鲜食番茄果肉中番茄红素含量性状的遗传分析

为更快更好地进行番茄果肉颜色的评定,定位相关QTLs以改良果肉的颜色品质,本研究选用果肉番茄红素含量显著不同的2个番茄品系,利用分光光度计法测定番茄红素含量,并通过P1、P2、F1、F2、B1和B2六世代联合分析法,研究分析了果肉番茄红素含量的遗传规律。结果表明：F2、B1、B2分离世代群体呈双峰或单峰偏态分布,主基因的加性效应明显,多基因对番茄红素含量分布有较大影响,存在明显的主基因多基因特征,显示番茄果肉番茄红素含量的遗传为多基因控制的数量性状;果肉番茄红素含量的遗传符合一个加性主基因和加性-显性多基因模型(D-2模型)。主基因遗传率较高,为27.39%~66.93%;多基因遗传率较低,为12.09%~48.44%。所以,利用有性杂交育种提高和固定高番茄红素性状,在早期世代进行选择有利于发现新QTLs位点。     

醋栗番茄耐低磷胁迫的遗传规律分析

为了研究野生醋栗番茄耐低磷胁迫的遗传规律,以耐低磷胁迫野生醋栗番茄和低磷胁迫敏感栽培番茄003为材料,通过杂交自交构建6世代(P1,P2,F1,B1,B2和F2)群体,采用植物数量性状主基因+多基因混合遗传模型方法,分析番茄缺磷症状叶遗传规律。结果表明:野生醋栗番茄LA722耐低磷胁迫遗传符合MX2-ADI-AD模型,即2对加性-显性-上位性主基因+加性-显性多基因控制。2对主基因加性效应相等且为负,显性效应均为正,且第2对主基因的显性效应大于第1对主基因,2对主基因的遗传以负向的加性效应为主,多基因的遗传以显性效应为主。B1、B2和F2群体中主基因的遗传率分别为31.44%、81.47%和78.35%,多基因遗传率均为0,环境因素为18.53%~68.56%。利用本研究结果不仅为耐低磷胁迫的育种设计奠定理论基础,同时也为耐低磷胁迫资源的挖掘和筛选提供理论依据。     

棉花不同茸毛性状近等基因系的选育与生理生化特性研究

为了培育具有抗病虫优良性状的棉花新品种,并对棉花多茸毛基因进行定位克隆,从棉花三元杂种后代中选育了绿叶无茸毛和绿叶多茸毛近等基因系。以该近等基因系为供试材料,测定了具有不同茸毛性状的棉株间光合速率、叶绿素含量、苯丙氨酸解氨酶(PAL)活性以及单宁含量的变化,通过光合生理与相关生化指标测定相结合,初步探讨棉花不同茸毛性状近等基因系材料间生理生化特性的差异,为今后选育具有优良性状的棉花新品种提供依据。结果表明,无茸毛与多茸毛棉花近等基因系的叶绿素a、b及总量的动态变化趋势基本一致,蕾期较高,花期、铃期降低;净光合速率变化趋势一致,二者均呈先上升后下降再上升的趋势,在铃期达到了顶峰。因此,光合速率与叶绿素含量变化趋势在近等基因系材料间差异不明显。无茸毛和多茸毛棉花纤维和种皮单宁含量变化具有相同的趋势,均为先升高再降低,纤维中的PAL活性多茸毛棉株逐渐下降,无茸毛棉株下降后再升高,而种皮中PAL活性上升至最高值后保值不变。PAL活性与单宁含量在材料间差异较大,绿叶多茸毛棉株高于绿叶无茸毛棉株。表明PAL活性和单宁含量与茸毛性状存在一定的相关关系。     

基于SNP和SSR分子标记的番茄种质资源遗传多样性分析

为分析不同番茄种质的遗传多样性,利用120个SNP和29个SSR标记对210份番茄自交系进行基因分型。结果表明,SSR具有较高的多态性,而SNP检测到更高的基因多样性。在预先划分的3个亚群中,樱桃番茄遗传变异最高,常规番茄品种次之,现代番茄品系最低,说明早期育成的番茄品种仍具有较为丰富的遗传多样性。群体结构分析发现,SNP可将3个亚群区分开,同时常规番茄进一步分为粉果番茄和红果番茄2个小亚群。SSR的分析结果与SNP和预先的分类并不一致,未能将常规番茄和现代品系完全区分开。遗传距离分析显示,SNP具有更高的分辨率,可以区分所有供试材料,有6对材料组合未被SSR数据区分开。总的来说,在栽培番茄遗传多样性分析中,SNP标记具有更高的效率。     

棉花表型性状基因的SSR标记定位

本文以两个陆地棉多标记基因系T582和T586,以及杂交获得的F_1、F_2及F_3代作为试验材料,利用11对SSR引物对F_2群体的120个单株的DNA样品进行多态性分析,并利用F_2和F_3群体对F_2群体对应单株的13个表型性状进行基因型的判定,结果得到了3个与表型性状基因连锁的SSR标记,分别是红茎基因(R_1)与J178连锁、遗传距离为24.9cM,簇生铃基因(CL_1)与J236连锁,遗传距离为46.0cM,茸毛基因(T_1)与J252连锁,遗传距离为28.5cM,其中R_1、CL_1、J178和J236在同一连锁群上。红茎和植株茸毛是具有抗虫性能的形态性状,用SSR标记这些性状将有助于提高育种家的育种效率。     

水稻主要数量性状遗传研究的进展与育种

什么叫数量性状呢?一般认为受多基因控制、性状表现连续变异对环境变化反应敏感的性状叫数量性状，对动、植物而言，也叫经济性状。那么，水稻数量性状是怎样遗传的呢？从数量性状正、反交的基本一致性，以及在一些数量性状遗传试验里，亲本、F1、F2和F3的表现型频率分布与根据多基因独立分配所期望的频率分布的一致性等现象看出，控制数量性状的多基因也位于染色体上。果蝇腹刚毛数研究证明，多基因和主基因连锁在一起，并位于核内染色体上。所以数量性状的遗传也应遵循三个基本遗传规律。本综述旨在对水稻主要数量性状的遗传的大量实验…     

早熟甘蓝型油菜开花期的遗传分离分析

随着中国农村产业结构和种植模式调整,早熟油菜在油菜产业链中的重要地位日益凸显;但油菜早熟性与丰产性和抗逆性存在较大矛盾,使得早熟品种的选育受到极大制约,挖掘早熟种质资源对早熟品种的选育具有重要意义。本研究前期获得一个丰产性好的早熟甘蓝型油菜品系GRG177,以GRG177 (P_1)与甘蓝型油菜品系GRD328 (P_2)为亲本,构建六世代遗传群体(P_1, P_2, F_1, B_1, B_2和F_2),利用主基因+多基因混合遗传模型完成了花期性状的多世代联合分析。结果表明,初花期受2对加性-显性-上位性主基因+加性-显性多基因控制,花期受2对加性-显性-上位性主基因+加性-显性-上位性多基因控制,终花期受1对加性-显性主基因+加性-显性-上位性多基因控制。花期性状在分离世代中具有较高的遗传率(51.79%～96.80%)。本研究为早熟油菜品种选育、GRG177花期性状基因定位与克隆提供较好基础。     

由番茄果实表面色差估计的番茄红素含量遗传分析

本试验选择两个果实表面色差a/b显著不同的番茄品系,通过P1、P2、F1, F2、B1和B2六世代的分析方法,研究了由番茄果实表面色差a/b估计番茄红素含量的遗传规律。结果表明：由番茄果实表面色差估计番茄红素含量的遗传符合两对加性-显性-上位主基因遗传模型(B_1_1),主基因效应在B1、B2和F2 三个世代的遗传率分别为50.31％、65.15％和32.77％。     

基于主基因+多基因混合模型的甜高粱茎秆含糖量基因遗传分析

此文以茎秆含糖量（锤度）较低的粒用高粱品系LR625（P1）和茎秆含糖量（锤度）较高的甜高粱品系Rio（P2）及其杂交后代F1、F2群体为研究对象,运用主基因+多基因混合遗传模型对茎秆含糖量的遗传进行了联合分离分析。结果表明：茎秆含糖量性状受2对加性-显性-上位性主基因和加性-显性多基因共同控制。2对主基因的加性效应分别为-4.004和-2.116,显性效应分别为0.084和-0.462,主基因遗传力为83.27%,多基因遗传力为7.38%。这说明锤度性状主要受2对主基因的作用,而且2对主基因均以加性效应为主。这一研究结果为茎杆含糖量性状的基因定位和育种选择提供了理论依据。     

玉米穗轴粗性状的主基因+多基因遗传分析

穗轴粗性状是影响果穗籽粒脱水速率的一个重要因素，当前对穗轴粗性状的数量遗传规律研究较少。以经典玉米自交系PHB1M/丹340（组合Ⅰ），PH4CV/丹598（组合Ⅱ）构成的P1、F1、P2、B1、B2和F2 6世代群体为材料，运用主基因与多基因混合遗传模型分析方法，研究玉米穗轴粗性状遗传规律。结果表明：玉米穗轴粗性状在2组合的F1代呈现中亲遗传。组合Ⅰ中穗轴粗性状最佳模型符合C-0，表现为加性-显性-上位性多基因遗传；组合Ⅱ穗轴粗遗传符合D-2，表现为一对加性主基因+加性-显性多基因遗传，其中多基因起主要作用。穂轴粗性状在B2世代多基因遗传率最大，育种中可以在遗传率较高的世代通过轮回选择或聚合回交等方法累积增效基因，进而选育出穂轴粗细适宜的材料，培育出高产、优质、适宜机收的优良玉米品种。     

Biological Activity and Quantification of Suspected Allelochemicals from Alfalfa Plant Parts

Autotoxicity restricts reseeding of alfalfa (Medicago sativa L.) after alfalfa until autotoxic chemical(s) breaks down or is dispersed into external environments. A series of aqueous extracts from leaves, stems, roots and seeds of alfalfa ‘Vernal’ were bioassayed against alfalfa seedlings of the same cultivar to determine their autotoxicity. The highest inhibition was found in the extracts from the leaves. Extracts at 40 g dry tissue l^?1 from alfalfa leaves were 15.4, 17.5 and 28.7 times more toxic to alfalfa root growth than were those from roots, stems and seeds, respectively. A high‐performance liquid chromatography (HPLC) analysis with nine standard compounds showed that the concentrations and compositions of allelopathic compounds depended on the plant parts. In leaf extracts that showed the most inhibitory effect on root growth, the highest amounts of allelochemicals were detected. Among nine phenolic compounds assayed for their phytotoxicity on root growth of alfalfa, coumarin, trans‐cinnamic acid and o‐coumaric acid at 10^?3 m were most inhibitory. The type and amount of causative allelochemicals found in alfalfa plant parts were highly correlated with the results of the bioassay, indicating that the autotoxic effects of alfalfa plant parts significantly differed.     

Changes in Seed Yield and Quality with Maturity in Onion (Allium cepa L., cv. 'Early Cream Gold')

Development of onion (Allium cepa L., cv. ‘Early Cream Gold’) seed under cool climate conditions in Tasmania, Australia occurred over a longer duration than previously reported, but similar patterns of change in yield components were recorded. In contrast to previous studies, umbel moisture content declined from 85 to 67 % over 57 days while seed moisture content decreased from 85 to 31 %. Seed yield continued to increase over the duration of crop development, with increasing seed weight compensating for seed loss resulting from capsule dehiscence in the later stages of maturation. Germination percentage was high and did not vary significantly from 53 to 77 days after full bloom (DAF), but mean germination time declined and uniformity of germination increased significantly over the same time period. The percentage abnormal seedlings declined with later harvest date, resulting in highest seed quality at 77 DAF. The results of this study suggest that the decision to harvest cool climate onion seed crops before capsule dehiscence will result in a loss of potential seed yield and quality.     

Location of a high-lysine gene and the DDT-resistance gene on barley chromosome 7

Summary The high-lysine gene in Risø mutant 1508 conditions an increased lysine content in the endosperm via a changed protein composition, a decreased seed size, and several other characters of the seed. The designation lys3a, lys3b, and lys3c, is proposed for the allelic high-lysine genes in three Risø mutants, nos 1508, 18, and 19. Linkage studies with translocations locate the lys3 locus in the centromere region of chromosome 7. A linkage study involving the loci lys3 and ddt (resistance to DDT) together with the marker loci fs (fragile stem), s (short rachilla hairs), and r (smooth awn) show that the order of the five loci on chromosome 7 from the long to the short chromosome arm is r, s, fs, lys3, ddt. The distance from locus r to locus ddt is about 100 centimorgans.     

A note on the origin of Kalanchoë x vadensis Boom & Zeilinga (Crassulaceae)

Summary K x vadensis is a hybrid of K. blossfeldiana and K. marmorata obtained after doubling the number of chromosomes.     

Simultaneous Determination of Four Phenolic Acids in Radix Salviae Miltiorrhizae Formula Granules by QAMS

[Objectives]This study aimed to establish a QAMS(quantitative analysis of multi-components by single-marker)method for simultaneous determination of four phenol...     

Avoidance of leaf rust fungi in wild relatives of cultivated cereals

Summary Avoidance of rust fungi that was based on poor appressorium induction was previously found in Hordeum chilense. In the present study 95 accessions of Triticeae were screened for avoidance of Puccinia hordei. The percentage of appressorium formation per germinated spore ranged from 6 to 90%. On none of the 41 accessions of Aegilops, Agropyron, Elymus, Secale, Thinopyrum or Triticum studied was the rate of appressorium formation lower than 25%. Lower rates of appressorium formation were, however, found on accessions of wild barley species Hordeum brachyantherum, H. marinum, H. parodii and H. secalinum. Its implications in cereal breeding are discussed.     

Variation in forage grasses as hosts of the root-knot nematode Meloidogyne naasi (Franklin) and selection for resistance in ryegrass

Summary Reactions of 13 grasses to Meloidogyne naasi varied with species; ryegrasses, fescues and their hybrids were generally susceptible and cocksfoot and timothy resistant. Marked variation in host resistance levels occurred between genotypes within cultivars.Selection of single plants, followed by tests on replicate tillers, identified resistant and susceptible genotypes in both Italian and perennial ryegrass cultivars. Resistant plants had few nematode-induced galls and fewer females and eggs than susceptibles. There was more or less continuous variation, with many genotypes intermediate between extremes of resistance and susceptibility. Selected resistant and susceptible genotypes are of use in assessing variation in nematode populations and as controls for breeding and selection programmes.     

Current and future strategies in breeding lentil for resistance to biotic and abiotic stresses

Lentil production is limited by lack of moisture and unfavorable temperatures throughout its distribution. Waterlogging and salinity are only locally important. Progress has been made in breeding for tolerance to drought through selection for an appropriate phenology and increased water use efficiency and in breeding for winter hardiness through selection for cold tolerance.The diseases rust, vascular wilt, and Ascochyta blight, caused by Uromyces viciae-fabae, Fusarium oxysporum f. sp. lentis, and Ascochyta fabae f. sp. lentis, respectively, are the key fungal pathogens of lentil. Cultivars with resistance to rust and Ascochyta blight have been released in several countries and resistant sources to vascular wilt are being exploited. Sources of resistance to several other fungal and viral diseases of regional importance are known. In contrast, although the pea leaf weevil (Sitona spp.) and the parasitic weed broomrape (Orobanche spp.), and to a lesser extent the cyst nematode (Heterodera ciceri), are significant yield reducers of lentil, no sources of resistance to these biotic stresses have been found. Directions for future research in lentil on both biotic and abiotic stresses are discussed.     

Mechanisms and diversity of resistance to sorghum shoot fly,Atherigona soccata

Sorghum shoot fly, Atherigona soccata, is one of the important pests of postrainy season sorghums. Of the 90 sorghum genotypes evaluated for resistance to this pest, RHRB 12, ICSV 713, 25026, 93046 and 25027, IS 33844‐5, Giddi Maldandi and RVRT 3 exhibited resistance in postrainy season, while ICSB 463, Phule Anuradha, RHRB 19, Parbhani Moti, ICSV 705, PS 35805, IS 5480, 5622, 17726, 18368 and 34722, RVRT 1, ICSR 93031 and Dagidi Solapur showed resistance in rainy season, suggesting season‐specific expression of resistance to A. soccata. ICSB 461, ICSB 463, Phule Yasodha, M 35‐1, ICSV 700, 711, 25010, 25019 and 93089, IS 18662, Phule Vasudha, IS 18551 and 33844‐5 and Barsizoot had fewer deadhearts than plants with eggs across seasons, suggesting antibiosis as one of the resistance mechanism. Five genotypes exhibited resistance with high grain yield across seasons. Correlation, path and stepwise regression analyses indicated that leaf glossiness, seedling vigour, trichome density, oviposition and leaf sheath pigmentation were associated with the expression of resistance/susceptibility to shoot fly, and these can be used as marker traits to select and develop shoot fly‐resistant sorghums.     

Breeding forage grasses for organic conditions

Herbage yield trials are necessary to test if candidate varieties are well suited for organic conditions. In order to elucidate a particular suitability for organic conditions, we run such trials in parallel under both organic and conventional conditions. Here, we report on second and third year results of the sowings 2004 and 2005. These trials are part of a targeted breeding programme for organic conditions. Irregular colonisation of pure grass plots with adventitious plants, in particular white clover, was recognized as a major constraint to the quality of the results obtained under organic conditions. The coefficients of variance in dry matter yield almost doubled when compared to conventional trials, and significant differences in annual yield among varieties were rare. However, when herbage yield was corrected for the estimated fraction of adventitious plant colonization at each cut, the number of instances with statistically significant differences for annual yield among varieties increased more than fourfold. Dry matter yields under organic and conventional conditions were significantly and positively correlated. However, analysis of variance showed a significant culture type by variety interaction for annual dry matter yield in 12 out of 24 trials. When diploid and tetraploid varieties of the same Lolium species were tested in one common trial, only tetraploid varieties were identified as being particularly well suited for organic conditions, while in these trials, the great majority of apparently poorly suited varieties were diploid. This suggests that breeding tetraploid Lolium varieties is promising when aiming at a favourable response to organic agriculture.