转基因玉米育种研究进展

转基因性状包括抗虫、耐除草剂、耐干旱、雄性不育、高赖氨酸含量和耐热淀粉酶等。介绍了转基因玉米的转化途径、转基因玉米的功能基因及性状、转基因玉米的基因聚合方法以及目前美国市场上的主要转基因玉米性状、转基因玉米及其产品检测技术和转Bt基因玉米害虫的抗性治理,讨论转基因玉米基因专利失效以后的管理问题和转基因玉米基因发展趋势。     

不同林龄橡胶凋落物叶分解特性与有机碳动态研究

通过网袋法,研究一年内6 a、12 a、20 a、28 a共4组不同林龄橡胶凋落物叶分解及有机碳动态变化的过程。结果表明:(1)不同林龄橡胶凋落物叶均表现为慢-快-慢的分解趋势,经1 a的分解,4组林龄组橡胶凋落叶残留率分别为28.33%、30.53%、31.59%和33.89%。(2)不同林龄橡胶凋落物叶分解系数为1.376 2~1.608 8,平均值为1.498 2,大小顺序为6 a>12 a>18 a>28 a,分解50%和95%所需时间分别为0.43、0.45、0.47、0.50 a和1.86、1.96、2.03、2.18 a。(3)林龄显著影响橡胶凋落物叶初始N含量、P含量、木质素/N比、C/P比与木质素/P比,但对C含量、木质素含量及C/N比影响不明显。(4)初始C/N比极显著影响橡胶凋落物叶分解速率,而初始P含量对凋落物分解影响不显著(5)4组林龄组橡胶凋落物叶有机碳浓度是一个先上升后下降的过程,研究结束时,4组林龄橡胶凋落物叶有机碳分别释放了77.58%、79.41%、75.89%和75.02%,其动态变化过程显著符合一元多项式模型,决定系数(R2)在0.88以上。     

转Bt毒蛋白基因玉米及其抗虫性研究进展

本文从转Bt毒蛋白基因玉米的培育及商品化，Bt毒蛋白基因在转基因玉米中的遗传分离与整合、对玉米螟及其它害虫的杀虫效果、对天敌种群数量和玉米病害发生程度的影响、玉米螟对转Bt毒蛋白基因玉米产生抗性及解决措施、应用转Bt毒蛋白基因玉米潜在的生态风险性等方面对国内外最新研究进展进行了综述。     

西双版纳不同森林类型凋落叶与土壤碳氮变化研究

通过对西双版纳原始林、次生林和橡胶林土壤和凋落叶碳氮含量及碳氮比值间的变化特征研究,探讨林型变化下生态系统中生物化学计量比值的分异规律。研究结果表明:样品中土壤和凋落物氮对C/N值的影响要高于碳。西双版纳土地利用类型决定了土壤和凋落叶的碳氮含量,原始林SOC含量最高,橡胶林初产期(10 a)最低,而STN含量总体上橡胶林要高于原始林和次生林,不同树龄橡胶林土壤氮含量随林龄增加和割胶的进行发生了流失。不同林型间土壤有机碳(SOC)、全氮(STN)和凋落物碳氮比(C/N)的差异性显著,而土壤碳氮比、凋落物碳氮含量与林型相关性较弱。SOC、STN含量与凋落叶碳氮含量具有一定的负相关关系,说明土壤碳氮主要来自凋落物分解后养分的循环过程。     

转基因玉米转化体特异性PCR检测技术研究

根据不同转基因玉米中重组DNA结构,分别对转基因玉米Bt11、Bt176、Mon810、Mon863、TC1507、GA21和NK603设计转化体特异性引物进行PCR检测。在此基础上分别以玉米内参照基因(ZSSIIb)作对照,对Bt11、Mon810、TC1507和GA21、NK603、Bt176分别作两对四重PCR反应,实现在同一个PCR反应管中同时对3种转基因玉米及内参照基因的特异性检测。     

转基因棉子壳中Bt蛋白含量测定方法研究

应用农大试剂盒测定三种转基因棉子仁中 Bt蛋白的含量。以这三种转基因棉子仁为标准参考物 ,确定了 Agdia试剂盒测定棉子仁中 Bt蛋白的回归方程和线性范围。确定了该试剂盒测定棉子壳中 Bt蛋白的线性关系。测定了棉子壳中 Bt蛋白含量 ,中棉所 42、99B、33B棉子壳中 Bt蛋白含量平均值分别为 5 8.6、 6.8、 4.4ng· g-1。     

海南岛东南沿海地区不同森林类型林地凋落物现存量和养分特征

为揭示热带沿海地区不同森林类型凋落物现存量及其养分元素储存能力的差异,选取林地相邻、生境条件基本一致的青皮林和木麻黄林为研究对象,设置随机样地,采集未分解层、半分解层、已分解层凋落物样品,测定凋落物层现存量和主要养分元素含量、储量及其释放率。结果表明：（1）木麻黄林凋落物层现存量为29.49 t/hm²,是青皮林的2倍,2种林型不同分解层表现为：已分解层>半分解层>未分解层;（2）2种林型不同分解层养分元素含量基本遵循C>N>Mg>K>P的变化模式,随着凋落物分解,青皮林各养分元素含量逐级降低,木麻黄林则因养分元素不同而异,可能因凋落物C含量流失过多出现损失速率大于分解释放养分速率而造成半分解层N、P、Mg的含量相对增加,但均在已分解层含量最低;（3）木麻黄林凋落物层养分储量值为8448.23 kg/hm²,是青皮林的2倍,各分解层凋落物养分元素的储量依次为C>N>Mg>K>P,与养分元素含量变化规律一致,而养分释放率从未分解层（-1.79%、-0.97%）到半分解层（0.65%、1.23%）呈现增加趋势。总之,同一立地条件下,不同林型的凋落物现存量、养分含量及其储量的差异可能与植物叶片生物学特征、微环境条件、微生物种群及活性不同有关。     

转Bt基因玉米的生殖毒性评价

将昆明种小鼠按照体重随机分为5组(分别为高、中、低剂量组、阳性对照组和正常对照组),进行显性致死试验和精子畸形试验,评价转Bt基因玉米的生殖毒性。结果显示,饲喂转基因玉米的3组小鼠各项指标间的差异不显著(P0.05),与正常对照组相比亦无显著差别(P0.05),与阳性对照组差别显著(P0.05)。说明使用添加不同剂量转Bt基因玉米的饲料饲喂小鼠不会造成对雄性小鼠的生殖毒性。     

基因枪介导法获得转BtCry1Ac基因抗虫玉米植株的研究

利用基因枪介导法将含有Cry1Ac基因的质粒转入玉米愈伤组织,获得转Bt基因玉米植株,对所获得的转基因植株进行PCR分析和金标免疫试纸鉴定。结果表明,部分转化植株呈阳性,说明目的基因已经整合到玉米基因组中。将转基因植株自交获得T1代种子,对T1代植株进行田间抗虫鉴定,结果表明,与对照相比转基因玉米植株的抗虫活性明显强于非转基因植株。     

分子改造Cry蛋白基因的转基因玉米创制及其抗虫功能评价

利用结构域交换和密码子优化方法对苏云金芽孢杆菌(Bt)杀虫晶体蛋白Cry1Ab进行合理化设计改造,获得新型Bt蛋白编码基因cry FLIa。利用农杆菌介导法将该基因转入玉米Hi II中,对转基因后代开展分子鉴定和抗性评价等相关工作。结果表明,cryFLIa基因已整合进玉米基因组中,连续3代自交材料检测显示,转基因玉米目标基因正常表达并稳定遗传;蛋白在植株叶片中发育各时期的表达各异,在灌浆期蛋白表达量较高(471.883 ng/g)。室内生测和田间人工接虫试验表明,转cryFLIa基因玉米具有抗亚洲玉米螟的能力。     

转基因抗虫玉米对亚洲玉米螟的抗性评价

采用田间人工接虫鉴定方法,根据玉米抗螟性田间鉴定评价标准,研究转基因玉米Bt799和NC6304YGRR对亚洲玉米螟的抗性.心叶期接虫试验结果表明,以食叶级别作为评价参数,2种转基因玉米对亚洲玉米螟具有良好的抗性,食叶级别均为1级;2种非转基因玉米食叶级别均大于7级.吐丝期接虫试验结果表明,以单株虫孔数、单株活虫数、单株隧道个数及单株隧道长度作为评价参数,2种转基因玉米对亚洲玉米螟抗性均显著高于各自对应的非转基因玉米.转基因抗虫玉米Bt799和NC6304YGRR田间抗虫效果良好,均能保护玉米在整个生育期内不受亚洲玉米螟危害.     

玉米株高主效QTL qPH2.4的定位分析

课题组前期以玉米自交系郑58为轮回亲本,以昌7-2为供体亲本,通过分子标记辅助选择获得染色体单片段代换系Z12和W16。Z12和W16在bin2.07区域均含有1个来源于昌7-2的染色体片段,株高均显著高于轮回亲本郑58。利用郑58和Z12为材料构建F2分离群体,基于重测序和混合分离分析(BSA)策略,将株高主效QTL qPH2.4定位于第2染色体13.95 Mb(201 457 953~215 022 157 bp)的区域内。利用在目标区间内筛选出的20对多态性分子标记对包含743个单株的郑58×Z12 F2分离群体和包含1 720个单株的郑58×W16 F2分离群体进行基因型分析,结合田间株高数据进行QTL定位,将株高主效QTL qPH2.4定位在InDel分子标记ph-18和ph-19之间,区间的遗传距离为0.57 cM,物理距离为626 kb。参考B73基因组(RefGen_v4)注释信息,该区间内存在17个注释基因,其中,包含可以调控油菜素内酯信号的基因Zm00001d006677。     

Interacting effects of yak dung deposition and litter quality on litter mass loss and nitrogen dynamics in Tibetan alpine grassland

The effects of grazing‐induced dung deposition on plant growth and soil attributes are well established, but little is known about dung effects on litter decomposition. Here, we tested effects of yak dung on litter decomposition and nutrient content in a Tibetan alpine meadow. We incubated litter of four common alpine meadow species using litter bags in the field. Two low‐quality species (Kobresia capillifolia and Elymus nutans) with low nitrogen (N), high C/N and Lignin/N, and two high‐quality species, (Saussurea nigrescens and Thermopsis lanceolata) were incubated in monoculture with and without dung addition. Mass loss of leaf litter, fibre fraction (cellulose, hemi‐cellulose and lignin), N and phosphorus (P) were measured after 6, 12 and 18 months of incubation in the field. Dung addition significantly increased decomposition constants for low‐quality litter species, but not for high‐quality litter species. Dung addition promoted cellulose and hemi‐cellulose loss, but lignin loss was not affected by dung addition, except after 12 months for high‐quality litter species. Dung reduced N immobilization after 6 months and did not affect subsequent release in low‐quality litter species, and promoted N release after 6 and 12 months in high‐quality litter species. Regardless of litter quality, dung increased P release after 6 and 12 months. Our results suggest grazing‐induced dung deposition may accelerate C and nutrient turnover, primarily through increasing the mass loss of low‐quality litter, P release from litter and N release from high‐quality litter. The mechanisms underlying the effects of dung deposition need to be clarified in future studies.     

Individual and combined effects of salinity and waterlogging on Cry1Ac expression and insecticidal efficacy of Bt cotton

Salinity, waterlogging and a combination of both stresses are severe threats to plant growth, development and yield of field-grown cotton (Gossypium hirsutum L.), but their individual or combined effects on insecticidal efficacy of Bacillus thuringiensis (Bt) transgenic cotton and the underlying mechanisms are not well understood. In the present study, two cotton cultivars (33B and SCRC17) containing the Cry1Ac insecticidal protein gene were planted in 10 L pots filled with soil and allowed to grow in a greenhouse. The potted plants were either treated with NaCl (5 mg/g, w/w), waterlogging, or a combination of both stresses at the three true-leaf stage, and levels of total soluble protein, Bt insecticidal protein, gossypol and the control efficacy as indicated by mortality of bollworm larvae were examined at 7-day intervals after stress. Waterlogging and a combination of salinity and waterlogging reduced total protein content by 40–46% and 45–65% and Bt protein content by 38–50% and 45–72% from 7 to 21 days after stress, relative to the non-stressed control, respectively. The control efficacy was significantly reduced by either waterlogging or the combined stress. Regression analysis indicated that Bt protein content was correlated to total soluble protein content (R² = 0.7677*), while Bt cotton efficacy was correlated to Bt protein level (R² = 0.7917**). Salinity reduced Bt protein by 11–22% and total soluble protein by 5.7–7.2% from 7 to 21 days after NaCl stress, but did not result in reduction in control efficacy. It is concluded that reduced bollworm control efficacy under waterlogging or the combined stress could be mainly attributed to the declined levels of Bt protein, which is closely associated with the inhibited nitrogen metabolism by stresses. As one of the secondary compounds that are toxic to pests, increases in gossypol may be involved in maintaining the efficacy when Bt protein level was reduced under salinity.     

玉米抗病相关基因ZmEDS1的克隆及表达分析

从玉米中克隆ZmEDS1基因的cDNA序列,全长2 164 bp,开放阅读框(Open reading frame,ORF)长1 860 bp,编码619个氨基酸。生物信息学分析表明,该基因编码的蛋白等电点为6.05,分子量为68.74 kDa,内部无信号肽结构,N端有一个酯酶结构域。系统进化树分析表明,玉米ZmEDS1蛋白和高粱EDS1L蛋白的亲缘关系最近,同源性高达94%。采用实时荧光定量PCR分析病毒侵染下该基因在感性材料郑58和抗性材料D863F中的表达模式,在两种材料中,ZmEDS1基因均在病毒侵染48 h的表达量最高,分别达到0 h对照组感、抗材料的1.56、3.47倍,在抗病材料D863F中的表达水平高于感病材料郑58。初步判断,ZmEDS1基因应答病毒的侵染过程,且在感病材料和抗病材料中的响应模式存在差异。     

Leaf litter decomposition and diversity of arthropod decomposers in tropical <Emphasis Type="Italic">Muyong</Emphasis> forest in Banaue,Philippines

The Muyong forest, an indigenous secondary forest in Banaue, Ifugao, Philippines, plays a crucial role in the Muyong–Payoh system, a continuum of secondary forest and rice terrace, of the Banaue rice terraces by providing water and nutrients to the rice plants in the Payoh terraces. In recent decades, the planting of introduced tree species in the Muyong forest has threatened the sustainable provision of ecosystem services such as water balance and nutrient cycling. To further understand nutrient cycling in the Muyong–Payoh systems, this study was conducted in Poitan, Banaue, Ifugao to gather preliminary baseline data on floral diversity, leaf litterfall rate, leaf litter decomposition rate, and diversity and succession of arthropods in decomposing leaf litter in a Muyong forest. Vegetation analysis was done by identifying and describing the trees growing inside the five 10 m × 10 m quadrat sampling plots. Monthly leaf litter fall was collected in 1 m × 1 m litter traps, and the dry weight was determined after oven-drying at 65 °C for 48 h. Leaf litter decomposition experiment was established by laying out 12 nylon mesh bags containing fresh leaf litter in each of the four sites on the forest floor and one bag was retrieved every month to determine the change in dry weight of the leaf litter. Six bulk soil samples were collected from the Muyong forest floor and analyzed for organic matter, pH, available P and exchangeable K. Fresh leaf litter samples were analyzed for total N, P and K contents. Arthropods in the collected decomposing leaf litter were extracted using Berlese funnel and later identified up to families level using arthropod taxonomic key. The diversity of plants in the Muyong forest includes thirty-eight tree species belonging to 19 families dominated by indigenous tree species. Results showed that the monthly leaf litter fall was higher during the dry months of March to May and lower during the wet months. The estimated total leaf litter fall in Muyong forest was comparable to published litter fall from tropical secondary forests. The N, P and K contents of fresh leaf litter range from 1.0 to 1.2, 0.11 and 0.40%, respectively. The first month of decomposition has the fastest rate while the decomposition rate during the next 4 months ranged from 0.125 to 0.251. Complete decomposition or mass lost in the leaf litter in the Muyong forest took place within 5 months. The soil arthropods identified in the decomposing leaf litter were composed of 13 orders and 28 families. Majority of the collected arthropods were insects while other species including mites, spiders, millipedes and sowbugs were also present. Detrivore and fungivore Families were found to be dominant in the decomposing leaf litter. Moreover, the composition and succession of arthropod decomposer community varied in the three sampling methods and with the changing quality of the litter material as decomposition progressed. The wide diversity and succession of leaf litter decomposers consisting of detritivores, predators, fungivore and herbivore coupled with abundant rainfall and warm temperature are the two main factors that contribute to the fast rate of leaf litter decomposition and nutrient turn over in the Muyong forest. Thus, the Muyong forest can sustain the productivity of rice planted in the adjoining downstream Payoh terraces. Hence, the conservation and management of the Muyong forest is critical in maintaining the ecological functions of the Muyong–Payoh continuum.     

Metal uptake by tall fescue (Festuca arundinacea) as affected by poultry litter application

Poultry litter is commonly applied to pastures as an organic fertilizer. However, poultry litter also typically contains numerous heavy metals that may accumulate in soil and can pose an environmental threat when it is applied to pastures. The objective was to ascertain uptake characteristics of heavy metals by tall fescue (Festuca arundinacea Schreb.) from soil with a history of poultry litter additions as affected by subsequent applications of poultry litter. Poultry litter was applied to small plots at rates of 0, 2·2 and 4·5 t dry litter ha^?1. In the 7·5 months following application of litter, cumulative dry‐matter (DM) production of herbage was higher (P < 0·05) in the plots that received poultry litter compared with the control plots where no litter was applied. However, concentrations of Al, Cu, Fe, Mg, Mn, Se and Zn in herbage were unaffected by the rate of application of poultry litter. All metal tissue concentrations, except for Fe, were affected by sampling date. While tall fescue responds to poultry litter with increased DM production, it does not appear to accumulate excessive quantities of micronutrients associated with the application of poultry litter.     

Above and belowground litter decomposition of cover crops grazed at different intensities

Grazing cover crops may increase land-use efficiency while promoting sustainability. We investigated how grazing intensity affects cover crop litter quantity, quality, decomposition, and cotton (Gossypium hirsutum L.) N uptake. Cover crops were a mixture of rye (Secale cereale L.) and oat (Avena sativa L.) managed as follows: no grazing +34 kg N ha⁻¹ (NG34), no grazing +90 kg N ha⁻¹ (NG90), heavy grazing (HG), moderate grazing (MG), and light grazing (LG). Grazed treatments received 90 kg N ha⁻¹. After cover crop termination, above- and belowground litter was collected and incubated in situ for 0, 4, 8, 16, 32, 64, and 128 days, with cotton plants sampled on the same days to estimate N recovery and synchrony between N release from litter and uptake by cotton. By Day 128, only 13% of initial NG34 aboveground biomass had disappeared, whereas 42% of HG disappeared. Nitrogen retained in aboveground litter of HG was less than NG90 (27 vs. 60 kg N ha⁻¹), and aboveground final N stock (at Day 128) of HG was less than NG90 and LG (16, 47, and 41 kg N ha⁻¹, respectively). Belowground litter contributed 98 kg N ha⁻¹ versus 46 for aboveground. Belowground N disappearance from litter bags was greater from NG90 than NG34 (39 vs. 21 kg N ha⁻¹). Cotton N uptake by Day 128 was similar across treatments (191 kg N ha⁻¹). Grazing cover crops impact aboveground litter quantity, quality, and decomposition rates, and belowground litter plays an important role on the N cycling.     

Litter dynamics of Dactylis glomerata and Vicia villosa with respect to climatic and soil characteristics

The rates of litter decomposition, organic matter loss and nutrient release for Dactylis glomerata (Gramineae) and Vicia villosa (Leguminosae) were studied at two sites in north Greece, which differed in soil pH, soil particle distribution and nutrient availability.
Climate, soil characteristics and taxonomic plant differences affected the rates of litter decomposition. Litter loss was higher at site A (neutral soil) than at site B (acid soil). Organic matter loss was generally low. Dry weather affected both parameters. Nitrogen release from litter was higher for both species at site A. The rate of P and K release was higher in the neutral soil than in the acid soil for both species, while that of Ca for both species and of Mg for Vicia was higher in the acid soil. Phosphorus, Ca and Na release from the litter of the leguminous species began earlier than from the graminaceous species. P mineralization from Vicia litter seemed to start just after its incorporation into the soil.     

Impacts of transgenic Bt cotton on a non-target pest, Apolygus lucorum (Meyer-Dür) (Hemiptera: Miridae), in northern China

Transgenic Bt (Bacillus thuringiensis) cotton has been effectively used to control the cotton bollworm, Helicoverpa armigera (Hübner) in China. However, in recent years, following the wide commercialization of Bt cotton in northern China there have been frequent outbreaks of the non-target pest Apolygus lucorum (Meyer-Dür). To clarify how transgenic cotton contributes to these outbreaks, a four-year field investigation of population dynamics and laboratory life table studies were carried out from 2007 to 2010 to evaluate the impact of two transgenic cotton cultivars (SGK321 expressing Cry1Ac + CpTI and GK12 expressing Cry1Ac) and their corresponding parental non-transgenic lines (Shiyuan321 and Simian3) on A. lucorum. There were no significant differences in the population densities of A. lucorum found in Bt cotton and non-Bt cotton plots, whether one compared those that had received insecticide treatments or those that had not. However, population densities of A. lucorum were significantly lower in pesticide treated plots than in controls. Furthermore, there were no significant differences in the net reproductive rates, generation times or intrinsic rates of increase of A. lucorum when reared on either Bt or non-Bt cotton cultivars. These results suggest that Bt cotton has no direct positive or negative effects on the biology of A. lucorum, so the most logical explanation for the observed outbreaks is the decrease in pesticide applications following the commercial release of Bt cotton.