白桦木质部蛋白提取方法的建立1）

以白桦（ Betula platyphylla Suks．）木质部为试验材料,分别采用TCA—丙酮提取、酚提取和试剂盒提取3种方法提取白桦木质部总蛋白。利用试剂盒定量和聚丙烯酰胺凝胶电泳、双向电泳技术比较3种提取方法的蛋白质提取效率、提取质量。同时对酚提取法进行改良,建立适用于白桦木质部蛋白的提取方法。研究结果表明,改良的酚提取法提取的白桦木质部蛋白提取量最大,电泳条带清晰,丰富,质量较高。2－DE电泳得到的蛋白凝胶背景干净,蛋白质点清晰。因此,改良的酚提取法是较适合于白桦木质部蛋白的提取方法。     

干旱、外源ABA和不同pH溶液对玉米木质部汁液pH的影响

干旱胁迫和外源ABA处理玉米幼苗后 ,根、茎的木质部汁液pH升高 ,叶中木质部汁液 pH略有降低 ;不同 pH外源溶液处理也都不同程度改变了木质部汁液 pH ,其中以 pH值为 6的外源溶液处理后的效果最明显。     

基于数值模拟的栓塞修复过程中AE信号分析

为探讨木质部栓塞修复过程监测到大量AE信号现象的原因,基于Rayleigh-Plesset方程建立描述栓塞修复过程中空化泡的运动方程,并用数值模拟方法得到空化泡运动方程的解,对AE信号进行动力学分析。结果表明:当木质部液水势升高时,空化泡会塌缩为半径较小的气泡。但经过一次塌缩并不会使栓塞修复。在压强升高的情况下,气泡会经多次塌缩直到形成稳定的微小气泡,栓塞才会完全修复。在气泡多次塌缩的过程中,气泡半径减小,但是并不是单调减小而是以减幅振动的方式减小,从而形成振源,成为AE信号的来源之一。     

Coast live oak, Quercus agrifolia, susceptibility and response to goldspotted oak borer, Agrilus auroguttatus, injury in southern California

Oak mortality is often associated with a complex of decline factors. We describe the morphological and physiological responses of coast live oak, Quercus agrifolia Née, in California to an invasive insect, the goldspotted oak borer (GSOB), Agrilus auroguttatus Schaeffer (Coleoptera: Buprestidae), and evaluate drought as a potential inciting factor. Morphological traits of 356 trees were assessed and physiological traits of 70 of these were monitored intensively over one growing season. Morphological characteristics of tree health included crown thinning and dieback; bole staining resulting from larval feeding; density of GSOB adult exit holes; and holes caused by woodpecker feeding. These characteristics were used to rank GSOB infestation/injury into four classes, and taken together, they explained 87% of the variation in a principal component analysis. Drought stress on various size/age and infestation classes of Q. agrifolia was measured by assessing branchlet pre-dawn and solar noon xylem water potential, leaf cell turgor potential, and water use efficiency over one growing season. Both morphological and physiological traits were highly variable in mature and old growth trees. Early summer plant water status (branchlet xylem water potential and water use efficiency) was similar between uninfested and newly colonized trees, suggesting that GSOB are not pre-selecting drought-stressed Q. agrifolia for oviposition. By late summer, leaf water and cell turgor potentials were lower in infested than in uninfested mature trees, suggesting that GSOB infestation causes drought stress in these trees. Among the tree size/age classes, infested old growth trees exhibited the greatest change in water use efficiency over the growing season, and showed greater morphological injury symptoms of decline than infested mature trees. Morphological attributes of decline in Q. agrifolia associated with GSOB were correlated weakly with increasing physiological drought stress among infestation classes of trees. We propose that the collection of morphological responses of Q. agrifolia to GSOB described here can be used to monitor the future expansion of the GSOB distribution as well as the GSOB-induced decline of Q. agrifolia in California.     

杨树木质部特异启动子MDCesAP的改造及功能检测

木质部特异表达的强启动子有助于外源目的基因在植物木质部中高效表达。将2个杨树木质部特异启动子MDCe-sAP串联在一起,置换植物表达载体pBI121上的35S启动子,构建成pDMDCesAP-GUS植物表达载体,通过农杆菌介导,并采用叶盘法转化烟草,获得烟草抗性植株。β-葡糖醛酸酶(GUS)活性检测结果表明,该串联启动子DMDCesAP具有木质部特异性,有望应用于桑天牛寄主树种的抗虫转基因研究。     

株行距配置对玉米根系性状及产量的影响

以郑单958为材料, 采用田间试验方法, 在50 025株/hm²、67 500株/hm²、100 050株/hm²密度下分别设两种株行距配置, 探讨增密条件下调控株行距配置对玉米根系性状及产量影响。结果表明, 3个种植密度下总体表现为小行距种植方式在0～60 cm土层内的根重密度、根长密度及根表面积密度均高于大行距处理。50 025株/hm²下吐丝期时0～60 cm土层内的根重密度和根长密度在两个株行距配置间差异显著(P<0.05), 两个株行距配置的根表面积密度在10叶展、吐丝期和吐丝后25 d差异显著(P<0.05);67 500株/hm²下不同时期两个株行距配置根重密度差异显著(P<0.05), 根长密度和根表面积密度在10叶展和吐丝后25 d差异显著(P<0.05);100 050株/hm²下, 两个株行距配置间根重密度和根长密度在10叶展和吐丝后25 d差异显著(P<0.05), 不同时期根表面积密度差异显著(P< 0.05)。同一密度下缩行增株后单株木质部伤流液体积增大, 根系供应能力增强, 产量增加, 50 025株/hm²、67 500株/hm²下产量分别提高了6.76%和4.89%。不同时期0～60 cm土层内根重密度、根长密度和根表面积密度与产量呈正相关, 其中10叶展时各根系性状均与产量呈显著正相关。     

土壤水分状况对小麦叶片超声波信号发射及木质部脆弱性的影响

土壤干旱引发植物木质部导管发生“空穴化”，对植物生长发育及抗旱生理具有重要影响。本研究通过检测小麦叶片超声波（AE）信号发射的变化，在田间充分灌水及控水条件下对冬小麦（Triticum aestivum L.）品种石新733主要生育期叶片木质部导管空穴化及气栓塞发生特性进行了研究。结果表明，叶片AE信号一般6:00~8:00开始发生，夜间21:00~3:00期间停止。土壤干旱时植株叶片木质部气栓塞发生程度显著高于良好供水的植株。拔节至灌浆盛期控水处理24 h AE 总量高于足水处理，其中开花期至籽粒形成初期处理间差别最大，控水处理24 h AE平均为足水处理的4.6倍。但籽粒灌浆中后期控水处理土壤水分胁迫进一步加重时，24 h AE 反而下降至接近甚至低于足水处理，出现“AE衰减现象”。叶片AE累积发生值和叶水势(Ψl)的变化关系符合Logistic曲线模型（脆弱曲线）。拟合结果表明，一般小麦Ψl降至约－1.00 MPa 时导管空穴化发生速率最高。土壤干旱条件下植株叶片木质部脆弱性显著增高，木质部安全性明显降低。土壤干旱时叶片空穴化和气栓塞增高的主要原因是导管对空穴化的抵御能力下降，而叶水势的影响较小。     

有机物对红外光谱技术测定植物叶片和茎秆水δ18O和δD的影响

植物叶片、茎秆和土壤水δ18O和δD是研究土壤植被大气系统生态水文循环过程的重要示踪剂。与传统的稳定同位素质谱(IRMS)技术相比,稳定同位素红外光谱(IRIS)技术具有测量速度快、运行成本低等优势,将促进稳定同位素生态学的发展。但是利用低温真空蒸馏抽提技术获得的植物叶片和茎秆水中含有甲醇和乙醇类有机污染物,造成δ18O和δD的IRIS测量值偏离IRMS测量值(2.64±0.43)‰和(3.6±0.8)‰,超过了仪器精度。本研究利用纯水混入不同浓度的色谱纯甲醇或乙醇,结合Los Gatos公司的光谱分析软件确定甲醇(NB)和乙醇(BB)类物质污染程度的光谱度量值,建立了δ18O和δD的光谱污染校正方法。研究表明,同一台分析仪建立的校正曲线无明显的时间漂移;不同分析仪建立的校正曲线存在显著差异;IRIS校正值与IRMS测量值的交叉验证表明,IRIS测定冬小麦和夏玉米叶片和茎秆水的δ18O和δD可以被准确地校正,与IRMS的差值分别为(0.11±0.12)‰和(0.7±0.4)‰。     

Diurnal variations in uptake,transport and assimilation of NO3 ‐and efflux of OH‐ in maize plants

Maize plants, grown for 7 and 21 days on a nutrient solution with NO₃ ^‐ as the sole nitrogen source showed a clear diurnal pattern with respect to the in vivo NRA. Especially in roots dark/light fluctuations of the enzyme activity were high. Also in NO₃ ^‐ uptake, OH^‐ efflux and endogenous content of water soluble carbohydrates a diurnal variation was found. The plant age did not significantly affect the daily rhythm.

Because day/night changes of the in vivo root NRA and nitrate uptake were proportional, the relative content of reduced N in the xylem sap of the plants was constant during a day/night interval. At both day 7 and day 21 about 40–50% of the N was transported via the xylem as amino N. As a result of non‐synchronous variation of the specific root and shoot NRA, root reduction capacity showed a great within‐day variation. It varied between 20 and 40% of the whole plant reduction capacity. Since the ratio N‐organic to N‐total in the xylem sap was about 0.5, cycling of organic nitrogen was very likely in these maize plants.