Characteristics of microRNAs and Target Genes in Maize Root under Drought Stress

Maize (Zea mays) is an important multi-functional crop. The growth and yield of maize are severely affected by drought stress. Previous studies have shown that microRNAs (miRNAs) in maize play important roles in response to abiotic stress; however, their roles in response to drought stress in maize roots is unclear. In our study, we found 375 miRNAs in the roots of 16 inbred lines. Of the 16 lines, zma-MIR168, zma-MIR156, and zma-MIR166 were highly expressed, whereas zma-MIR399, zma-MIR2218, and zma-MIR2275 exhibited low expression levels. The expression patterns of miRNA in parental lines and their derived RILs are different. Over 50% of miRNAs exhibited a lower expression in recombinant inbred lines than in parents. The expression of 50 miRNAs was significantly altered under water stress (WS) in at least three inbred lines, and the expression of miRNAs in drought-tolerant lines changed markedly. To better understand the reasons for miRNA response to drought, the degree of histone modifications for miRNA genes was estimated. The methylation level of H3K4 and H3K9 in miRNA precursor regions changed more noticeably after WS, but no such phenomenon was seen for DNA methylation and m6A modification. After the prediction of miRNA targets using psRNATarget and psRobot, we used correlation analysis and qRT-PCR to further investigate the relationship between miRNAs and target genes. We found that 87 miRNA–target pairs were significantly negatively correlated. In addition, a weighted gene co-expression network analysis using miRNAs, as well as their predicted targets, was conducted to reveal that miR159, miR394, and miR319 may be related to maize root growth. The results demonstrated that miRNAs might play essential roles in the response to drought stress.     

Maize Transcription Factor ZmARF4 Confers Phosphorus Tolerance by Promoting Root Morphological Development

Plant growth and development are closely related to phosphate (Pi) and auxin. However, data regarding auxin response factors (ARFs) and their response to phosphate in maize are limited. Here, we isolated ZmARF4 in maize and dissected its biological function response to Pi stress. Overexpression of ZmARF4 in Arabidopsis confers tolerance of Pi deficiency with better root morphology than wild-type. Overexpressed ZmARF4 can partially restore the absence of lateral roots in mutant arf7 arf19. The ZmARF4 overexpression promoted Pi remobilization and up-regulated AtRNS1, under Pi limitation while it down-regulated the expression of the anthocyanin biosynthesis genes AtDFR and AtANS. A continuous detection revealed higher activity of promoter in the Pi-tolerant maize P178 line than in the sensitive 9782 line under low-Pi conditions. Meanwhile, GUS activity was specifically detected in new leaves and the stele of roots in transgenic offspring. ZmARF4 was localized to the nucleus and cytoplasm of the mesophyll protoplast and interacted with ZmILL4 and ZmChc5, which mediate lateral root initiation and defense response, respectively. ZmARF4 overexpression also conferred salinity and osmotic stress tolerance in Arabidopsis. Overall, our findings suggest that ZmARF4, a pleiotropic gene, modulates multiple stress signaling pathways, and thus, could be a candidate gene for engineering plants with multiple stress adaptation.     

An ABA Functional Analogue B2 Enhanced Salt Tolerance by Inducing the Root Elongation and Reducing Peroxidation Damage in Maize Seedlings

Salt stress negatively affects maize growth and yield. Application of plant growth regulator is an effective way to improve crop salt tolerance, therefore reducing yield loss by salt stress. Here, we used a novel plant growth regulator B2, which is a functional analogue of ABA. With the aim to determine whether B2 alleviates salt stress on maize, we studied its function under hydroponic conditions. When the second leaf was fully developed, it was pretreated with 100 µM ABA, 0.01 µM B2, 0.1 µM B2, and 1 µM B2, independently. After 5 days treatment, NaCl was added into the nutrient solution for salt stress. Our results showed that B2 could enhance salt tolerance in maize, especially when the concentration was 1.0 µMol·L⁻¹. Exogenous application of B2 significantly enhanced root growth, and the root/shoot ratio increased by 7.6% after 6 days treatment under salt stress. Compared with control, the ABA level also decreased by 31% after 6 days, which might have resulted in the root development. What is more, B2 maintained higher photosynthetic capacity in maize leaves under salt stress conditions and increased the activity of antioxidant enzymes and decreased the generation rate of reactive oxygen species by 16.48%. On the other hand, B2 can enhance its water absorption ability by increasing the expression of aquaporin genes ZmPIP1-1 and ZmPIP1-5. In conclusion, the novel plant growth regulator B2 can effectively improve the salt tolerance in maize.     

香豆素系列荧光染料的液相色谱分析

本文运用反相高效液相色谱法,以6只香豆素染料为研究对象,研究了流动相组成对它们色谱保留行为的影响,通过调整流动相的种类和组成比例,最终选用C18色谱柱为分析柱,乙腈-水为流动相,紫外吸收检测器为检测手段,建立了既适用于这6只香豆素系荧光染料的单一分析又适用于它们混拼分析的方法,解决了这6只染料混拼时的分析问题.     

A Comparative Study on Changes and Relationships of Kernel Biochemical Components in Different Types of Maize

A great deal of genetic variability and breeding efforts have yielded a number of specialty maize types. Little is known about how the off‐target traits in specialty maize kernel have changed and how they compare to those of standard maize genotypes. In this study, we compared the normal (NORMAL), high‐oil (HOM) and high‐protein maize (HPM) genotypes in terms of oil, protein, fatty acids and some mineral components. We also investigated the relationships among the evaluated traits in different kernel types. We detected a significant variation among the maize types for all of the investigated traits. Specialty maize genotypes had a superior performance for the traits they were specifically bred for, as well as kernel mineral content over the normal genotypes. HOM and HPM had similar values in terms of their fatty acid composition. However, they were different from the standard genotypes, with higher oleic and lower linolenic acid levels, which indicates that the specialty maize genotypes possess a better oil quality. Correlation analysis revealed that only three pairs of correlations out of 46 values had the same sign and a similar level of significance in different types. Such similarities or differences in correlation values for different types should be taken into account in the efforts for developing high quality maize genotypes.     

Genome-Wide Identification of Auxin Response Factors in Peanut (Arachis hypogaea L.) and Functional Analysis in Root Morphology

Auxin response factors (ARFs) play important roles in plant growth and development; however, research in peanut (Arachis hypogaea L.) is still lacking. Here, 63, 30, and 30 AhARF genes were identified from an allotetraploid peanut cultivar and two diploid ancestors (A. duranensis and A. ipaensis). Phylogenetic tree and gene structure analysis showed that most AhARFs were highly similar to those in the ancestors. By scanning the whole-genome for ARF-recognized cis-elements, we obtained a potential target gene pool of AhARFs, and the further cluster analysis and comparative analysis showed that numerous members were closely related to root development. Furthermore, we comprehensively analyzed the relationship between the root morphology and the expression levels of AhARFs in 11 peanut varieties. The results showed that the expression levels of AhARF14/26/45 were positively correlated with root length, root surface area, and root tip number, suggesting an important regulatory role of these genes in root architecture and potential application values in peanut breeding.     

以叶绿素为标准评价阿维菌素和甲维盐对玉米幼苗的安全性

在人工气候培养箱中,待玉米幼苗长至三叶一心时,在第三叶片上涂抹30μL的各浓度的阿维菌素和甲维盐,24 h后测定叶绿素的含量.结果表明,阿维菌素浓度为600～1 200倍,甲维盐浓度为500～1 000倍时,它们对玉米安全.     

表面活性剂对三水碳酸镁晶须形貌的影响研究

采用低温液相法制备三水碳酸镁晶须晶体,研究了不同表面活性剂对晶须晶体形貌的影响,研究发现:有机表面活性剂的作用效果没有无机表面活性剂的作用效果好,采用磷酸二氢钾作为表面活性剂时,制备的三水碳酸镁晶须结晶发育完整,晶须长径比大.     

超声诊断不同类型异位妊娠120例的临床应用

目的分析超声诊断不同类型异位妊娠的临床价值。方法选择我院2007年6月至2010年6月收治的120例经超声确诊的异位妊娠患者作为研究对象,采用美国GE-LOGIQ-400、Acuson128XP/10c彩色多普勒超声诊断仪。彩色多普勒超声诊断仪进行检查,总结分析不同类型异位妊娠的超声声像图表现。结果超声诊断的120例异位妊娠患者,经手术及病理证实者112例,诊断符合率93.3%。120例超声诊断的异位妊娠患者中,未破型、破裂型、流产型、陈旧型异位妊娠患者的超声声像图表现均有其自身的特点。结论超声对异位妊娠的诊断符合率较高,不同类型的异位妊娠超声声像图具有不同的特点,因此,临床诊断异位妊娠时同时结合HCG及患者自身的因素而确诊。     

两类PE-HD/E-TMB共混物的脆韧转变及断面形态

用自制增韧母料(E-TMB)分别与2200J型高密度聚乙烯(PE-HD)(HE1)和2911型PE-HD(HE2)热机械共混制得HE1/E-TMB和HE2/E-TMB共混物,用力学性能测试法和扫描电子显微镜研究了两类共混物的脆韧转变和断面形态。结果表明,HE1/E-TMB共混物比HE2/E-TMB共混物在弹性体含量较低的情况下发生脆韧转变,二者的脆韧转变区分别是共混物弹性体质量分数的3%～10%和10%～14%;弹性体质量分数为8%时,HE1/E-TMB共混物的冲击断面为韧性断裂,HE2/E-TMB共混物的冲击断面为脆性断裂,二者属于不同的断裂机理。     

Growth Inhibition and Root Ultrastructure of Cucumber Seedlings Exposed to Allelochemicals from Rye (Secale cereale)

Inhibition of "Calypso" cucumber seedling growth by rye allelochemicals, 2(3H)-benzoxazolinone BOA and 2,4-dihydroxy-1,4(2H)-benzoxazin-3-one DIBOA, was studied by analyzing the growth of seedling tissues and organs. Light and electron microscopy of seedling root cells were also carried out to investigate the mechanism(s) of root growth inhibition and mode of action of these compounds. BOA inhibited root elongation and reduced the number of cucumber lateral roots by 77 and 100% at 0.1 and 0.43 mg BOA/ml deionized (DI) water, respectively. DIBOA also inhibited root growth, but did not affect the number of lateral roots. BOA increased size of cucumber cortical root cells fivefold, but DIBOA had no effect. Both compounds reduced the regeneration of root cap cells and increased the width of cortical cells resulting in increased root diameter. BOA and DIBOA caused increased cytoplasmic vacuolation, reduced ribosome density and dictyosomes, reduced number of mitochondria, and reduced lipid catabolism. Starch granules in amyloplasts of seedling roots treated with BOA and DIBOA were also greatly reduced compared to the control. Changes in cellular ultrastructure indicated that BOA and DIBOA reduced root growth by disrupting lipid metabolism, reducing protein synthesis, and reducing transport or secretory capabilities.     

化学还原法制备不同形貌的纳米银粉

采用化学还原法,分别以还原糖溶液、聚乙二醇、三乙醇胺为还原剂制备纳米银粉,对还原机理进行了分析,探讨了还原剂种类、酸碱度pH值、溶液浓度、反应温度等对银粉形貌及粒度大小的影响。结果表明,分别以还原糖溶液、聚乙二醇、三乙醇胺为还原剂,制备了薄片状、棒状、类球形或线形纳米银粉,这主要与还原剂溶液的pH值有关。以三乙醇胺做还原剂40℃时,可以制得均匀的类球状纳米银粉。     

微生物降解褐煤产生的黄腐酸对玉米幼苗生长的影响

通过研究褐煤经微生物降解获得的黄腐酸所制成的包衣剂对玉米幼苗株高、叶绿素含量及根活力的影响,发现200mg／kg黄腐酸包衣的玉米在生长第15d时,幼苗株高比对照提高5．60cm,而采用500mg／kg黄腐酸包衣的玉米叶绿素含量增加了0．27mg／g,根系活力增加了70．93g／（g·h）。实验结果表明,低浓度的黄腐酸能促进玉米的生长、增加叶绿素含量及增强根活力,而高浓度的黄腐酸对三者均有抑制作用。     

不同形态纳米碳酸钙制备及应用的研究进展

本文介绍了晶形控制技术,从不同形貌角度分别对球形、针状、链锁状、立方形、片状以及无定形纳米碳酸钙的制备与应用进行了阐述与分析,并对其广阔的发展前景作了展望.     

MBS核-壳粒子的内部结构对MBS/PVC光学性能的影响

以乳液聚合的方法合成了具有核-壳结构的MBS树脂。恒定MBS中M/B/S的比例为30/42/28,通过采用不同的引发体系及加料方式制备不同内部结构的橡胶粒子。将MBS树脂与聚氯乙烯（PVC）共混,研究了橡胶粒子的内部结构对共混物透光性的影响。用透射电子显微镜对共混物的形态进行了研究,MBS粒子分别具不同的包容物结构。研...     

不同晶化温度对ZSM-5分子筛结构和形貌的影响

以四丙基溴化铵（TPABr）为结构导向剂,采用水热法制备了ZSM-5分子筛。利用XRD、FT-IR及SEM等表征手段研究了不同晶化温度对样品结构、形貌和粒径大小的影响规律。当晶化温度由95℃升高至175℃,结晶度由48．3％提高到95．1％,产物粒径分布更为均匀。晶化温度为195℃时,结晶度减至79．7％,部分粒径增大且不规则。由此可见,通过升高晶化温度可以提高ZSM-5分子筛的结晶度和粒径的均匀性,但是过高温度会使分子筛发生溶解-再结晶过程,部分转化成SiO2。