澄黄滨珊瑚和丛生盔型珊瑚非培养放线菌多样性

【目的】研究澄黄滨珊瑚(Porites lutea)和丛生盔型珊瑚(Galaxea fascicularis)联合放线菌物种多样性。【方法】实验提取两种珊瑚的总DNA,利用放线菌特异性引物对样品总DNA进行扩增,通过构建16S rRNA基因克隆文库和系统发育分析,对三亚鹿回头岸礁区优势物种澄黄滨珊瑚和丛生盔型珊瑚联合放线菌的多样性和群落结构进行研究。【结果】118个从澄黄滨珊瑚克隆文库中随机挑选的阳性克隆子归为58个OTUs,主要分布于酸微菌亚目、棒状杆菌亚目、微球菌亚目、丙酸杆菌亚目和未知类群。丛生盔型珊瑚克隆文库共获得96个序列,归为31个OTUs,主要分布于酸微菌亚目和未知的放线菌类群。多样性指数和稀疏度曲线分析结果显示澄黄滨珊瑚联合放线菌物种多样性比丛生盔型珊瑚更高。【结论】澄黄滨珊瑚和丛生盔型珊瑚拥有较高水平的放线菌物种多样性和复杂的群落结构,并隐藏着大量的高等级放线菌新分类单元。     

鹿回头多孔鹿角珊瑚与丛生盔形珊瑚性腺组织学研究

造礁石珊瑚繁殖生物学是开展珊瑚有性修复技术的基础, 对珊瑚礁生态系统修复具有重要的指导意义。本研究选取三亚鹿回头多孔鹿角珊瑚(Acropora millepora)与丛生盔形珊瑚(Galaxea fascicularis)作为研究对象, 观察它们性腺特征, 明确多孔鹿角珊瑚与丛生盔形珊瑚有性繁殖类型。结果表明: (1) 多孔鹿角珊瑚是雌雄同体产卵型珊瑚, 丛生盔形珊瑚是假雌全异株产卵型珊瑚; (2) 多孔鹿角珊瑚和丛生盔形珊瑚的虫黄藻都由后天获取; (3)多孔鹿角珊瑚在其卵母细胞和精母细胞发育到Ⅳ时相后, 卵巢与精巢之间肠表皮消失, 并在随后的5 d 左右产卵; 丛生盔形珊瑚在其卵母细胞发育到Ⅲ时相后的20 d 左右产卵。本研究结果, 为三亚海域造礁石珊瑚繁殖生物学的深入研究提供基础数据支持。     

光对马卡愈伤组织生长、丛生芽诱导和存活的影响

马卡属于十字花科独行菜属,具有极高的营养价值和药用价值。在快繁过程中,光对马卡愈伤组织生长,丛生芽的诱导和存活有显著的影响。绿光和蓝光既不利于愈伤组织的生长也不利于丛生芽的诱导和存活。白光、红光和黄光能明显促进愈伤组织的生长,在这些光照条件下丛生芽的诱导率为60%～80%,丛生芽存活率为29%～36%。适当延长光照时间可提高丛生芽的存活率,合适的光照时间为16h/d。但是过强的光照可使丛生芽的存活率降低,合适的光照强度为24～41μmol/m2.s。     

麻疯树种子发育过程中JcOle14.3和JcOle16.6基因的表达模式研究

油质蛋白基因对种子中油体的形成至关重要,该研究通过实时荧光定量PCR,对麻疯树的两个油质蛋白基因JcOle14.3和JcOle16.6在种子不同发育时期的表达模式进行了分析。结果表明:两个基因在种子发育初期(10~30 d)表达量逐渐升高,但表达水平均较低;40 d时表达量急剧增加并达到最高,而种子发育后期(50~55 d)两个基因表达水平均逐渐降低。由此可初步推测,JcOle14.3和JcOle16.6基因的表达量可能与种子油脂积累量存在正相关。该研究结果为麻疯树油体形成机理和油质蛋白的深入研究提供了理论基础。     

广西金钟山细叶云南松径向生长及其对气候因子的响应

为探究广西金钟山细叶云南松径向生长及其对气候的响应,该文建立了细叶云南松树木年轮标准年表,采用响应分析探讨了径向生长与气候因子的关系,并使用逐步回归和方差分解量化了不同气候因子对径向生长的影响。结果表明:(1)响应分析结果显示,上一年1月、8月、9月、11月的日照时数以及上一年10月的平均最低气温和平均气温与标准年表年轮宽度均呈显著正相关,而上一年6月降雨量>10 mm的天数与年轮宽度呈显著负相关; 当年2月的降雨量、3月的空气相对湿度和平均最低气温、6月的日照时数以及9月的平均气温和平均最高气温均与年轮宽度呈显著正相关。(2)逐步回归最终模型的方差分解结果显示,上一年10月的平均最低气温对细叶云南松径向生长的影响最大(方差解释量达23.35%),其次是当年9月的平均最高气温(方差解释量为10.39%); 上一年1月和11月的日照时数分别解释了径向生长变异的3.94%和6.58%。综上表明,秋季的温度和冬季的光照条件是限制细叶云南松径向生长最主要的气候因子,早春干旱和雨季大降雨量会降低细叶云南松的径向生长。     

土壤灭菌处理对入侵植物南美蟛蜞菊及其伴生种生长的影响

该研究以温室盆栽法对南美蟛蜞菊重度入侵土壤进行高温高压湿热灭菌、添加杀真菌剂灭菌和添加杀细菌剂灭菌的处理后,将三种植株定植96 d后测定各生理指标参数,研究重度入侵土壤中各微生物类群对南美蟛蜞菊及其伴生种金腰箭和狗肝菜生长的影响。结果表明:在杀真菌、杀细菌以及高温高压湿热灭菌和未处理的南美蟛蜞菊重度入侵土壤中,三种植物生长情况均存在较大差异。在高温高压湿热灭菌土壤中南美蟛蜞菊的生长受到显著抑制,与未处理土壤中的生长情况相比,株高降低了17.59%,叶片数降低了38.10%,生物量降低了56.00%,电子传递速率变化不明显。在杀真菌土壤和杀细菌土壤中金腰箭的生长也受到显著抑制,与未处理土壤中的生长情况相比较,杀真菌土壤中的金腰箭株高降低最多(为42.28%),叶片数降低了38.89%,生物量降低了16.99%,电子传递速率变化不明显;在杀细菌土壤中金腰箭株高降低了36.64%,叶片数降低最多(为38.89%),生物量降低了33.67%,电子传递速率升高了11.11%。由此可见,不含微生物的土壤对南美蟛蜞菊生长有较强的抑制作用,不含真菌和细菌的土壤对金腰箭的生长有明显抑制作用。南美蟛蜞菊重度入侵土壤不仅适合南美蟛蜞菊的生长,也适合金腰箭的生长,对狗肝菜影响不大。     

煤粉尘沉降对鄂尔多斯高原优势植物羊柴幼苗生长的影响

随着鄂尔多斯煤矿开采的日益加剧,开采和运输过程中产生的煤粉尘沉降已成为影响当地植物生长的一个重要影响因子。通过近自然生境条件下的控制实验,以鄂尔多斯高原优势植物羊柴(Hedysarum laeve)为研究对象,探究不同梯度煤粉尘沉降量(0—3.5 mg/cm2)对其幼苗的光合生理特性和生长的影响。研究结果表明,随着煤粉尘沉降量的增加,羊柴叶片的气孔导度(Gs)、胞间二氧化碳浓度(Ci)、叶片水分饱和水汽压亏缺(Vpdl)等因子发生了不同程度的改变,导致净光合速率(Pn)和蒸腾速率(Tr)降低,使得幼苗的植株高度、叶片数、地上和地下生物量降低。因而,积累到一定程度的煤粉尘颗粒通过影响叶片气孔的水汽交换过程和降低叶片表面的光照强度,影响了叶片的光合生理过程,从而抑制了羊柴幼苗的生长。     

Germination of cocklebur seed and growth of their axial and cotyledonary tissues in response to C2H4, CO2 and/or O2 under water stress

Abstract. Germination modes of lower seeds of cocklebur (Xanthium pennsylvanicum Wallr.) under different water stresses, prepared with mannitol solution, were examined in relation to gaseous factors. As the concentration of mannitol increased, germination was increasingly inhibited at a mode which was drawn by two straight lines having different slopes and meeting at an angle. One is a sharp line occurring at the lower concentrations of mannitol; the other is a gentle line occurring at higher concentrations of mannitol. The former reflected the growth response of axial tissues to mild water stress, whereas the latter reflected the growth response of cotyledonary tissues to severe water stress. The germination potential of cocklebur seeds increased with increasing temperature. Thus, the seeds were more resistant to water stress at higher than al lower temperatures. This increased germination potential under water stress resulted from the greater growth potential of axial tissues, but not cotyledonary tissues, at higher temperature. Increased O₂ levels improved both the reduced axial and cotyledonary growth under water stress. Carbon dioxide predominantly enhanced axial growth under water stress, whereas C₂H₄ exclusively enhanced cotyledonary growth. Thus, these gases were effective in potentiating germination under water stress. When combined with each other, these gases caused more pronounced growth of the axial and cotyledonary tissues, leading to germination under more severe water stresses. Maximal axial and cotyledonary growth under water stress occurred in the simultaneous presence of CO₂, C₂H₄ and O₂, which allowed the germination at higher mannitol concentrations above 0.6 kmol m^?3 From these results, it was suggested that cocklebur seeds would override water stress by depending upon both the Corresponding axial growth and the C₂H₄-responding cotyledonary growth.     

Effect and interaction of temperature and photoperiod on growth and partitioning in three groundnut (Arachis hypogaea L.) genotypes1

Effect of temperature and photoperiod and their interaction on plant growth and partitioning of dry matter to pods was examined in three selected groundnut genotypes viz., TMV 2, NC Ac 17090 and VA 81B. The genotypes were grown in six walk-in growth chambers which were programmed to simulate three temperature regimes (22/18°C, 26/22°C and 30/26°C day/night) each under long (12 h) and short (9 h) photoperiods. The plant growth rates and partitioning of dry matter to pods were estimated on a thermal time basis. Plant growth rate (PLGR) was significantly influenced by temperature, photoperiod and genotype, whereas pod growth rate (PDGR) was influenced primarily by temperature and genotype. The interaction of genotype with photoperiod and with temperature was significant for both PLGR and PDGR. For example, at the 22/18°C temperature regime, VA 81B had a high PDGR, while NC Ac 17090 did not even initiate pod growth. The partitioning of dry matter to pods (Pf) was also significantly influenced by photoperiod, temperature and genotype, and significant interactions were found. Photoperiod did not significantly affect Pf under the low temperature regime, but at higher temperatures, partitioning to pods was significantly greater under short days. Pf of VA 81B was relatively insensitive to photoperiod compared with the other two genotypes. The study provided evidence of genotypic variability for photoperiod × temperature interactions which could influence adaptation of groundnut genotypes to new environments.     

玉米转录因子WRKY76克隆及抗纹枯病表达模式分析

玉米纹枯病是影响玉米产量和品质的重要病害之一。转录因子WRKY家族部分成员能够调控水杨酸和茉莉酸甲酯信号传递方式来激发防卫反应基因的表达。在NCBI上检索玉米中WRKY家族成员及拟南芥中抗病相关的WRKY家族成员,利用CLUSTAL X和MEGA5.05构建系统进化树,发现转录因子WRKY76可能参与玉米抗纹枯病的调控途径。该研究以玉米抗纹枯病材料R15和感病材料Ye478为对象,在玉米拔节期接种立枯丝核菌AG1-IA,首先分别于接菌前(对照)和接菌后1、2、4、6、12、24 h取叶鞘;然后分别进行水杨酸和茉莉酸甲酯胁迫处理,分别于处理前(对照)和处理后1、2、4、6、12 h取叶鞘,提取RNA,实时荧光定量PCR分析WRKY76转录因子基因在玉米叶鞘组织中不同胁迫条件下的差异表达。结果表明:在立枯丝核菌AG1-IA胁迫下,WRKY76转录因子基因在胁迫后1 h表达量达最大值,抗病材料R15的相对表达量高于感病材料Ye478且差异显著(P≤0.05);经水杨酸(Salicylic Acid,SA)处理,WRKY76在抗感材料中表达趋势相似,在感病材料掖478中,WRKY76被诱导而显著地上调表达,在抗病材料中,相对表达量峰值出现在胁迫后4 h,且相对表达量低于感病材料掖478。经茉莉酸甲酯(Methyl jasmine,Me JA)处理,WRKY76基因在感病材料中呈现下调表达趋势。WRKY76基因在1 h表达量为对照的0.6倍,其他调查时间点基本都在0.1~0.3之间。在抗病材料R15中,WRKY76基因表达呈现上升趋势,变化趋势不明显。这表明WRKY76转录因子基因能够被病原物、SA、Me JA诱导表达,可能参与植物抗纹枯病调控途径。     

新疆阿勒泰地区8种生态型罗布麻光合生理及生长特性研究

为明确新疆阿勒泰地区不同生态型罗布麻生物学性状的稳定性和差异性,以8种生态型罗布麻为材料,对其外部形态、光合生理特征及生长特性(株高、分枝数、地径和叶干重等)进行评价。结果表明:(1)除白麻宽叶外,其余生态型罗布麻在移栽3年后株型、叶型、叶色和花色等形态特征均保持稳定。(2)8种生态型的光合生理特征在不同生长时期和不同时间段存在差异;各生态型罗布麻均存在光合"午休"现象,Pn在上午时最高(17.8~30.1μmol·m-2·s-1),中午时较上午降低6%~45%,并以白麻紫斑和大叶白麻降幅最大,白麻白花降幅最小。(3)多数生态型的Pn、Tr和Ci/Ca值与Gs的变化特征具有较好的一致性,说明光合和蒸腾"午休"主要受气孔因素影响,但白麻粉秆的光合"午休"与之不同,受非气孔因素的影响较明显。(4)相对而言,大叶白麻、白麻青秆、白麻红秆、白麻粉秆生态型为低蒸腾高光合高水分利用效率型,罗布红麻为低蒸腾低光合高水分利用效率型,白麻白花为低水分利用效率型且在上午表现为低蒸腾低光合型,而在中午和下午表现为高蒸腾高光合型,白麻紫斑则与白麻白花相反。(5)白麻粉秆和白麻白花的株高(110cm)、地径(8.2mm)、单株叶干重(22.6g)均较高;大叶白麻的茎节最长(6.5cm)。可见,多数生态型罗布麻在长期进化中形成适应其生长环境的稳定性状;白麻白花较其他生态型具有更好的耐受高光强、高温和对弱光利用的能力,而白麻紫斑、大叶白麻和白麻粉秆的这种能力较差;罗布红麻和白麻白花可作为产叶型,白麻红秆和白麻粉秆可作为产叶及产纤维型进行培育,而大叶白麻不适合在北疆种植。     

The transposable elements resident on the plasmids of Pseudomonas putida strain H, Tn 5501 and Tn 5502 , are cryptic transposons of the Tn 3 family

Genes for (methyl)phenol degradation in Pseudomonas putida strain H (phl genes) are located on the plasmid pPGH1. Adjacent to the phl catabolic operon we identified a cryptic transposon, Tn5501, of the Tn3 family (class II transposons). The genes encoding the resolvase and the transposase are transcribed in the same direction, as is common for the Tn501 subfamily. The enzymes encoded by Tn5501, however, show only the overall homology characteristic for resolvases/integrases and transposases of Tn3-type transposons. Therefore it is likely that Tn5501 is not a member of one of the previously defined subfamilies. Inactivation of the conditional lethal sacB gene was used to detect transposition of Tn5501. While screening for transposition events we found another transposon integrated into sacB in one of the sucrose-resistant survivors. This element, Tn5502, is a composite transposon consisting of Tn5501 and an additional DNA fragment. It is flanked by inverted repeats identical to those of Tn5501 and the additional fragment is separated from the Tn5501 portion by an internal repeat (identical to the left terminal repeat). Transposition of phenol degradation genes could not be detected. Analysis of sequence data revealed that the phl genes are not located on a Tn5501-like transposon. Received: 21 July 1997 / Accepted: 7 July 1998     

不同养分环境下邻株竞争对木荷和杉木生长、细根形态及分布的影响

以木荷和杉木为试验材料,模拟异质和同质两种森林土壤养分环境,设计单植、两株纯植和两株混植3种栽植方式,开展盆栽试验研究木荷与杉木混交造林增产及木荷生长竞争优势形成的原因.结果表明: 与同质养分环境相比,异质养分环境中木荷与杉木混植时两树种均具有较高的苗高和干物质积累量,且木荷竞争优势明显,这与其根系可塑性强有关.混植的木荷各径级细根大量增生,其根系总长度、表面积和体积比杉木高80%～180%.木荷细根在垂直方向上采用了补偿性的生长策略,即除占据富养表层外,还在低养分斑块中大量增殖以获得更大的竞争优势.木荷与杉木的细根在土壤中的拓殖深度不同,生态位分化,缓解了两树种根系对养分的强烈竞争,提高了混植产量.纯植的木荷由于根系自我识别作用,抑制了根系的生长,使得纯植产量较低.细根在空间上错开和均匀分布可能是木荷纯林结构稳定的原因之一.建议在生产中采用块状整地和表层施肥等措施,改善土壤养分分布状况,营建混交林促进木荷和杉木生长,而对已营造的木荷人工纯林,可以及时调控林分密度促进林木生长.