烤烟植株磷对矿质养分转运基因表达的影响及调控途径

【目的】作物体内磷与其他矿质养分之间存在复杂的交互作用。分析不同供磷水平对作物体内养分转运相关基因(启动子中含P1BS顺式调控元件)的表达水平,从基因水平深入理解磷与其它养分间交互作用的机理。【方法】设置砂培试验,供试烟草品种为K326(Nicotiana tabacum L.cv.K326),营养液中设低磷(0.1 mmol/L)、正常(对照,1 mmol/L)和高磷(5 mmol/L)3个磷供应水平,于烟草幼苗移栽4周后开始处理,5周后打顶,6周后取样,并分为根、茎、叶和腋芽,测定磷和其他元素浓度,鉴定启动子序列中含有磷调控顺式元件P1BS的基因,运用实时荧光定量PCR分析其中一些基因在缺磷和高磷条件下的相对表达量,采用生物学方法研究磷调控信号通路的中心转录因子NtPHR2调控钾、镁转运蛋白的途径。【结果】与对照相比,低磷和高磷处理均抑制烟株生长和地上部干物质量的积累;高磷处理植株各部位磷的积累均显著增加;地上部叶片中的钾、镁浓度随供磷水平的增加而提高,钙浓度在低磷和高磷处理下均不同程度地降低;根系中的铜、铁、锌浓度受供磷水平的影响不显著,而低磷显著降低了锰的吸收但促进锰向地上部转移。本研究在根系中共鉴定到86个含P1BS顺式调控元件的编码矿质营养转运蛋白的基因,选择其中磷、钾、钙、镁、铁、铜和锌转运蛋白基因12个进行RT-qPCR扩增分析,发现它们在低磷和高磷条件下的相对表达量不同。低磷和高磷处理均上调了磷、钾、钙、镁、铁转运蛋白基因表达量;低磷上调铜转运蛋白基因表达量而高磷下调其表达量;而两个锌转运蛋白基因一个在低磷和高磷时表达下调,另一个则表达上调。通过生物学方法证实了中心转录因子NtPHR2通过结合P1BS顺式元件直接调控钾和镁转运蛋白基因。【结论】缺磷和过量供磷均会抑制烟株生长,影响包括磷在内的养分的吸收和转运。增加磷供应水平可显著提高烟株各部位磷的浓度,提高钾和镁浓度,缺磷和过量供磷对地上部各组织其他养分浓度有负面影响。各营养元素转运蛋白基因的相对表达量受低磷和高磷的影响不同,可能与磷信号通路对其转运蛋白的调控途径有关。NtPHR2通过结合P1BS顺式元件直接调控钾和镁转运蛋白基因,因此,增加磷的供应提高了烟株磷的吸收,进而可能直接上调了钾和镁的吸收及转运。

Studies on the Mechanism of Single Basal Application of Controlled-Release Fertilizers for Increasing Yield of Rice (Oryza sativa L.)

This paper was to explore the mechanism of single basal application of controlled-release fertilizers for increasing yield of rice （Oryza sativa L.）. Pot trials and cylinder trials were carried out from 2002 to 2005 to study the influences of single basal application of 3 controlled-release fertilizers on the changes of soil available N, root development, senescence and lodging resistance at late growth stages. Results showed that at 30 days after fertilization, single basal application of controlled-release fertilizers coated with vegetal-substance （CRF1） and polymer materials （CRF3） increased soil available N to 12.0 and 147.9%, respectively, in comparison to split fertilization of rice-specific fertilizer （RSF1）. Treatments of the two CRFs obviously benefited the development of root system, resulting in greater rice root weights with extensive distribution and higher root activity. In addition, the two CRF treatments, in comparison to RSF1, enhanced chlorophyll consents of the flag leaves to 9.5 and 15.5%, and soluble protein up to 89.7 and 108.0% respectively. Application of the two CRFs also made the base of rice stems strong and large, declined the proportion of shoot and root, increased root depth index. Though relatively low K rate, single basal application of the CRF3 coated with NH4MgPO4 could also promote the development of root system, enhance root activity and some physiological functions of flag leaves. Based on these results, it was concluded that major mechanisms for increasing rice yield by single basal application of the CRFs should be attributed to grater soil available N supply, superior development of root systems, better nutrient absorption capacity, slower senescence and enhancement of lodging resistance at late stages.

驾驶室橡胶减震器设计研究

本文通过橡胶产品性能特性,研究橡胶刚度计算方法及橡胶减震系统减震效果评价方法。并以一种常用驾驶室橡胶减震系统的减震结构为例,通过减震器刚度的计算以及振动传递率的计算,以及和实验室刚度测量结果和减震效果测量结果对比,验证了本文计算方法的有效性。从而为驾驶室减震系统设计提供了有效的计算方法,解决了目前行业内减震设计长期依靠类比设计的难题。