黄瓜数量性状遗传距离与杂种优势关系的研究

探讨数量性状遗传距离与杂种优势的关系,为黄瓜新品种的选育提供理论依据。选择5份黄瓜自交系材料作为母本,6份黄瓜自交系材料作为父本,按半双列杂交法配制出29个杂交组合,对11份黄瓜自交系材料的7个数量性状进行杂种优势分析和聚类分析,并研究数量性状遗传距离与杂种优势的关系。研究结果表明,各数量性状均有不同程度的正向杂种优势,其中株高、结瓜数和单株产量的杂种优势最为明显,而单果重、主蔓20节内雌花数、果实长和果实粗的杂种优势比较微弱。11份黄瓜自交系被分为3大类群,地理远近与遗传距离之间并不存在必然的联系。结瓜数的中亲优势指数和杂种优势指数、果实长和果实粗的中亲优势指数及单株产量的超亲优势指数与亲本遗传距离之间存在显著的相关关系,而株高、单株产量的中亲优势指数和杂种优势指数与亲本遗传距离之间存在极显著的相关关系,大部分数量性状的杂种优势都随着遗传距离的增大而增大。在进行黄瓜种质资源评价时,不能以地理关系作为唯一标准;在进行黄瓜杂交育种时,可根据育种目标,适当选择较大的遗传距离来获得杂种优势。     

肉苁蓉种子产量构成因子分析

为明确构成肉苁蓉种子产量的关键因子及其对种子产量的影响,采用相关、通径和多元回归分析等方法对肉苁蓉花部主要形态性状与单株种子产量的关系进行分析,得出与种子产量显著相关的7个构成因子为有效果数(X1)、总果数(X2)、单果种子数(X3)、花序长(X4)、大苞片长(X5)、结实率(X6)和花数(X7);其中有效果数(X1)对种子产量(Y)的直接效应最大,最优回归方程为:Y=-8.721+0.0919X2+0.00954X3。结果表明,肉苁蓉单株种子产量可以通过果数和单果种子数进行预测,打顶、增加授粉量以及选育种子高产品种等措施有助于种子产量的提高。研究结果为制定肉苁蓉的育种目标和栽培措施提供了科学依据。     

应用遣传距离预测爆裂玉米杂种优势

根据80个爆裂玉米自交系数量性状的表现估算了它们之间的遗传距离及它们之间随机组配的67个杂交组合F_1代小区产量、爆粒率和膨胀倍数的杂种优势。相关和回归分析表明,F_1代产量的成分照优势与其双亲之间的遗传距离呈显著的二次曲线关系,而F_1代品质特性爆粒率和膨胀倍数的对照优势与其双亲之间的遗传距离无确定性关系。因此,可以根据亲本间数量性状的综合遗传差异——遗传距离预测爆裂玉米杂种一代产量优势。     

大豆亲本间遗传距离与杂种优势的相关性研究

为提高杂交育种效率,有必要对杂种优势预测进行探索。本研究选用国内外不同地区10份材料,按NCⅡ不完全双列杂交法组配45个杂交组合,利用SSR分子标记遗传距离预测大豆亲本间杂种优势。结果表明：10份亲本中检测到417个多态性等位基因变异,多态性位点变化范围为2~5个,遗传相似系数(GS)变幅为0.520~0.695,平均GS值为0.5996。10份供试材料被分为两大类,F₁杂种优势值从3.4%~42.1%,F₁性状均具有不同程度正向杂种优势。其中,单株粒数杂种优势与遗传距离的相关系数为0.461,达显著水平。其余8个农艺、品质性状与遗传距离的相关系数未达显著水平。初步认为,利用该174个SSR分子标记检测亲本间遗传差异,对本研究10份大豆亲本间杂种优势预测效果不显著。利用分子标记遗传距离预测大豆亲本杂种优势的方法有待进一步研究。     

杂交水稻产量及农艺性状杂种优势分析

为探讨杂种优势与双亲值、双亲一般配合力（GCA）、组合特殊配合力（SCA）、双亲遗传距离的关系,利用10个不育系和10个恢复系,按不完全双列杂交配制100个组合,对杂交水稻产量及农艺性状的杂种优势进行了分析,探索杂种优势的预测方法。结果表明：杂种一代的超亲优势和对照优势主要体现在穗长、每穗总粒数、每穗实粒数几个性状上,其具有正向超亲优势组合的比例分别达到61.0%、66.0%和53.0%,具有正向对照优势的比例分别为62.0%、78.0%和79.0%,结实率性状具有正向对照优势的比例也达到58.0%。杂种优势与父母本值、父母本平均值、高亲值、低亲值及父母本差值都有较为密切的关系,超亲优势与高亲值在8个性状上都极显著相关;对照优势与母本值、父母本平均值、高亲值都呈显著或极显著正相关。杂种优势与SCA和亲本的GCA效应值密切相关,特别是对照优势与SCA和双亲的GCA都呈显著或极显著正相关,同时与父母本的GCA之差和之和都有较大的关系。杂种优势与遗传距离的关系比较复杂,当遗传距离在5~5.5范围内,双亲的距离越远,杂种优势越强。     

陆地棉配合力与杂种优势、遗传距离的相关性分析

 用10个陆地棉亲本进行不完全双列杂交,共配置了45个组合,计算亲本的一般配合力（GCA）、特殊配合力(SCA)、杂种优势,并结合SSR标记研究了陆地棉亲本配合力与杂种优势、遗传距离之间的相关关系。配合力分析发现,10个亲本的一般配合力和特殊配合力存在显著或极显著差异。分析亲本配合力、杂种优势和遗传距离的相关性发现,子棉产量、皮棉产量、衣分的一般配合力和杂种优势呈显著或极显著相关,纤维长度、比强度、麦克隆值、株高、果枝数、单株铃数、铃重、子棉产量、皮棉产量、衣分的特殊配合力和杂种优势均呈极显著正相关,而与遗传距离相关均不显著。单株铃数、铃重、子棉产量、皮棉产量、衣分的杂种优势与遗传距离均为正向显著或极显著相关。在育种实践中这些显著或极显著相关的性状可能具有较高的改良潜力。     

西瓜数量性状遗传距离及杂种优势分析

为研究西瓜数量性状的遗传距离和杂种优势，对8份西瓜亲本采用NC-Ⅱ设计配制16个杂交组合，对杂交组合的7个数量性状进行相关性分析、主成分分析和杂种优势研究。结果表明，坐果节位和单果重显著正相关，中心可溶固形物含量和边部可溶固形物含量极显著正相关。主蔓长度、坐果节位、单果重、果皮厚度、中心可溶固形物含量、边部可溶固形物含量和果形指数7个数量性状可以综合成为3个主成分，且3个主成分构成的信息量可以解释总信息量的87.3132%。8个亲本间遗传距离介于0.3315~1.5121之间，A02×B04组合的单果重中亲优势和超亲优势最为突出，分别达到42.47%和37.38%。     

二倍体苜蓿主要性状配合力及杂种优势分析

以3份花药离体培养单倍体苜蓿与2份扁蓿豆材料作为亲本,组配10个杂交组合,分析7个主要农艺性状的配合力,探究苜蓿与扁蓿豆的杂种优势与亲本一般配合力(GCA)、特殊配合力(SCA)和遗传距离之间的相关关系。结果表明,节间长受加性效应和非加性效应共同影响,株高、节间数、单株产量其遗传主要受加性效应影响较大。各性状的杂种优势在不同组合间差异较大。在二倍体苜蓿与扁蓿豆种间杂交组合中,XJ-3×CY-5和CY-35×HB各农艺性状特殊配合力的效应值适宜,杂种优势强,可作为优良杂交组合进行利用。研究表明,可通过组合间的SCA与杂种优势来提高亲本的选配效率,但利用SRAP标记遗传距离预测苜蓿杂种优势还有待进一步研究。     

浙优21茎秆抗倒伏性状的相关性及通径分析

籼粳杂交稻浙优21杂种优势强,产量高,剖析其抗倒伏性状的构成因素,探明相应的栽培技术对其大面积高产生产具有重要意义。对浙优21的12个抗倒伏构成性状进行相关、多元逐步回归和通径分析。株高（X1）、节间长（X5）、全秆鲜重（X6）、鲜穗重（X7）、全秆干重（X8）、干穗重（X9）、抗折力（X10）、茎直径（X11）和茎壁厚（X12）与倒伏系数相关均达极显著水平,相关系数分别达0.84、-0.61、0.91、0.89、0.88、0.85、-0.76、-0.71和-0.68,这些性状构建了浙优21茎粗秆硬,耐倒性强的品种特性。倒伏指数（Y）与上述性状的最优回归方程为Y=-44.6914+1.5210X1-1.3896X5+3.0261X6+1.4055X7+2.7725X8-2.1025X9-2.0159X10+2.0274X11+2.9196X12。通径分析表明浙优21抗倒能力主要取决于株高、节间长、茎直径和茎壁厚等性状。栽培上应控制后期的氮肥施用,降低植株高度,同时增加硅钾肥施用,提高茎秆韧性,增强抗倒能力。     

近江牡蛎养殖群体数量性状间的相关及通径分析

为了查明近江牡蛎养殖群体数量性状间的相关性及影响产量的因素组成,随机选取140只2.5龄贝,对其形态性状（壳长、壳高、壳宽）和重量性状（活体重、软体重）等5个数量性状进行测量,并应用遗传相关、多元回归、通径分析、决定系数等方法讨论了形态性状对重量性状的影响。结果表明受测的5个数量性状间的相关性均达到显著水平（P < 0.05）,相关系数从0.16710到0.81988。形态性状对活体重和软体重具有相同的影响：对二者起直接作用最大的均是壳高,其值分别为33.84%和34.20%;对二者起间接作用最大的均为壳长,其值分别为17.84%和13.23%;壳宽的作用最小。多元回归分析建立了壳长（x1）、壳高（x2）、壳宽（x3）3个估计活体重（Y1）和软体重（Y2）的回归方程,分别为: Y1 = -104.50715 + 1.29795x1 + 0.91435x2 + 1.39589x3 (R2 = 0.7818), Y2 = -10.54062 + 0.14956x1 + 0.14361x2 + 0.12205x3 (R2 = 0.6008)。本研究结果为近江牡蛎选择育种提供了理论依据,即以提高活体重或软体重为目标,主要选择壳高,同时加强对壳长的协同选择。     

Relationship between heterosis and genetic distance based on morphological traits and AFLP markers in pepper

Genetic diversity is considered as one of the criteria for the selection of parents for hybrid breeding. The present study was undertaken to evaluate genetic divergence among seven pepper cultivars and to assess the relationship between heterosis and parental genetic distance. Twenty‐one F₁ hybrids and seven parents were evaluated for 15 morphological characters in a greenhouse and in the field. The parents were examined for DNA polymorphisms using six amplified fragment length polymorphism (AFLP) primer combinations. Cluster analysis using two genetic distance measures grouped the seven parents differently. Mid‐parent and high‐parent heterosis was observed for most characters. Most hybrids outperformed the parental lines for fruit yield, earliness and plant height. Morphological and AFLP‐based distance measurements were efficient enough to allocate pepper genotypes into heterotic groups. The correlations of morphological distances with mid‐parent heterosis were significant for days to flowering and maturity, suggesting earliness can be predicted from morphological distances of parental lines. However, the correlations of AFLP‐measured genetic distances with mid‐ and high‐parent heterosis were non‐significant for all characters, except for fruit diameter, and proved to be of no predictive value.     

Inheritance mode of fruit traits in melon: Heterosis for fruit shape and its correlation with genetic distance

Fruit quality traits were studied in 12 exotic accessions and their hybrids with a “Piel de Sapo” inodorus melon cultivar. The genetic relationships among these genotypes were assessed with 16 microsatellite markers, which agreed with the classification of Cucumis callosus, C. pubescens and C. trigonus as accessions within C. melo. There were very large differences between all the exotic accessions and “Piel de Sapo” genotype for fruit traits. When the hybrids were analysed, three different situations regarding mid parent heterosis were found, depending on the trait: no heterosis (soluble solid concentration), highly variable, from negative to positive (fruit weight and fruit diameter) and general positive heterosis (ovary shape, fruit length and fruit shape). Best parent heterosis for fruit shape was also common among hybrids. A highly significant correlation (r = 0.81) was detected between fruit shape and fruit length heterosis, suggesting that fruit shape heterosis is caused mainly by the enlargement of the fruit longitudinally. A highly significant correlation (r = 0.84) between heterosis for fruit shape and genetic distance, as estimated with microsatellites, was also found. These results, together with the previously reported observation that melon fruit shape is polygenic and highly heritable, makes the genetics of melon fruit shape a suitable system for dissecting the genetic and molecular basis of heterosis.     

黄瓜早熟及丰产性与主要农艺性状的相关性分析

通过对黄瓜杂种一代苗期及成株33个性状的性状值、超中优势、超亲优势进行了全面系统地研究,分析了黄瓜丰产及早熟两个性状的主要构成因素及与其他性状间的相关性。结果表明,总瓜条数、单瓜重、主枝瓜重量、主枝单瓜重、主枝瓜条数、侧枝瓜条数、侧枝单瓜重、侧枝瓜重量、茎粗和生育天数等性状是决定总产量最为重要的因素并具有较强的杂种优势,无论在性状值、超亲还是超中优势中均达到极显著相关。前期产量主要决定于第一雌花节位和雌花节率及主侧枝瓜条数和瓜重、株高、叶面积等性状,达到显著水平,其中第一雌花节位和雌花节率在性状值、超亲和超中优势中都呈极显著相关性,说明这两个性状是决定黄瓜早熟性的决定性的因素并具有较强的杂种优势。根据试验结果分析了在黄瓜育种和生产过程中为达到早熟高产目的应当注意的几个主要问题。     

Indica-Japonica differentiation of paddy rice and its relationship with heterosis

The Indica‐Japonica differentiation of three photoperiod‐sensitive and/or thermosensitive genetic male‐sterile rice (PGMS or TGMS, respectively) lines and 47 male parental lines from seven ecotypes were studied for their restriction fragment length polymorphism marker data to determine which ecotype crosses with the three PGMS and/or TGMS lines could lead to higher yield potential, and to estimate the relationship between the Indica‐Japonica differentiation of parents and heterosis in grain yield and its components. The results indicated that hybrids derived from ‘N422s’ and the early‐middle ripening Indica varieties from southern China, and hybrids between ‘Pei'ai64s’ and three Japonica ecotypes, including North‐eastern Japonica varieties, restoring lines of Japonica hybrid rice and north China Japonica varieties, showed the highest grain yields. There was less variation of yield among the F1s between ‘108s’ and the seven ecotypes than among the other F₁s. Highly significant positive correlations between heterosis of the F₁ yield and genetic distance of the parents were detected, although the correlation between F₁ yield performance and genetic distance did not reach a significant level. Considerable variation of correlation between heterosis and genetic distance was also detected in the Indica × Indica crosses and Indica × Japonica crosses. There was much higher correlation (r = 0.63) between the F₁ yield performance and the genetic distance of parents in the Indica × Indica crosses than in the others. It is proposed that a genetic distance of 0.4‐0.8 between the two parents of hybrid rice might be appropriate not only for F₁ performance, but also for heterosis.     

玉米遗传距离测量方法及其与产量的杂种优势和特殊配合力的关系

本文以21个玉米自交系和按15×6不完全双列杂交设计配制的90个单交种为材料,对遗传距离测量方法进行了初步探索,对遗传距离与产量的杂种优势及特殊配合力的关系进行了研究。方法的探索包括主成分法(刘来福,1979)与枢轴凝聚法(C.R.R(?)o,1952)2种遗传距离计算方法的比较,以及对作者提出的分类指标(性状)选择的新方法的分析。结     

粳稻数量性状遗传距离与杂种优势的关系

研究粳稻资源分类方法,测定数量性状遗传距离,探讨数量性状遗传距离与杂种优势的关系。对30份粳稻资源材料的12个数量性状进行了主成分分析和聚类分析,并使用作图法研究了数量性状遗传距离与杂种优势指数之间的关系。30份粳稻资源的12个数量性状可归纳为5个主成分因子,其累积贡献率为86.84%。在评价粳稻种质资源时,首先应考虑每穗总粒数和每穗实粒数等穗粒因子,其次为群体具备一定的高峰苗数,最后应该协调植株的生育期、秧苗素质及株型等因子。30份粳稻资源被归为5组,地理远近和亲缘关系与遗传距离并不存在必然的联系。遗传距离与杂种优势的关系较为复杂,并非遗传距离越大杂种优势越明显。在进行粳稻资源评价时,不能以地理或亲缘关系作为唯一标准;在亲本选配时,应选择遗传距离中等偏大的材料。