富钾基因型烤烟的钾积累及根系生理特性

采用室内营养液培养(钾浓度为3 mmol L^-1)的方法, 以富钾基因型烤烟农大202与2个一般型品种净叶黄、NC89为材料, 研究富钾基因型烤烟钾积累及根系生理特性。结果表明, 3个烤烟品种根和茎中钾积累量无显著差异, 但农大202的叶片钾积累量、根系活力和根系总活力、根系H⁺分泌量、根系阳离子交换量(CEC)、根系可溶性蛋白含量和ATPase活性均极显著高于另两个品种。净叶黄、NC89间除根系活力和根系H⁺分泌量差异达显著水平外, 其他根系生理特性差异均不显著。根系钾吸收动力学参数结果显示,农大202苗期钾离子最大吸收速率(V_max)较高而米氏常数(K_m)和钾离子吸收临界浓度(C_min)较低, 而旺长期的V_max、K_m及C_min均较高, 说明其根系具有较高的钾吸收速率, 但旺长期后耐低钾能力较差。     

CuFe2O4纳米粒子增敏Luminol-EDTA化学发光体系研究及应用

基于CuFe₂O₄纳米粒子能显著增强Luminol-EDTA体系的发光,首次建立了Luminol-EDTA-CuFe₂O₄ NPs化学发光新体系。紫外吸收光谱和化学发光光谱表明纳米CuFe₂O₄注入Luminol-EDTA体系后,未生成新发光物质,结合纳米CuFe₂O₄的特性,提出了CuFe₂O₄ NPs参与Luminol-EDTA体系可能的发光机理。研究发现芦丁能抑制Luminol-EDTA-CuFe₂O₄ NPs体系的化学发光,结合流动注射技术,将此化学发光体系应用于芦丁片中芦丁含量的测定。在优化实验条件下,芦丁浓度在2×10^-8~2×10^-5 mol/L范围内芦丁浓度的对数和相对化学发光值呈线性,芦丁浓度检出限（LOD）为1.21×10^-9 mol/L。将本方法应用于芦丁片中的芦丁含量测定,回收率为97%~102%,RSD为2.54%（c=1×10^-7mol/L,n=11）。     

玉米籽粒赖氨酸含量的遗传及其与产量的关系分析

用5个不同基础群体的15个自选系作母本, 5个不同优势群的测验系作父本, 采用NCII交配设计配成75个杂交组合, 经1年2点田间试验, 用近红外光谱仪测定了亲本及其杂交种F₁和F₂籽粒的赖氨酸含量, 并用三倍体种子胚乳-细胞质-母体效应模型对赖氨酸含量进行遗传分析。结果表明, 玉米籽粒赖氨酸含量除受种子、母体效应和细胞质3套遗传体系共同控制之外, 还不同程度受环境因素的影响, 遗传主效应方差V_G (V_G=V_A+V_D+V_C+V_Am+V_Dm)占总遗传方差(V_G+V_GE)的76.3%, 其中, 种子效应方差(V_A+V_D)、细胞质效应方差(V_C)和母体效应方差(V_Am+V_Dm)分别占24.6%、19.7%和55.7%;赖氨酸含量以母体遗传力为主(h²_m=40.98%), 其次为种子遗传力(h²_o=17.86%), 而细胞质遗传力较低(h²_c=14.29%)。同时发现籽粒赖氨酸含量与产量之间不存在明显相关(r = –0.027)。因此, 在高赖氨酸育种中, 必须重视高值亲本尤其是母本的选择以及不同优势类群间的广泛组配, 从变异广泛的基础材料中对赖氨酸含量和籽粒产量同时进行选择和改良是可能的。     

非线性Mohr-Coulomb破坏准则下边坡可靠度上限

传统边坡可靠度分析往往在岩土参数服从线性Mohr-Coulomb（简称线性M-C）破坏准则的假设条件下进行,并且常常采用极限平衡法或有限元法计算安全系数。然而,岩土介质破坏准则具有一定的非线性。为能更加实际地描述岩土破坏机理和得到严格精确的解,基于非线性Mohr-Coulomb（简称非线性M-C）破坏准则,结合极限分析上限法和蒙特卡洛法,进行边坡可靠度上限分析。当非线性参数m=1时,与等效的线性M-C破坏准则进行对比计算,验证了方法的可行性。同时,将初始粘聚力、内摩擦角arctan（c₀/σ_t）和非线性参数作为随机变量且服从截断正态分布,进行了参数变异性和敏感性影响分析。研究表明：非线性M-C破坏准则下,边坡可靠度随初始粘聚力、内摩擦角arctan（c₀/σ_t）和非线性参数变异性的增大而减小;边坡可靠度随初始粘聚力和内摩擦角arctan（c₀/σ_t）的增大而增大,随非线性参数的增大而减小。     

转2-Cys Prx基因烟草抗氧化酶和PSII电子传递对盐和光胁迫的响应

以转2-Cys Peroxiredoxins (2-Cys Prx)基因的烟草(Nicotiana tabacum)为材料,非转基因烟草为对照,调查盐和光胁迫对转基因烟草幼苗叶片抗氧化酶和叶绿素荧光特性的影响,揭示2-Cys Prx基因在植物抗逆方面的功能。结果表明,弱光(200 μmol m^–2 s^–1)下,随着盐浓度增大,转基因烟草和对照的SOD活性皆增加,APX活性变化不大,H₂O₂含量稍有升高;强光(1000 μmol m^–2 s^–1)下,随着盐浓度增大,转基因烟草SOD活性增强,APX活性下降,H₂O₂含量增加缓慢,而对照的H₂O₂含量迅速升高,转基因烟草叶片的PSII电子传递速率(ETR)、最大光化学效率(F_v/F_m)和实际光化学效率(Ф_PSII)均高于对照,而且PSII电子受体侧的受抑制程度明显低于对照。结果暗示在强光和盐胁迫使APX活性降低的情况下,2-Cys Prx可有效清除细胞中过量H₂O₂,增强光合电子传递链的稳定性,特别是PSII电子受体侧的电子传递,有效减轻盐和高光胁迫引起的PSII光抑制。     

棉花黄萎病生防芽孢杆菌 Z-5 菌株发酵培养基的优 化简

 在农用微生物菌剂中芽孢杆菌菌剂产品多采用芽孢作为有效成分,因此产芽孢条件的优化对棉花黄萎病生防细菌的工业生产有着重要意义。本文通过单因素试验分析了8种碳源、8种氮源和6种无机盐对Bacillus malacitensis Z-5菌株芽孢产量的影响,采用Plackett-Burman试验设计确定了影响芽孢产量的主要因素,用最陡爬坡路径逼近最大响应区域,利用Box-Behnken试验设计及响应面分析法确定主要影响因素的最佳条件。结果表明,单因素试验筛选出3种碳源（玉米粉、麸皮、葡萄糖）、3种氮源（豆饼粉、花生饼粉、酵母粉）和2种无机盐（MnSO₄·H₂O、CaCl₂）;Plackett-Burman试验确定Z-5菌株生产芽孢最适碳源、无机盐和氮源分别为玉米粉、MnSO₄·H₂O和豆饼粉,最陡爬坡路径法获得此3种因子的最适浓度范围为：玉米粉1.0%~2.0%、MnSO4·H2O 0.05%~0.09%、豆饼粉为1.0%~2.0%。响应面法得到芽孢产量与玉米粉、MnSO4·H2O和豆饼粉含量的回归方程。最终确定优化培养基组合为玉米粉1.66%、豆饼粉1.30%、MnSO₄·H₂O 0.07%、NaH₂PO₄·2H₂O 0.2%、Na₂HPO₄·2H₂O 0.4%,优化后芽孢产量达到1.9⁷×10⁹ mL^-1,与理论值基本相符。     

盐胁迫条件下外源Ca2+对蚕豆气孔运动及质膜K+通道的调控

研究了Ca²⁺ 对NaCl胁迫下蚕豆气孔运动及质膜K+通道的影响。结果表明,100 mmol L^-1 NaCl可明显诱导气孔开放,该现象可被10 mmol L^-1 CaCl₂ 显著抑制。为探讨盐胁迫下Ca²⁺对K⁺和Na⁺跨膜运输的调控机制,我们利用膜片钳技术记录全细胞K⁺ 电流发现,在100 mmol L^-1 NaCl胁迫下,加入10 mmol L^-1 CaCl₂胞外处理,显著抑制质膜K+内向及外向通道电流,这种抑制可被1 mmol L^-1 La³⁺ (Ca²⁺通道抑制剂)缓解。非盐胁迫下,10 mmol L^-1 CaCl₂ 胞外处理也能显著抑制质膜内向K⁺通道,但明显激活其外向通道,加入1 mmol L^-1 La³⁺并不能被缓解。用H₂O₂专一的荧光探针二氯荧光素二乙酸酯(H2DCF-DA)单细胞分析保卫细胞内H₂O₂含量变化显示,在100 mmol L^-1 NaCl盐胁迫下,10 mmol L^-1 CaCl₂ 处理明显诱导H₂O₂在保卫细胞中积累;100 mmol L^-1 NaCl和10 mmol L^-1 CaCl₂单独处理并不能诱导H₂O₂积累。推测Ca²⁺在盐胁迫下可能先诱导H₂O₂在胞内积累,进而激活质膜Ca²⁺通道,迅速提高胞内Ca²⁺浓度以抑制Na⁺通过质膜K⁺通道跨膜内流,同时调节Na⁺外流,两种效应共同作用促使气孔关闭,减少盐胁迫下水分的过度散失。上述结果将为Ca²⁺调控作物抗盐机制研究提供新的思路。     

棉株果枝部位、温光复合因子及施氮量对纤维伸长的影响

以杂交棉(科棉1号)和常规棉(美棉33B)品种为材料,设置异地分期播种和施氮量试验,使棉株不同果枝部位棉铃处于相同环境条件下或相同果枝部位棉铃处于不同环境条件下,研究棉株果枝部位、温光复合因子及施氮量对纤维伸长的影响。结果表明, 在相同环境条件下,棉株中部果枝铃的纤维长度虽稍高于其他部位,但纤维伸长动态变化及最终纤维长度在不同果枝部位间的差异均未达显著水平。棉纤维伸长发育期的累积辐热积PTP可综合温光复合因子的效应,其与棉纤维最大伸长速率V_max呈极显著线性正相关,与纤维快速伸长持续期T呈极显著线性负相关,与棉纤维长度理论最大值Len_m呈二次曲线函数关系,可以作为表征棉纤维伸长发育温光复合因子的指标。当棉纤维伸长发育期内PTP在335 MJm^–2左右时,Len_m最大(科棉1号、美棉33B分别为30.94、30.31 mm),V_max在1.3 mm d^–1左右,T在16 d左右。氮素水平与温光复合因子对纤维长度的影响存在补偿效应,随施氮量的增加,棉纤维长度达到最大值时对应的PTP减小。当棉纤维伸长发育期内PTP达到240 MJm^–2时(科棉1号、美棉33B分别为237.6、241.6 MJm^–2),240 kg N hm^–2施氮量下的棉铃对位叶叶氮浓度(N_A)更适宜棉纤维伸长;PTP低于此值时,增加施氮量(480 kg N hm^–2)可减小因累积辐热积降低而造成的棉纤维长度缩短的幅度。     

我国玉米自交系叶片保绿性及其与产量的关系

选用我国75个常用不同基因型玉米自交系,对其叶片保绿性参数进行了定点动态测定。结果表明,不同自交系抽丝后叶片保绿度的变化均符合方程y = ae^b-cx/ (1+e^b-cx),成熟期的绿叶数、成熟期叶绿素含量和相对绿叶面积平均衰减速率(V_m)可作为区分玉米保绿型与非保绿型的关键指标。按照Hiechical聚类分析方法,筛选出12个保绿型自交系,其成熟期相对绿叶面积在60%以上,其V_m平均值为0.687% d^-1,在生长季内相对绿叶面积无大幅度衰减,成熟期绿叶数多,叶绿素含量较高;其余63个为非保绿型自交系,还可分为植株叶片衰老较快型与植株叶片衰老较慢型两个亚类。不同自交系抽丝后叶片保绿性与叶面积持续期、单株产量均呈正相关。保绿型的叶面积持续期和单株产量比非保绿型分别高20.02%~23.87%和50.44%~59.38%;与非保绿型自交系相比,保绿型在籽粒灌浆期绿叶面积大,叶绿素含量高,群体光合速率高,光合作用时间长,因而生物产量较高。     

玉米和高粱用于碳同化和光呼吸的电子效率估算

为了探讨C₄植物碳同化和光呼吸的电子效率,运用Li-6400光合仪同时测定玉米和高粱在30℃和380 μmol CO₂ mol^-1下叶片的气体交换和叶绿素荧光,结果表明,直角双曲线修正模型可较好地拟合所测的光响应曲线和快速光曲线,其拟合值与实测值较为一致。在此基础上算得玉米和高粱在光呼吸条件下参与碳同化的电子流分别为198.60 μmol m^-2 s^-1和178.00 μmol m^-2 s^-1,所占比率分别为75.34%和74.81%;参与光呼吸的电子流分别为7.04 μmol m^-2 s^-1和7.84 μmol m^-2 s^-1,所占比率分别为2.67%和3.29%。而根据Valentini和Epron的方法算得玉米和高粱碳同化的电子流分别为210.45 μmol m^-2 s^-1和188.54 μmol m^-2 s^-1,所占比例分别为82.68%和79.24%;参与光呼吸的电子流则分别为45.67 μmol m^-2 s^-1和49.40 μmol m^-2 s^-1,所占比率分别为17.32%和20.76%。以前法研究表明,玉米和高粱在光呼吸条件下,来自PSII的电子除流向光呼吸和碳还原外,还存在其他消耗电子的途径,证明其他消耗电子的途径并不能被忽略或其他途径所消耗电子的量并不是常数。后法过高地估算了玉米和高粱叶片中来自PSII的电子用于光呼吸的消耗量。两法的结果相差6倍左右。这对重新评估光呼吸在植物的光保护中所起的作用提供了理论依据。     

Utilization of deletions to localize a gene for resistance to the cereal cyst nematode, Heterodera avenue, on an Aegilops ventricosa chromosome

A previous RFLP analysis showed that the Aegilops ventricosa chromosome 6M^V which compensates for the absence of 6D in 6M^V (6D) wheat substitution lines was a 2/6 translocated chromosome, either 2S–6S.6L or 2S–6L.6S. The distal part of its long arm consists of a translocated segment belonging to homoeologous group 2. Chromosome 6M^V carries a gene(s) for resistance to cereal cyst nematode. In order to define the part of 6M^V (2S or 6S or 6L) involved in this resistance, addition lines with a 6M^V deleted either for its short arm or for the distal part of its long arm were evaluated. It was shown that the gene(s) is carried by the group 2 translocated segment. The hypothesis that the gene(s) could be allelic to Cre2, another gene conferring resistance to the nematode introduced into the wheat complement from Ae. ventricosa is discussed.     

氧气高炉工艺研究进展及新炉型设计

从氧气高炉的数学模型、实验室实验以及工业试验角度系统分析了氧气高炉工艺的发展现状及趋势,同时讨论了氧气高炉炉型的设计依据。论述了氧气高炉的静态工艺模型研究需要计算合适的直接还原度和热空区温度,同时应考虑氧气高炉工况下生产率的变化、热损失的变化、风口煤粉的喷吹上限以及N₂的循环积累等问题。指出了多维动力学模型和多目标优化模型中尚需解决的问题,以及氧气高炉数学模型的主要发展方向。结合文献研究中的氧气高炉特点,从炉身高度设计、炉腹角和炉身角设计以及风口设计3方面综述了氧气高炉炉型设计的变化规律。     

Root peroxidases and Rhizobium, Bradyrhizobium nodulation affinities of Phaseolus vulgaris L. and P. acutifolius A. Gray congruity backcross populations

Four parents [P. acutifolius var.acutifolius (A₁₉), P. a.var. latifolius `Serowi' (A<sub>9</sub>),P. a. var. latifolius(A<sub>10</sub>), and P. vulgaris `Red Cloud' kidney (V₁)] were used to create six interspecific recurrent and congruity backcross pedigrees (V₁ × A₉, A₉ × V₁, V₁ × A₁₀, A₁₀ × V₁, V₁ × A₁₉, A₁₉ × V₁) for evaluation of Rhizobium, Bradyrhizobium nodulation affinities and root peroxidase banding patterns. Most primary hybrids nodulated with all Rhizobium, Bradyrhizobium strains, while recurrent generations nodulated with strains of the recurrent parent, suggesting a number of independent loci and random assortment for strain-specific nodulation. A proximity matrix of nodulation phenotypes produced a cluster with V₁, two recurrent and two congruity backcross hybrids with V₁ as the cytoplasmic parent; a separate cluster with all primary interspecific and balanced, congruity backcross hybrids. A₉ and A₁₀were clustered the farthest away from V₁. Root peroxidase zymograms of primary hybrids were the summation of the parents and controlled by independent loci. Advanced hybrids exhibited new root peroxidases, matching those found for otherPhaseolus spp., including ancestralP. coccineus. A proximity matrix of root peroxidase phenotypes produced a cluster with only A₉ ³V₁F₁, a cluster containing only A₁₉ ³V₁ F₂, and a large cluster with all P. acutifoliusparents and hybrids with P. acutifolius as the cytoplasmic parent in balanced hybrids or the majority parent in unbalanced hybrids. Estimation of genetic distances showed primary, interspecific hybrids to be more closely related with the cytoplasmic parent. Recurrent and congruity backcross generations varied in genetic distances between each respective parent. This is the first report of congruity backcrossing creating hybrids with biochemical traits of nonparental species. This revised version was published online in August 2006 with corrections to the Cover Date.     

尿素及秸秆添加对华中地区茶园土壤CO_2和N_2O排放的影响

为了明确尿素和秸秆添加对茶园土壤CO_2和N2O排放的影响,为茶园合理施肥提供理论依据,本研究在室内培养条件下,以华中地区红壤丘陵区茶园土壤为对象,运用静态培养系统研究方法,研究该土壤在尿素输入和作物秸秆添加后CO_2和N_2O的排放特征。培养试验共设置对照、尿素、作物秸秆和尿素+作物秸秆4种处理。结果表明:不同处理下华中地区茶园土壤CO_2和N_2O排放呈显著差异。作物秸秆添加显著提高茶园土壤CO_2的排放,作物秸秆和作物秸秆+尿素处理分别是对照的5.57和4.99倍。尿素输入显著促进茶园土壤N_2O的排放,而秸秆添加却降低N_2O的排放。对照和添加尿素处理土壤N_2O排放通量与铵态氮含量呈显著正相关关系。无秸秆添加处理土壤N_2O排放通量与硝态氮含量呈显著的相关性,而添加秸秆处理二者无显著相关关系。土壤可溶性有机碳含量对CO_2排放有显著影响,二者之间呈极显著线性正相关关系。     

Heterosis and heritability in crosses among Asian and Ethiopian parents of hot pepper genotypes

Hot pepper is the most important worldwide grown and consumed spice and vegetable crop. Though hybrid breeding has been proposed for genetic improvement in the crop, but there is lack of information on heterosis in crosses among crop genotypes in Ethiopia. Twelve genotypes (nine Asian and three Ethiopian parents) of hot pepper were crossed in 2003 cropping season in a half-diallel fashion to fit Griffing’s fixed effect model analysis. An open field experiment was conducted in 2004/2005 to investigate heterosis for fourteen traits in 66 F₁ hybrids grown together with their 12 selfed parents. Highly significant genotypic differences were observed for all the traits except for leaf area. Variance component due to specific combining ability (dominance) were larger than that due to general combining ability (additive) for each of the studied traits with few exceptions. Broad sense heritability (H _b²) for fruit traits were more than 60% and with wide gap from narrow sense heritability (h _n²) for most of the important traits like number of fruit per plant (H _b² = 88.3% and h _n² = 46.0%), days to maturity (H _b² = 87.2% and h _n² = 23.1%) and dry fruit yield per plant (H _b² = 72.6% and h _n² = 14.6%). Maximum heterosis over mid-parent and better-parent, and economic superiority of hybrid over standard check were recorded, respectively for dry fruit yield per plant (163.8, 161.8 and 92.1%), number of fruits per plant (104.4, 79.6 and 136.4%) and days to maturity (−29.8, −31.5 and −23.6%). These observations suggested a possibility of utilizing dominance genetic potentiality available in diverse genotypes of the crop by heterosis breeding for improving hot pepper to the extent of better economic return compared to the current commercial cultivar under production in the country. Low narrow sense versus very high broad sense heritability for days to maturity and dry fruit yield per plant could be a sign for achievability of earliness and high fruit yield using heterosis in hot pepper. The maximum heterobeltiosis were recorded either from F₁s obtained from Ethiopian and Asian crosses or from within Asian crosses, suggesting the possibility of maximizing heterosis by considering genetically diverse parental genotypes. The manifestation of highest heterosis in hybrids from among Asian lines indicated existence of genetic diversity among Asian genotypes and the potentiality for improvement of hot pepper using genotypes from different regions of the world along with elite inbred lines from local cultivars.     

玉米热激转录因子基因ZmHSF-Like对逆境胁迫响应的信号途径

在前期对玉米热激转录因子基因ZmHSF-Like克隆、表达特性和亚细胞定位分析的基础上,对基因响应不同逆境胁迫的信号途径进行了研究。结果显示,H₂O₂处理能显著上调ZmHSF-Like基因的表达,42℃热激上调ZmHSF-Like基因的表达依赖于H₂O₂的存在,ABA上调基因表达部分依赖于H₂O₂的存在,而PEG-6000诱导基因表达不依赖于H₂O₂;外源Ca²⁺处理也能上调ZmHSF-Like基因表达,而螯合胞外钙离子并阻断其内流并不能降低上述逆境胁迫诱导的ZmHSF-Like基因的表达水平。表明ZmHSF-Like基因通过H₂O₂信号途径实现对热激和ABA胁迫的响应。在H₂O₂处理过程中,热激蛋白基因HSP704的表达与ZmHSF-Like基因的表达同步,可能是该途径中ZmHSF-Like结合的下游热激蛋白。单独钙离子诱导处理,热激蛋白基因HSP701、HSP702和HSPeu701的表达均与ZmHSF-Like基因的表达同步,可能是ZmHSF-Like基因响应Ca²⁺反应的下游结合蛋白。ZmHSF-Like通过与下游不同热激蛋白的结合实现对不同逆境胁迫的响应。     

Root Growth Inhibition and Lignification Induced by Salt Stress in Soybean

Salt stress was evaluated on root growth, enzyme activities (phenylalanine ammonia‐lyase or PAL and soluble plus cell wall‐bound peroxidase or POD), hydrogen peroxide (H₂O₂) production, total phenolic content and lignin content and composition in soybean (Glycine max L. Merrill) roots. Three‐day‐old seedlings were cultivated in half‐strength Hoagland’s solution (pH 6.0), with or without addition of 50–200 mm of NaCl, into a growth chamber (25 °C, 12/12 h light/dark photoperiod, irradiance of 280 μmol m^?2 s^?1) for 24 h. In general, root length and fresh and dry weights decreased after NaCl treatment. PAL activity decreased, soluble and cell wall‐bound POD activities increased, and H₂O₂ content significantly decreased after NaCl exposure. Consequently, total phenolic and lignin contents and p‐hydroxyphenyl (H) and syringyl (S) monomers of lignin increased in NaCl‐treated roots. Altogether, these results suggest that the effects caused by NaCl may be owing to the enhanced lignin production that solidifies the cell wall and restricts root growth.     

Characterization of a set of common wheat–Hordeum chilense chromosome 7Hch introgression lines and its potential use in research on grain quality traits

Chromosome 7H^ch from Hordeum chilense has potential for improving seed carotenoid content in wheat as it carries a Phytoene synthase 1 (Psy1) gene, which has a major role in this trait. Structural changes in chromosome 7H^ch were obtained in common wheat background by crossing the wheat disomic substitution line 7H^ch(7D) with a disomic addition line carrying chromosome 2C^c from Aegilops cylindrica in common wheat cv. ‘Chinese Spring’. Rearranged 7H^ch chromosomes were cytologically characterized by FISH. A set of 24 molecular markers and the Psy1 gene were used to identify the H. chilense chromosome segments involved in the introgressions. Six structural rearrangements of chromosome 7H^ch were identified. They included three homozygous wheat–H. chilense centromeric translocations, one involving the 7H^chS arm (T‐7H^chS·A/B) and two involving the 7H^chL arm (T1‐7H^chL·A/B and T2‐7H^chL·A/B). In addition, one 7H^chS arm deletion, one 7H^chL·7H^chL isochromosome and one 7H^chS telosome were obtained in hemizygous condition. These genetic stocks will be useful for studying the effect of chromosome 7H^ch on wheat flour colour.     

Inheritance of leaf hairiness in Gossypium hirsutum L. cotton and its relationship with jassid resistance

Summary Two pairs of genes indicated by H ^P ₁ and H ^A ₂ appear to play a part in the genetic control of pubescence of leaves in the crosses of Pak51 x Empire Red leaf, L11 x Empire Red leaf, AC134 x Empire Red leaf, AC134 x Acala 1517D and L11 x Acala 1517 D. H ^P ₁ seems to induce hair of sufficient length and density and is completely dominant to h ^p ₁.H ^A ₂ allele, seems to induce hairiness but to a smaller degree. It acts additivily to H ^P ₁ giving profusely hairy plants. H ^P ₁ gene is present in the local varieties Pak51, L11 and AC134 producing hair of such length and density as to confer jassid resistance in them. Compared with these, the exotic types viz., Empire Red leaf and Acala 1517D possess H ^A ₂ giving sparsely hairy plants.The exotic variety Deltapine Smooth leaf possesses another gene, E ^A, which displays an epistatic effect on H ^A ₂ gene. The gene E ^A has only a minor effect on the H ^P ₁.Apart from this, the presence of certain intensifying or modifying genes seem to affect the density and length of hair resulting in deviations even in individual groups.M. Sc. Student, Professor and Head, and Reader, respectively of the Dept. of Plant Breeding and Genetics.     

多胺氧化酶(PAO)调控光诱导玉米中胚轴伸长的生理机制

以长中胚轴玉米自交系PH4CV为材料,在黑暗和光照两种处理条件下研究了玉米中胚轴长度与多胺氧化酶(Polyamine Oxidase, PAO)活性、H₂O₂含量、过氧化物酶(peroxidase, POD)活性及木质素含量的关系。通过添加5 mmolL^-1 PAO抑制剂2-羟乙基肼(2-hydroxyethylhydrazine, 2-HEH)和5 mmolL^-1 H₂O₂清除剂N,N’-二甲基硫脲(N,N’-Dimethylthiourea, DMTU)及组织化学染色,研究了影响中胚轴伸长的H₂O₂来源及其积累部位。采用实时荧光定量PCR(qRT-PCR)方法,探究了光对ZmPAO基因表达的影响。结果表明,光照处理显著抑制了玉米中胚轴的伸长,同时显著增加该部位的PAO活性、H₂O₂含量、POD活性及木质素含量。相关性分析表明,玉米中胚轴长度与PAO活性、H₂O₂含量和木质素含量呈极显著负相关,与POD活性呈显著负相关;PAO活性与H₂O₂含量、POD活性和木质素含量均呈正相关。外源PAO抑制剂和H₂O₂清除剂处理试验,玉米中胚轴表皮纵切面细胞长度显微观察及中胚轴H₂O₂组织化学染色表明,PAO氧化分解多胺(Polyamines, PAs)产生的H₂O₂参与了中胚轴细胞伸长的生理调控,从而抑制了中胚轴的伸长。表达分析表明,ZmPAO基因在黑暗环境下的表达量相对稳定,光刺激0.5 h后表达量迅速升高,3 h后达到最大值,随后逐渐下降,10 h后趋于稳定。本研究表明,PAO在接受光刺激后活性升高,氧化分解PAs产生H₂O₂,从而诱导POD氧化胞壁的单木质醇并聚合为木质素,使细胞壁硬化,造成细胞伸长受阻。研究结果为进一步探讨PAO活性调控光诱导玉米中胚轴伸长的生理机制和阐明玉米中胚轴对光逆境的响应机理提供了理论依据。