungal toxins found primarily in maize and produced by various Fusarium species, have been shown to cause a variety of significant adverse health effects in livestock and experimental animals, and are probable human carcinogens. Thirty-three maize samples were collected at ports from bulk shipments, which were imported into Iran from six countries during 2001–2002, and analysed by HPLC for the most abundant of the naturally occurring fumonisin analogues, namely fumonisins B₁ (FB₁), B₂ (FB₂) and B₃ (FB₃). Of the 33 samples, 21 (64%) were found to contain FB₁ (58–512 μg/kg) at levels above 10 μg/kg. The frequency of FB₁ found in maize samples imported from Uruguay and Canada was 75%, followed by China and Argentina (67%), USA (60%), and Brazil (50%). The average FB₁ level was 266 and 169 μg/kg for positive and all samples, respectively. Medians were 250 and 146 μg/kg for positive and all samples, respectively. FB₂ levels ranged from not detected (<10 μg/kg) to 53 μg/kg, whereas no sample had an FB₃ level above the detection level (10 μg/kg). This is the first report of fumonisin contamination of imported maize in Iran. Although, the level of all detected fumonisins were below the Iranian and FDA tolerance levels for foods and feeds, It is necessary to maintain the strict rules to ensure continued safety of imported maize.     

酶促和非酶促抗氧化系统在玉米胚脱水耐性获得中的作用

以发育中的玉米胚为材料,研究了玉米胚脱水耐性的发育变化及其与抗氧化系统之间的关系。结果表明,授粉后18d的胚获得萌发能力,但不耐脱水;授粉后36d的胚开始获得耐脱水能力,并随着发育逐渐增加。随着发育,胚的超氧化物歧化酶（SOD）、抗坏血酸过氧化物酶（APX）、谷胱甘肽还原酶（GR）和脱氢抗坏血酸还原酶（DHAR）的活性逐渐降低,过氧化氢酶（CAT）活性逐渐增加。授粉后16～22d的玉米胚中检测不到抗坏血酸,24d后胚中抗坏血酸的含量显著增加;还原性谷胱甘肽含量在整个发育过程中逐渐增加。脱水胚的SOD、APX和DHAR的活性比对照（未脱水）胚低,而GR和CAT活性在发育早期比对照胚低,在发育中、后期高于对照胚。脱水胚的抗坏血酸和还原性谷胱甘肽含量明显低于对照胚。胚中丙二醛的含量随着发育逐渐下降,脱水胚的丙二醛含量显著高于对照。这些结果说明CAT活性和谷胱甘肽含量的增加以及脂质过氧化产物丙二醛含量的下降与玉米胚脱水耐性的获得密切相关。     

玉米种质资源抗矮花叶病鉴定

采用摩擦接种方法,鉴定了3995份玉米种质对玉米矮花叶病毒(SCMV-MDB)的抗病性。经重复鉴定,筛选出抗病优良自交系73份,抗病丰产杂交种80份。玉米不同类群种质,对SCMV-MDB的抗病性有明显差异,改良Reid、Lancaster、旅大红骨类群种质大部分表现感病;塘四平头、外杂先锋选系类群种质大多数表现抗病。在不同类型种质中,硬粒型、马齿型和半马齿型表现抗病的较多,糯质型较少,甜质型和爆裂型中尚未发现抗源。