Factors affecting Agrobacterium tumefaciens-mediated transformation in several black poplar clones

Transient expression of the uidA reporter gene was used in preliminary experiments with two oncogenic and two disarmed Agrobacterium tumefaciens strains in order to test the efficiency of T-DNA transfer to N084 x Populus nigra and N107 x P. nigra clones. The oncogenic strain A281 pKIWI105 produced the highest average number of GUS spots per leaf disc. In order to optimize the production of transgenic plantlets from different P. nigra clones (San Giorgio, Jean Pourtet, N084 x P. nigra and N107 x P. nigra, respectively), two A. tumefaciens strains (GV2260 p35S GUS, A281pKIWI105) and bacterial concentrations (7×10⁸; 1.2×0⁹ bacteria ml^-1) were used. Following co-cultivation with A281 pKIWI105, the frequency of leaf discs producing kanamycin-resistant calli was not significantly different between the clones and bacteria concentrations used. Transformed shoots were regenerated from all clones, except for Jean Pourtet. Co-cultivation of leaf discs with GV2260 p35S GUS produced very few calli which died when transferred to selective regeneration medium. In addition, the effects of acetosyringone and leaf wounding were evaluated for the San Giorgio and Jean Pourtet clones, using the same strains. Factors which significantly affected the transformation efficiency of leaf explants were the P. nigra clone, the A. tumefaciens strain, and the presence of acetosyringone. Genetic transformation of calli and regenerated plantlets was confirmed by their ability to grow and root on Woody Plant Medium containing kanamycin, by histochemical -glucuronidase assays, and Southern blot hybridization analyses.Abbreviations BA benzyladenine - GUS -glucuronidase - IBA indolebutyric acid - MS Murashige and Skoog - NAA -naphthaleneacetic acid - nptII neomycin phosphotransferase II gene - uidA -glucuronidase gene - WPM Woody Plant Medium     

Ribulose-1, 5-bisphosphate carboxylase activity,chlorophyll and protein concentrations in differentPopulus clones

Ribulose-1,5-bisphosphate carboxylase activity (RuBPC), chlorophyll (chl) and protein (prot) concentrations and chlorophyll/protein (chl/prot) ratios were determined in five differentPopulus clones together with their maximal net CO₂ uptake rates (P_max). A classic reference clone (Populus ×euramericana “Robusta” (Dode) Guinier) was compared with four recently selected euramerican and interamerican crossings. Chl/prot ratio and RuBPC activity varied among the different clones, while chl a/chlb ratio showed only a very low coefficient of variation (1.7%) for the five clones. Poplar clone “Robusta” could be distinguished from the recent faster growing clones based on the different biochemical characteristics. A significant correlation was found between both total chl concentration and chl/prot ratio with P_max for the five clones.     

小黑杨花粉植株H_1株系间变异及其选择利用的研究

小黑杨(Populus xiaohei T.S.Hwang ex C.Wang et Tung)花药离体培养获得单倍体植株,经14年的生长观察,发现花粉植株间表现出明显分离。选出19个株系进行田间比较试验,统计分析,结果发现材积生长差异显著。可从中选出优良株系加以利用,并提出杨树单倍体育种程序。     

Flavonoid data and populational observations in support of hybrid status for Populus acuminata

Flavonoid distribution and populational composition at the collection sites of several samples of Populus acuminata strongly suggest that this taxon is an inter-sectional hybrid between P. angustifolia, sect. Tacamahaca and any one of two or three different species of the section Aigeiros, when the entire range is considered. In the vicinity of the type locality, the Aigeiros parent is P. sargentii. Within any population, foliage of trees of P. acuminata is characterized by morphological intermediacy and an essentially additive flavonoid profile, as compared to the two parental taxa present. In habit the trees resemble those of P. sargentii, and habitats at the collection sites were found to be somewhat intermediate. Fifteen flavonoid compounds were consistently present in samples of the putative hybrid. Twelve of these had diagnostic value because they were absent in one of the parental species. One compound, apigenin 7-O-diglucoside, was found only in P. acuminata. In part, our identifications correspond to compounds reported by Crawford in a morphological and chemical study of P. acuminiata.     

基于整树称重法的Granier经验公式对毛白杨树干液流测定的适用性

为了评估Granier经验公式在树干液流测定中的适用性,以毛白杨为对象,利用热扩散式探针法(TDP)测定树木的液流速率,以整树称重法进行同步测定,对比分析Granier经验公式在毛白杨树干液流测定中是否存在误差,并对整树称重法测定的蒸腾速率与热扩散法测定的温差系数K进行幂指数回归拟合,建立校正的Granier公式。结果表明:与整树称重法测定的蒸腾速率相比,通过Granier经验公式计算的液流速率低估了67.7%;建立了毛白杨的Granier校正公式F_d=0.0135K^0.6952(R²=0.77),校正后Granier公式的计算结果与整树称重法测定的蒸腾速率相比仅降低了3.4%,具有较好的一致性。因此,采用Granier经验公式计算毛白杨树干液流速率需进行校正。     

长白山白桦山杨次生林细根形态特征和解剖结构对氮沉降的响应

根系作为植物与土壤物质交换和养分循环的桥梁,长期以来一直是生态学研究的热点。于2017年7月植物生长季,对长白山模拟11年氮(N)沉降控制试验样地的白桦(Betula platyphylla)山杨(Populus davidiana)天然次生林进行了根系采样,并利用根序法研究了根系形态特征和解剖结构对不同梯度N添加处理的响应,旨在探求两物种根系之间潜在生态联系。本试验共设置了三个N添加梯度,分别为对照(CK,0 g N m~(-2 )a~(-1))、低N处理(T_L,2.5 g N m~(-2 )a~(-1))和高N处理(T_H,5.0 g N m~(-2 )a~(-1))。研究结果如下:1)T_L显著抑制白桦和山杨前三级细根皮层厚度的生长。白桦通过增加皮层细胞直径(一级根增加了72.77%,二级根增加了53.22%,三级根增加了39.96%)但减少皮层层数来降低皮层厚度,而山杨主要通过皮层细胞直径的减少(一级根下降了40.80%,二级根下降了28.17%)来降低其皮层厚度。2)T_H显著抑制山杨前三级细根生长。主要通过增加皮层厚度(一级根增加了68.78%,二级根增加了50.81%,三级根增加了88.53%)以及降低导管横截面积来抑制吸收养分,从而达到影响生长的目的。3)白桦T_H相比于T_L细根直径呈抑制生长状态。其主要通过抑制中柱直径(一级根下降了17.61%,二级根下降了16.89%,三级根下降了20.62%)的生长来实现。以上结果表明,在同一立地条件下,白桦和山杨的细根对不同浓度N沉降的响应方式不同。     

基于地面LiDAR数据的塔里木河下游胡杨林结构参数反演

以塔里木河下游天然胡杨林为研究对象,利用Riegl VZ-1000型地面激光扫描仪(Terrestrial Laser Scanning, TLS)获取离河道不同距离的8个样方内513棵胡杨的三维点云数据,通过建立冠层高度模型、Hough变换等方法获取单木株数和结构参数,并与传统的每木检尺实测数据和无人机(Unmanned Aerial Vehicle, UAV)低空影像进行对比,验证激光雷达方法的测树精度;对TLS获取的胡杨树形参数进行相关性分析,并建立关系模型;探讨不同水胁迫条件(不同离河道距离,不同地下水埋深)对胡杨单木结构参数的影响;最后按不同径级划分胡杨的年龄,得出各龄级胡杨所占比例。结果表明:(1)TLS能够高精度获取不同密度和长势的胡杨单木株数和结构参数,单株准确分割比率为94%—100%,相对于UAV低空影像更为准确;(2)TLS获取的胡杨树高(Tree height,TH)、胸径(Diameter at breast height, DBH)、冠幅直径(Crown diameter,CD)和冠幅面积(Crown area,CA)与传统实测值拟合度R~2较高,分别为0.95、0.97、0.77和0.84,表明实测数据和TLS获取数据无明显差异;(3)胡杨CD、CA分别与TH呈显著正相关,其相关性系数为0.73、0.67;基于此构建了胡杨TH与CD的关系模型,即TH=2.6274×CD~(0.706),R~2为0.64;(4)根据径级划分胡杨年龄段可知,DBH为15—30 cm的近熟林比例最大,占8个样方内监测胡杨总株数的47%,表明胡杨种群年龄结构相对稳定并总体态势良好,呈现了生态输水对塔河下游胡杨种群恢复有明显的促进作用。总之,激光雷达技术能够客观反映胡杨树形结构参数,可替代耗力、耗费、耗时的传统实测方法,为时时掌握胡杨林生长发育、长势动态以及多尺度、多时相生态耗水研究提供高精度信息,为干旱区荒漠河岸林的有效保护与可持续管理提供科学依据。     

荒漠河岸胡杨林生态系统能量分配及蒸散发

生态输水工程使得黑河下游地区荒漠河岸林的面积得到了恢复,为进一步巩固生态恢复的成果,非常有必要深入研究胡杨林生态系统的水热交换过程及其对环境因子和人类活动的响应机理。基于涡度相关技术,对2013-2016年荒漠河岸胡杨林生态系统的水热交换过程进行了研究,得出的主要结论如下：（1）生长季生态系统的能量消耗以潜热通量为主,波文比为0.21;非生长季则以感热通量为主,波文比为3.61;春季和秋季的灌水过程,使得胡杨生长前期和后期的潜热通量值较高,直接影响着胡杨林生态系统的能量分配。（2）灌水的时间改变了潜热通量和蒸散发的季节变化过程,而灌水的量决定着春季和秋季潜热通量和蒸散量的年际差异。（3）2014-2016年,生态系统的年蒸散量和生长季蒸散量平均分别为1092 mm和932 mm。荒漠河岸胡杨林生态系统的蒸散量主要受系统水分状况（灌水量）及植物生长状况的影响。     

杨树受机械损伤与光肩星天牛危害的防御性反应

杨树是我国“三北”地区防护林建设的主栽树种,自20世纪70年代以来长期受到光肩星天牛的严重危害。北抗杨对光肩星天牛有一定的抗性,但产生抗性的生化机制尚不清楚。本研究采用试剂盒法与高效液相色谱法以未受害、机械损伤、虫害北抗杨为研究材料,对其树皮和木质部中的次生代谢产物和防御酶含量进行检测,以探索其抗性机制。结果表明,北抗杨受到机械损伤和光肩星天牛危害后其反应不同:1)次生代谢产物,北抗杨受到机械损伤后,树皮中的水杨苷和白杨甙含量显著上升,槲皮苷含量降低;而受光肩星天牛危害后,树皮中的水杨苷和槲皮苷含量显著上升,白杨甙含量无显著变化。机械损伤的北抗杨木质部总酚含量高于虫害与未受害木质部,后两者间无显著差异;光肩星天牛危害的北抗杨木质部白杨甙和亚麻木酚素含量高于机械损伤木质部与未受害木质部。遭受机械损伤与虫害后北抗杨木质部的总酚苷含量显著高于未受害木质部。2)防御酶活性分析表明,与未受害北抗杨树皮相比,受到机械损伤与虫害后的树皮苯丙氨酸解氨酶(PAL)活性显著升高,但两者间无差异;受到机械损伤与虫害后的树皮超氧化物歧化酶(SOD)活性高于未受害树皮,且机械损伤树皮高于虫害树皮;北抗杨受机械损伤与虫害后木质部中的过氧化物酶(POD)活性高于未受害木质部,但两者间无差异。3)与未受害北抗杨相比,北抗杨受机械损伤、虫害后部分次生代谢物和防御酶都有不同程度的增加,推测这些物质可能与北抗杨抗逆性反应有关。     

丛枝菌根真菌对青杨抗溃疡病生物量和抗病酶活性的影响

本研究以青杨Populus cathayana 1年生扦插苗为试验材料,接种丛枝菌根真菌（arbuscular mycorrhizal fungi,AMF）异形根孢囊霉Rhizophagus irregularis和杨树溃疡病菌聚生小穴壳菌Dothiorella gregaria,测定AMF对青杨根茎叶生物量,丙二醛（MDA）、脯氨酸和茎部纤维素含量,超氧化物歧化酶（SOD）、过氧化氢酶（CAT）、多酚氧化酶（PPO）、几丁质酶、多聚半乳糖醛酸酶和果胶甲基酯酶等抗病酶活性的影响。结果表明,接种AMF可以增加青杨根茎生物量,增加茎纤维素含量来增强树势,降低溃疡病发病率;接种AMF能够显著降低感病杨树茎部和根系MDA含量,增加叶片和根系脯氨酸含量,提高根茎叶PPO活性、茎SOD活性和叶片CAT活性;接种AMF前期可以提高茎和根系几丁质酶和β-1,3-葡聚糖酶活性,也可以提高叶片和茎多聚半乳糖醛酸酶、果胶甲基酯酶活性,接种病原菌条件下AMF效果更加显著。结论认为,AMF通过积累脯氨酸,降低MDA含量,提高SOD、CAT和PPO活性,增强杨树抗溃疡病能力;同时也可提高多聚半乳糖醛酸酶和果胶甲基酯酶活性来抑制病原菌菌丝的生长,减弱菌丝的扩展能力,增强杨树抗病性。