径向谐和激励下圆形隧道衬砌的动力稳定性

对径向谐和激励下圆形隧道的动力稳定性进行了研究，从动荷载下衬砌结构的振动方程出发，得到了隧道衬砌动力失稳临界频率计算公式，对可能影响隧道衬砌动力稳定性的因素进行了参数分析，探讨了系统参数，如地基土的性质、衬砌径厚比、外激励的性质以及系统的阻尼对衬砌动力稳定性的影响，计算结果表明：隧道周围土体的性质以及系统阻尼对衬砌的动力稳定性影响不大；相反，衬砌的厚度和外激励特性对衬砌的动力不稳定区域影响较大     

Detecting interactive effects of N fertilization and heat stress on maize productivity by remote sensing techniques

The objective of this study was to compare the performance of two different remotely sensed techniques in detecting the effects of terminal heat stress and N fertilization on final maize aerial biomass (AB) and grain yield (GY). The study was conducted under field conditions for two consecutive growing seasons. Six N treatments combining three doses [0, 100, 200 Kg N ha⁻¹] and two timings [at V4 and at 15 days before silking] were applied. Within each N treatment three heat treatments were applied (pre-flowering, post-flowering and the control treatment at ambient air temperature). Remote sensing measurements were taken with a multispectral band camera to measure the normalized difference vegetation index (NDVI) and a digital Red/Green/Blue (RGB) camera to measure the normalized green red difference index (NGRDI). Both indices failed to predict the GY of pre-flowering heat-treated plants due to grain set establishment problems that could not be detected by vegetation indices which are designed to capture differences in green canopy area. In contrast, both the NGRDI and the NDVI correlated positively with GY and AB in the control heat treatment and to a lesser extent in the post-flowering heat treatment. Under the control heat treatment, the NGRDI exhibited higher correlations with AB and GY than the NDVI across the N fertilization treatments. Since the NGRDI is formulated based only on the reflectance in the visible regions (VIS) of the spectrum (Green and Red) without dependence on the near infrared regions (NIR), it performs better than the NDVI. This is because it overcame the reported saturation patterns at high leaf area index and was more efficient at capturing even small differences in leaf colour (chlorophyll content) due to the different applied N treatments. Also, the NGRDI seemed to be a more seasonally independent parameter than the NDVI, which is more affected by temporal variability within the field, and thus the NGRDI predicted AB and GY better than the NDVI when combining the data of the two growing seasons.     

芹菜水孔蛋白基因AgPIP2;1的克隆及其对非生物胁迫的响应

为了研究芹菜质膜内在蛋白基因的序列特征及其在非生物胁迫条件下的表达特性,探讨其抗逆功能,以芹菜品种六合黄心芹为试验材料,通过RT-PCR技术克隆AgPIP2;1基因,通过生物信息学软件分析其核苷酸和氨基酸序列特征,并采用荧光定量PCR技术检测其在不同组织的表达及其对非生物胁迫的响应。结果表明,AgPIP2;1基因含有1个861 bp的开放阅读框,编码286个氨基酸,其编码的蛋白属于PIP2类蛋白。氨基酸序列分析显示,AgPIP2;1含有高度保守的NPA基序以及高等植物PIP蛋白的保守序列,与其他物种PIP2类蛋白具有较高的同源性,与胡萝卜DcPIP2;1的氨基酸序列同源性达到97.90%。在亲缘关系上与大豆GmPIP2;1、胡萝卜DcPIP2;1和绿豆VrPIP2;1较为接近。实时荧光定量PCR技术分析表明,AgPIP2;1基因在芹菜根、叶柄和叶片中均有表达,其中在叶片中的表达量最高,在根中的表达量最低,呈现比较明显的组织特异性。此外,AgPIP2;1基因受到高温、低温、干旱和盐等非生物胁迫的诱导,说明该基因可能参与芹菜抵御非生物胁迫的过程。本研究为进一步了解AgPIP2;1基因的功能及其在非生物胁迫中的作用奠定了基础。     

转MsLEA4-4基因拟南芥株系的耐盐性分析

为了深入研究紫花苜蓿（Medicago sativa）MsLEA4-4基因的抗逆性，本试验对前期获得的转MsLEA4-4基因的拟南芥（Arabidopsis thaliana）株系进行不同浓度盐胁迫处理，以验证MsLEA4-4基因在拟南芥植株体内的耐盐性。试验结果表明：盐胁迫后转基因株系的发芽率达到55%，比对照植株（Control plant，CK）高81%；转基因株系的鲜重、叶绿素含量均高于CK（P<0.05）；盐胁迫后转基因株系的存活率比CK提高75.0%~81.3%；盐胁迫明显抑制根系生长，但转基因植株的侧根数量比CK多4~5根（P<0.05）；盐胁迫后转基因株系体内的可溶性糖含量（P<0.05）和超氧化物歧化酶（P<0.01），过氧化氢酶（P<0.01），过氧化物酶（P<0.05）活性均高于CK，脯氨酸（P<0.01）和丙二醛（P<0.05）含量均低于CK。综上可得，MsLEA4-4基因参与了拟南芥体内的耐盐性调控，提高了转基因拟南芥对盐胁迫的耐受性。本研究为进一步探索MsLEA4-4在转基因紫花苜蓿盐胁迫中的功能及培育耐盐性紫花苜蓿品种提供依据。     

玉米受精和早期子粒发育过程及逆境胁迫对其影响

玉米受精及子粒发育早期是决定穗粒数及粒重的重要时期,也是对环境变化相对较敏感的阶段。受精极核需要经历游离核、细胞化和细胞分化3个阶段形成胚乳,受精卵同样需要一系列的分裂分化形成最终的胚。玉米受精前极易遭受不良环境的影响,导致性器官发育不正常,影响花粉或花丝活力间接影响玉米受精过程。受精过程中的环境胁迫会通过阻碍花粉与花丝的识别、减缓花粉管在花丝中的延伸速率影响受精过程。子粒发育早期主要是受精极核分裂分化形成胚乳、受精卵分裂分化形成胚的过程,该阶段遭受环境胁迫下,胚乳细胞分裂受阻影响子粒库容。研究表明,逆境胁迫条件下,玉米的受精及子粒早期发育过程与碳水化合物的代谢以及激素的合成密切相关。     

Protective and defensive roles of non-glandular trichomes against multiple stresses:structure-function coordination

As superficial structures,non-glandular trichomes,protect plant organs against multiple biotic and abiotic stresses.The protective and defensive roles of these epidermal appendages are crucial to developing organs and can be attributed to the excellent combination of suitable structural traits and chemical reinforcement in the form of phenolic compounds,primarily fl avonoids.Both the formation of trichomes and the accumulation of phenolics are interrelated at the molecular level.During the early stages of development,non-glandular trichomes show strong morphological similarities to glandular ones such as the balloon-like apical cells with numerous phenolics.At later developmental stages,and during secondary wall thickening,phenolics are transferred to the cell walls of the trichomes.Due to the diff use deposition of phenolics in the cell walls,trichomes provide protection against UV-B radiation by behaving as optical fi lters,screening out wavelengths that could damage sensitive tissues.Protection from strong visible radiation is also aff orded by increased surface light refl ectance.Moreover,the mixtures of trichome phenolics represent a superfi-cial chemical barrier that provides protection against biotic stress factors such as herbivores and pathogens.Although the cells of some trichomes die at maturity,they can modulate their quantitative and qualitative characteristics during development,depending on the prevailing conditions of the external biotic or abiotic environment.In fact,the structure and chemical constituents of trichomes may change due to the particular light regime,herbivore damage,wounding,water stress,salinity and the presence of heavy metals.Hence,trichomes represent dynamic protective structures that may greatly aff ect the outcome of many plant–environment interactions.     

陆地棉SRO基因家族的鉴定及表达分析

SRO是植物特有的类RCD-ONE蛋白家族,在植物抵御各种生物和非生物胁迫过程中具有重要的作用。本研究利用生物信息学方法从陆地棉遗传标准系TM-1(Gossypium hirsutum L.acc.TM-1)基因组中鉴定到12个SRO基因家族成员。多重序列比对及进化树分析表明,12个陆地棉SRO均含有PARP和RST结构域,聚为3类,即A、B和C亚家族。转录组数据分析表明,TM-1全基因组中的Gh_D12G1442在茎中优势表达,Gh_D05G2064在萼片和雄蕊中优势表达;Gh_A05G3788在雄蕊中优势表达,Gh_A12G1318在雄蕊和纤维中优势表达;Gh_A12G2480、Gh_D12G2608、Gh_A05G2257和Gh_D05G2516在纤维中优势表达;Gh_A08G1390、Gh_D08G1685、Gh_A12G2663和Gh_D12G2054具有较为广泛的组织表达。逆境胁迫处理试验表明,Gh_A08G1390明显受冷处理和盐处理的诱导,Gh_D12G2054、Gh_D08G1685、Gh_A12G2663基因在不同的胁迫处理下受到不同程度的诱导。     

琥珀酸黄杆菌促生机理及其对多年生黑麦草生长和抗逆性的生理调控作用

为探究琥珀酸黄杆菌（Flavobacterium succinicans）对非生物胁迫下多年生黑麦草（Lolium perenne）的缓解效应,本试验研究了菌株DSM4002的生物学特性,并在盆栽条件下,分析了干旱（维持相对含水量（30±5）%处理7 d和14 d）、低温（4℃处理3 d和7 d）和盐胁迫（150 mM NaCl处理5 d和10 d）下根际接种DSM4002对多年生黑麦草生长和生理特性的影响。结果表明,DSM4002具有分泌吲哚乙酸（Indole-3-acetic acid,IAA）、溶磷和产铁载体能力,对壮观霉素、卡那霉素等具有抗性,对氯霉素敏感。同时,接种DSM4002能够提高正常生长、干旱、低温和盐胁迫下多年生黑麦草的生物量、抗氧化酶活性、可溶性糖和脯氨酸含量,降低相对电导率和丙二醛（Malondialdehyde,MDA）含量。综上,琥珀酸黄杆菌促进多年生黑麦草的生长与其自身具有分泌IAA、溶磷和产铁载体能力有关,而且它能够调节植物体内氧化还原平衡,从而增强多年生黑麦草的抗旱、抗寒和抗盐能力。