Positional cloning and characterization reveal the role of a miRNA precursor gene ZmLRT in the regulation of lateral root number and drought tolerance in maize

Lateral roots play essential roles in drought tolerance in maize(Zea mays L.). However, the genetic basis for the variation in the number of lateral roots in maize remains elusive. Here, we identified a major quantitative trait locus(QTL),q LRT5-1, controlling lateral root number using a recombinant inbred population from a cross between the maize lines Zong3(with many lateral roots) and 87-1(with few lateral roots).Fine-mapping and functional analysis determined that the candidate gene for qLRT5-1,ZmLRT, expresses the primary transcript for the microRNA miR166a. ZmLRT was highly expressed in root tips and lateral root primordia,and knockout and overexpression of ZmLRT increased and decreased lateral root number,respectively. Compared with 87-1, the ZmLRT gene model of Zong3 lacked the second and third exons and contained a 14 bp deletion at the junction between the first exon and intron,which altered the splicing site. In addition,ZmLRT expression was significantly lower in Zong3 than in 87-1, which might be attributed to the insertions of a transposon and over large DNA fragments in the Zong3 ZmLRT promoter region. These mutations decreased the abundance of mature miR166a in Zong3, resulting in increased lateral roots at the seedling stage.Furthermore, miR166a post-transcriptionally repressed five development-related class-Ⅲ homeodomain-leucine zipper genes. Moreover,knockout of ZmLRT enhanced drought tolerance of maize seedlings. Our study furthers our understanding of the genetic basis of lateral root number variation in maize and highlights ZmLRT as a target for improving drought tolerance in maize.

关于椭圆曲线E(d^2)：y^2=x^3-d^2x的Artin Root Number的计算(英文)

作者给出了一类椭圆曲线Ed2:y2=x3-d2x的Artin Root Number的精确表达式,这里d=π1…πrω1…ωsq1…qt是一些互不相同的"标准"的高斯素数的乘积.这是在赵春来的相关结果的推广.

Correlation of Leaf and Root Senescence During Ripening in Dry Seeded and Transplanted Rice

Dry seeding is a resource-saving rice establishment method. With an equivalent yield, dry seeded flooded rice （DSR） has been considered as a replacement for traditional transplanted flooded rice （TFR）. However, the differences in leaf and root senescence during grain filling between DSR and TFR were seldom identified. In this study, the root length, root tip number and leaf senescence of rice varieties Huanghuazhan and Yangliangyou 6 during ripening were compared between DSR and TFR. Results showed that top three leaves in DSR had the characteristics of relatively lower SPAD value, lower N content and premature leaf senescence. In addition, both the total root length and total root tip number of DSR were significantly lower than those of TFR. In conclusion, premature and quick leaf senescence was related with inadequate root length and root tip number during ripening, which might result from the deficiency of nitrogen supply in DSR. Techniques on improving leaf nitrogen status and delaying the leaf senescence during grain-filling in DSR should be developed in future researches.

Effects of free-air CO_2 enrichment on adventitious root development of rice under low and normal soil nitrogen levels

Free air CO2 enrichment(FACE) and nitrogen(N) have marked effects on rice root growth,and numerical simulation can explain these effects. To further define the effects of FACE on root growth of rice, an experiment was performed, using the hybrid indica cultivar Xianyou63. The effects of increasing atmospheric CO2 concentration [CO2], 200 μmol mol-1higher than ambient, on the growth of rice adventitious roots were evaluated, with two levels of N: low(LN, 125 kg ha-1) and normal(NN, 250 kg ha-1). The results showed a significant increase in both adventitious root number(ARN) and adventitious root length(ARL) under FACE treatment. The application of nitrogen also increased ARN and ARL, but these increases were smaller than that under FACE treatment. On the basis of the FACE experiment, numerical models for rice adventitious root number and length were constructed with time as the driving factor. The models illustrated the dynamic development of rice adventitious root number and length after transplanting, regulated either by atmospheric [CO2] or by N application.The simulation result was supported by statistical tests comparing experimental data from different years, and the model yields realistic predictions of root growth. These results suggest that the models have strong predictive potential under conditions of atmospheric [CO2] rises in the future.

土壤水分含量对旱稻根系和土壤呼吸速率的影响

在池栽条件下比较研究了不同土壤水分含量处理(65%WHC、75%WHC、85%WHC、95%WHC和100%WHC,WHC代表田间最大持水量)对旱稻277土壤呼吸速率及根条数的影响。结果表明,土壤水分含量对旱稻土壤呼吸速率和根条数有显著影响。随着土壤水分含量的提高,土壤呼吸速率显著下降;随着旱稻生育期的推进,除100%WHC处理的土壤呼吸速率减小外,其余水分含量处理的土壤呼吸速率都呈升高趋势;随着土壤水分含量的增加,旱稻根条数逐渐降低,在分蘖前期处理间差异达到显著水平,随着生育期的推进,处理间的差异逐渐减小,且根条数与土壤呼吸速率呈显著正相关关系。土壤呼吸速率日变化在65%WHC、75%WHC和85%WHC处理下表现为逐渐增加后保持稳定,在95%WHC处理下表现为达最大值后逐渐下降,在100%WHC处理下表现为达最大值后略有下降,并一直保持在较低水平。土壤温度日变化在不同土壤水分含量下均呈现先升高再趋于平稳的变化趋势,以75%WHC水分处理下的温度最高,95%WHC和100%WHC水分处理下土壤温度较低。相关分析表明,不同水分含量处理条件下(100%WHC处理除外),土壤呼吸速率与土壤温度呈显著或极显著的二次抛物线关系,根条数与土壤呼吸速率呈显著的正相关关系。

On Some Properties of Digital Roots

Digital roots of numbers have several interesting properties, most of which are well-known. In this paper, our goal is to prove some lesser known results concerning the digital roots of powers of numbers in an arithmetic progression. We will also state some theorems concerning the digital roots of Fermat numbers and star numbers. We will conclude our paper by an interesting application.

Two New Iterated Maps for Numerical Nth Root Evaluation

In this paper we propose two original iterated maps to numerically approximate the nth root of a real number. Comparisons between the new maps and the famous Newton-Raphson method are carried out, including fixed point determination, stability analysis and measure of the mean convergence time, which is confirmed by our analytical convergence time model. Stability of solutions is confirmed by measuring the Lyapunov exponent over the parameter space of each map. A generalization of the second map is proposed, giving rise to a family of new maps to address the same problem. This work is developed within the language of discrete dynamical systems.

海南火龙果园土壤肥力与根结线虫数量调查

为了明确海南岛火龙果园土壤肥力状况和根结线虫危害情况,采集了海南岛68家火龙果园的土壤样品共204份,分析测定了土壤氮、磷、钾、钙、镁等矿质营养元素含量及根结线虫的数量,并采用模糊综合评判法对果园土壤综合肥力状况进行评价,分析了根结线虫数量与土壤养分状况的相关性。结果表明:海南岛火龙果园土壤pH为6.4,整体呈中性或弱酸性;有机质含量为19.9 g·kg^(-1),碱解氮含量为63.9 mg·kg^(-1),速效钾含量为95.8 mg·kg^(-1),均处于缺乏状态,而有效磷、交换性钙含量为丰富及以上等级,交换性镁处于中量水平;土壤pH与有机质、交换性钙、镁含量呈显著正相关,表明维持中性的pH水平有利于土壤有机质的积累,对钙、镁的有效性有重要意义;土壤有机质含量与碱解氮、有效磷、速效钾、交换性钙、镁含量呈显著正相关,说明土壤有机质的提高有助于提升土壤基础矿质养分的含量;各火龙果园根结线虫数量差异较大,其中,每100克干中土根结线虫2龄幼虫(J2)数量最多的可达736条,而较少的仅有14条;根结线虫发生轻重情况南北差异较大,整体上北部地区的火龙果园根结线虫数量低于南部地区;土壤pH、有机质、有效磷、交换性钙与根结线虫数量呈正相关。调查结果显示,海南岛火龙果园土壤综合肥力指数处于较高水平。

丁香酸对不同品种烟草苗期根系生长的影响

为探究最新发现的植物源生物硝化抑制剂丁香酸对烟草品种K326和云烟85苗期根系生长的影响,通过基质培养试验,设置0、10、25、50、100、200 μmol/L 6个丁香酸浓度,研究了不同浓度丁香酸在不同时间(3 d和5 d)对K326和云烟85主根伸长量和一级侧根发育的影响。结果表明:与对照(0 μmol/L)相比,25~100 μmol/L丁香酸能促进K326主根伸长,在3 d时促进率为13.33%~30.67%,在5 d时促进率降为8.54%~22.55%,最适浓度为50 μmol/L;10~50 μmol/L丁香酸促进云烟85主根伸长,在3 d时促进率为7.81%~18.75%,在5 d时促进率维持在4.10%~10.66%,最佳促进浓度25 μmol/L;丁香酸对两个烟草品种主根伸长的促进效果均为3 d优于5 d。在侧根发育方面,低浓度丁香酸能显著促进K326和云烟85一级侧根数,两个品种促进侧根发育的最适浓度均为25 μmol/L。相关性分析表明,丁香酸处理下两个烟草品种苗期的主根伸长变化率与侧根数变化率呈显著正相关。可见,适宜浓度的丁香酸对两个典型烟草品种苗期主根增长和侧根发育均为促进效应。生物硝化抑制剂丁香酸具有促进烟草根系生长的潜力,为研发烤烟新型专用肥提供了理论依据。

‘热研2号’柱花草对不同邻近植物的识别与生物响应差异

为明确‘热研2号’柱花草(Stylosanthes guianensis‘Reyan No.2’)对邻近植物的识别与生物响应对策,研究了其分别与自我、近亲、远亲和非亲4个亲缘关系组的10种植物伴生时的生长情况。结果表明:亲缘关系对‘热研2号’柱花草的株高和分枝数均值无显著影响,但近亲组伴生使其总生物量和地上生物量均值显著增加而根冠比均值显著减小(P<0.05),远亲和非亲组伴生使其根长、根冠比、生物量均值均显著降低而侧根数均值显著增加(P<0.05)。生长指标变化结合主成分分析表明:与‘热研21号’(S.guianensis‘Reyan No.21’)、‘热研24号’(S.guianensis‘Reyan No.24’)、‘热研5号’(S.guianensis‘Reyan No.5’)和鬼针草(Bidens pilosa)为邻株时,‘热研2号’柱花草的地上部生长显著增强,且程度依次减弱;与西卡柱花草(S.scabra)、细茎柱花草(S.gracilis)、蒺藜草(Cenchrus echinatus)、羽芒菊(Tridax procumbens)和大叶柱花草(S.grandifolia)为邻株时,其地上部和地下部生长均变差,且程度依次增强。说明‘热研2号’柱花草与近亲缘品种伴生时地上部生长相对较强,与远亲缘和非亲缘种伴生时地上、地下生长均减弱。

13个玉米品种萌发期耐旱性鉴定与筛选

种子萌发期的抗旱能力可在一定程度上反映该作物的耐旱性,种子萌发期是评价作物耐旱性的一个重要时期。为筛选出耐旱玉米品种,以清水作对照,用高渗溶液PEG-6000模拟干旱胁迫,对13个玉米品种进行发芽培养试验。结果表明:综合考虑发芽率、芽长、根长、须根数4个指标,以鑫禾528的抗旱性最强,其次为珍棒511和中科玉509。该结果可以有效反映其在后期生长过程中的抗旱性,为生产上选用抗旱品种提供参考依据。

锥形束CT测量成人上颌前磨牙根尖与上颌窦位置关系及其对即刻种植的影响

目的分析上颌前磨牙牙根与上颌窦空间位置关系,为该位点即刻种植时机、方案、术式及种植体选择等提供解剖依据。方法本研究已通过单位伦理委员会审查批准,并获得患者知情同意。收集2017年1月⁃2023年3月瑞华口腔门诊部就诊的264例患者(年龄20~65岁)口腔锥形束CT(cone beam CT,CBCT)影像,选取冠状面测量上颌前磨牙根尖到上颌窦下壁的最短距离,对牙根与上颌窦下壁的垂直关系分类,并就双侧、性别及不同年龄组进行比较。结果上颌前磨牙根尖至上颌窦下壁最短距离:上颌第一前磨牙单根型中位数为7.34 mm,双根型颊根中位数为7.80 mm,腭根中位数为7.36 mm;上颌第二前磨牙单根型中位数为2.56 mm,双根型中颊根中位数为1.73 mm,腭根中位数为1.23 mm。上颌第二前磨牙右侧单根型根尖至上颌窦下壁间最短距离在各年龄组间有统计学差异(P<0.05),20~29岁组最小(中位数1.52 mm),≥40岁组最大(中位数4.44 mm)。性别和左右侧对根尖到窦下壁距离的影响无统计学差异(P>0.05)。上颌前磨牙根尖与上颌窦垂直关系中,根尖不与上颌窦下壁接触的情况占比最高,垂直关系分类在单根型和双根型间无统计学差异(P>0.05)。结论上颌第一前磨牙根方大多可为即刻种植提供足够高度骨量,较易实现即刻种植;上颌第二前磨牙根方骨量不足常见,需充分利用拔牙窝骨壁或窦底皮质骨实现初期稳定性;根尖与窦下壁垂直关系分型分布受年龄及牙位影响,青年组较其他年龄组更易出现骨高度不足,需谨慎选择即刻种植适应证;牙根数量对牙根与上颌窦垂直关系影响不大,双根型因牙根直径小及根间骨性分隔,可为即刻种植提供更多骨支持。

有限循环群上奇素数次方根态射的个数

设G为m阶有限循环群,m>1,φ:G→G为群同态。若φ^(k)=1_(G),1_(G)为恒等态射,k为正整数,称φ为G的k次方根态射,求出当k为奇素数时G的k次方根态射的个数。

激素不同浓度在一定时间下对白牛槭嫩枝扦插生根的影响

采用激素NAA、IBA,浓度0、500、1 000、1 500 mg/L,时间0、5、10、15 min,以2年生白牛槭嫩枝作为试验材料研究其扦插技术,探讨激素和浓度在一定时间下对白牛槭嫩枝扦插生根的影响。试验中发现9号处理生根数最多,用相同浓度IBA1 000 mg/L+NAA1 000 mg/L速蘸5 min,白牛槭生根数最大值85(条),比6号处理在相同浓度IBA500 mg/L+NAA500 mg/L作用下速蘸5 min,生根数最小值3.33(条)大2 452.5%,比白牛槭14个处理根数平均值25.53(条)大232.9%;3号处理根长最长,用不同浓度IBA500 mg/L+NAA1 000 mg/L速蘸10 min,白牛槭根长最大值11.03 cm,比14号处理在不同浓度IBA1 000 mg/L+NAA500 mg/L速蘸5 min,根长最小值1.8 cm大512.7%,比14个处理根长平均值7大57.57%;2号处理根径的粗度最大,用不同浓度IBA0 mg/L+NAA1 000 mg/L速蘸10 min,白牛槭根径最大值1.78 mm,比14号处理在不同浓度IBA1 000 mg/L+NAA500 mg/L速蘸10 min,根径最小值0.49 mm大263.3%,比14个处理根径平均值0.67 mm大165.7%。因此,9号处理在相同激素浓度和相同时间、3号处理和2号处理在不同激素浓度和不同时间处理下,白牛槭嫩枝扦插生根数、生根长和生根茎的粗度数值都是最大(85条、11.03 cm、1.78 mm),生长表现最好。

“低温诱导植物细胞染色体数目的变化”实验的探索

参照人教版“低温诱导植物细胞染色体数目的变化”实验步骤,设计常温对照组,以及改变低温诱导的时长等一系列实验。研究发现,低温诱导后,大蒜根尖有丝分裂前中后各时期细胞中的染色体数目虽然未能准确计数,但与常温对照组相比明显增多;低温诱导72 h后再恢复常温处理24 h,染色体数目增加的细胞分裂相较多,优于单一低温处理。

Small Modular Solutions to Fermat’s Last Theorem

The proof by Andrew Wiles of Fermat’s Last Theorem in 1995 resolved the existence question for non-trivial solutions in integers x,y,zto the equation xn+yn=znfor n>2. There are none. Surprisingly, there are infinitely many solutions if the problem is recast in terms of modular arithmetic. Over a hundred years ago Issai Schur was able to show that for any n there is always a sufficiently large prime p0such that for all primes p≥p0the congruence xn+yn≡zn(modp)has a non-trivial solution. Schur’s argument wasnon-constructive, and there is no systematic method available at present to construct specific examples for small primes. We offer a simple method for constructing all possible solutions to a large class of congruences of this type.

林下园参栽培技术及产量研究

为研究在保证不破坏林地环境的前提下,将园参栽培技术应用于林下参栽培,通过试验对参苗移栽与管理技术进行分析,包括选择最佳的移栽时间、控制适宜的覆土厚度以及林下园参的施肥、除草等管理措施,进而优化林下园参栽培与管理技术。结果表明:秋季移栽,较春栽4月上旬和中下旬林下园参的株高、根状茎直径、根状茎鲜重分别高12.57%、14.01%、18.75%和4.12%、3.39%、3.32%;移栽覆土厚度3~5 cm,1年生林下园参的株高、根状茎直径、根状茎鲜重较覆土≥5 cm和≤3 cm分别高23.16%、35.23%、35.81%和13.94%、29.35%、22.32%;施肥措施为生物菌肥最佳;对林下园参进行人工除草3次较1次人工除草和不除草的5年生林下园参株高、根状茎直径、根状茎鲜重分别高22.87%、34.13%、25.58%和82.06%、52.25%、102.72%;林下参至收获年即15 a时667 m2仅为3570株,而林下园参的收获年即6 a时667 m2保苗数达到25630株;林下园参5 a平均根茎干重比林下参10 a提高了64.9%。

硝酸盐供应对玉米侧根生长的影响

以两个玉米(Zea mays L.)自交系478和Wu312 为研究材料,采用琼脂培养方法,研究不同浓度NO3- 对侧根生长的影响。结果表明,在外部浓度0.01-1.0 mmol／L范围内,NO3-供应能显著增加侧根的长度及根 生物量。但当NO3-供应超过1.0 mmol/L后,侧根长度 开始下降。当NO3-供应分别在超过5.0(Wu312)与10 (478)mmol／L后,侧根密度显著下降。在10 mmol／L NO3-下,Wu312的侧根生长几乎完全被抑制。而478在 20 mmol／L时,侧根密度仍可达到其最大值的30％(主 根)-50％(胚根)。植株地上部全氮及硝酸盐含量随 NO3-供应的增加而升高,二者与侧根长度、侧根密度 及冠根比的数学函数关系相同。

4种生长调节剂对三角梅扦插生根的影响

2009年在昆明市松花坝苗圃地,以三角梅4年生健壮母树上1年生枝条为插穗,利用不同浓度(50 mg/L、100 mg/L、150 mg/L、200 mg/L)的4种生长调节剂(IAA、IBA、ABT1、NAA)分别处理三角梅插穗后进行随机区组扦插试验,调查各生长指标,并进行方差分析。结果表明,相同条件下,不同生长调节剂的不同浓度水平对三角梅插穗的影响不同,以IAA 50 mg/L浸泡24 h的插穗,扦插生根效果最好,平均生根数为18根,平均根长为3.95 cm,生根率为91.67%;用100 mg/L的IAA处理的插穗,扦插生根效果次之。4种生长调节剂处理插穗的生根效果依次为IAA、IBA、ABT1、NAA,均显著优于对照。

不同生根剂对四种核桃扦插成活率和根数的影响

【目的】研究不同浓度的萘乙酸(NAA)、吲哚丁酸(IBA)和生根粉(ABT)对四种核桃品种(温185、新丰、新早丰、新新2号)扦插成活率和生根数的影响。【方法】以纯水作为对照,使用浓度为200、300、400 mg/L的萘乙酸(NAA)、吲哚丁酸(IBA)和生根粉(ABT)溶液处理温185、新丰、新早丰、新新2号的扦插枝条,在细沙中培育45 d催根后,统计每个处理的根数,并计算其平均成活率。【结果】在萘乙酸处理中以300 mg/L的平均成活率72.5%、平均根数9.25,比纯水对照高5%和2条。400 mg/L的吲哚丁酸(IBA)处理中成活率72.5%、平均根数9.25,比纯水对照高5%和2条。300 mg/L的生根粉中平均成活率77.5%、平均根数11.25,比纯水对照高10%和4条。400 mg/L的萘乙酸和200 mg/L的吲哚丁酸平均成活率62.5%、平均生根数7.5,比纯水对照低5%。【结论】300 mg/L的生根粉对温185、新丰、新早丰、新新2号核桃生根效果最好,比较适合核桃扦插栽培。萘乙酸400 mg/L和吲哚丁酸200 mg/L的催根效果不佳,在生产上要谨慎使用。