基于ILs玉米抗旱相关位点分析

选用抗旱性优良的玉米自交系郑独青为供体,采用高代回交方法构建以自交系昌7-2为主要遗传背景的导入系群体,通过SSR标记检测群体中供体等位基因的导入频率,利用卡方检验对等位基因导入频率的偏离进行检测,同时结合表型-基因型方差分析的方法,对抗旱群体进行抗旱性相关位点分析。结果表明,卡方检验发现显著位点33个,方差分析检测到24个,其中15个位点被两种方法同时检测到。     

野生大豆染色体片段代换系百粒重的选择牵连效应及响应分析

利用野生大豆导入系群体和多位点扫描分析方法研究了针对百粒重性状的选择牵连效应,找到与百粒重性状相关联的位点,并分析了这些位点在选择条件的响应。随机群体28.10%的位点出现偏分离(P0.05),经百粒重选择后等位基因偏分离比例减少,偏分离程度加大。标记异常偏分离率缩小到4.13%和23.14%,卡方值变幅缩小至0~166.67和0.01~81.30。对随机群体和选择群体的供体片段导入频率,在P0.05水平下进行卡方分析,定位到与百粒重相关的的12个位点。     

玉米人工合成群体S2遗传变异SSR标记评估

本研究利用SSR标记技术分析2个玉米人工合成群体S2分子水平的遗传变异，为群体合成及自交后代的选择提供一定理论依据。结果表明，40对引物在2个群体S₂中共扩增出420个等位位点，每个SSR座位的等位基因数目为3～25个，平均为10.5个。GP-5 S2的多态位点数、多态位点比例、基因型数、变异系数、基因杂合度等均大于GP-4 S₂，表明GP-5 S₂入选株系的遗传变异较GP-4 S₂大。遗传距离比较表明，不同群体S₂间平均遗传距离大于群体内株系间平均遗传距离，群体内株系间平均遗传距离又远远大于株系内个体间平均遗传距离。根据遗传距离，可将60个单株分为5个大类10个亚类，GP-4 S₂部分株系和GP-5 S₂部分株系聚在同一亚类，表明GP-4 S₂和GP-5 S₂的部分株系可能有相似的遗传背景。因此，玉米人工合成群体亲本材料的选择应将田间鉴定与SSR检测结合，并根据育种目标确定合成材料的多少，而在自交后代选择中则应侧重系间选择。     

适合中国南方生态区玉米优良群体的创建与改良

在基础群体BC₄中输入热带血缘,创建了适合中国南方生态区的玉米优良群体BCC₀,采用S₁法对BCC₀进行一轮改良得到改良群体BCC₁.在产量等11个农艺性状上,BCC₁比BCC₀,BCC₁、BCC₀比BC₄均有明显改善.BCC₁在产量等主要农艺性状一般配合力效应上具有     

利用野生大豆回交导入系定位油分含量QTL

以野生型大豆ZYD00006(供体亲本)与黑龙江省主栽品种绥农14(轮回亲本)所构建的回交导入系(832株)为研究材料,利用单因素方差分析方法在11条连锁群上定位到23个QTL位点(P≤0.01),其中4个正效应,19个负效应。导入系群体经过严格的油分含量筛选鉴定,得到13个油分含量性状明显大于轮回亲本的导入系株行和20个油分含量明显小于轮回亲本的导入系植株。利用这33个特殊株行(选择群体)结合随机对照群体,通过基于遗传搭车原理的卡方分析,检测到分布于15个连锁群上的25个与大豆油分含量相关的标记位点,其中11个正效应,14个负效应。两种方法共检测到34个位点,新发现11个位点,两种方法均检测到的有14个位点。     

大豆定向选择群体耐旱性位点基因型分析及QTL定位

利用Clark导入到红丰11为背景的回交导入系进行萌芽期和苗期的连续性耐旱鉴定,经萌芽期鉴定,获得36个耐旱定向选择导入系。对耐旱选择导入系进行全基因组SSR标记扫描,并以随机群体作为对照,计算供体基因型的导入频率,利用卡方测验检测显著偏分离的SSR标记位点,并结合GGT图示基因型软件对各染色体连锁群进行分析。其中在L连锁群的Satt398和Satt156两个位点有显著的供体片段“超导入”现象,供体基因型导入频率为0.9167和0.9583,卡方值高达182和201.5。另外,在F连锁群的Satt423,K连锁群的Satt167以及N连锁群的Sat_084等位点也出现供体导入片段的偏分离现象。同时,对萌芽期耐旱鉴定中相对发芽率表现超亲的35个株系采用性状－标记间的单向方差分析(P<0.01)和QTL定位, 共检测到14个控制相对发芽率的QTL,分布在4个连锁群上,其中与卡方测验检测的结果相比较,在Satt156,Satt423,Sattt167等位点具有一致性,说明这些位点是与大豆耐旱性紧密相关的QTL位点。以上结果为进一步开展大豆耐旱性有利基因的精细定位、克隆和分子设计育种奠定了基础。     

玉米回交后代群体中供体基因组成分分析

以郑58为受体亲本,昌7-2为供体亲本,通过杂交、回交和79对亲本间有多态的SSR标记,分析BC₂F₁和BC₃F₁世代供体的基因组成分。结果表明：BC₂F₁世代单株内的供体染色体片段数平均为11.4个,BC₃F₁世代为4.8个,从BC₂F₁到BC₃F₁单株内的供体染色体片段数减少了57.6%;BC₂F₁世代单株内的供体染色体片段长度平均为99.3 cM,BC₃F₁世代为87.1 cM,BC₃F₁较BC₂F₁减少了12.3%;BC₂F₁世代单株内的供体基因组大小平均为1 132.8 cM,BC3F1世代为421.4 cM,BC₃F₁较BC₂F₁减少了62.8%。     

玉米雌穗一节多穗性状的遗传研究

以玉米自交系XL21和PH6WC组成的6世代群体为材料,调查各群体同一穗位处果穗数量。利用P₁、P₂、F₁、F₂、BC₁和BC₂多世代联合分析法,研究控制玉米一节多穗性状的基因分离规律。结果表明,该性状在F₂分离世代表现为斜率负值的直线分布,BC₁群体主要呈类似于偏正态分布,BC₂群体呈类似于反比例函数分布。通过群体AIC值进行适合性检验,该性状符合一对加-显主基因+加-显-上位性多基因遗传D模型,主基因效应大于多基因效应,且加性效应大于显性效应,主基因遗传率为49.5%～60.2%,多基因遗传力为27.4%～41.1%,两者累加贡献率达到87.6%～90.6%。控制玉米一节多穗性状以加性效应为主,在遗传育种中针对该性状对早代试材进行重点选择和淘汰。     

玉米辽综群体创建、改良及应用研究

以引自美国和选自美国血缘的自交系为基础材料,组建玉米辽综群体。采用S₁表型选择法、S₁家系密植鉴定选择法、配合力选择法对玉米辽综群体进行3轮改良,系统评价8个改良群体的育种潜势。结果表明,S₁家系密植鉴定选择法改良群体效果显著,且方便、实用。以密植鉴定选择法改良的群体辽综C_3-3穗行数增加明显、产量性状GCA水平较高、育种潜力较大。以其为基础群体,运用S1密植选择法结合新种质导入进行后续两轮改良。从不同轮次的改良群体中陆续选育出了6个优良玉米自交系,组配出6个相应的玉米杂交种通过国家或省级审定,新品种累计推广面积122.5万hm²。     

60Co γ辐射小麦M3代种子和幼苗抗旱性的变异

为了探讨利用物理诱变技术创制小麦抗旱种质资源的可行性,采用⁶⁰Coγ射线辐射诱变小麦品种涡9722,用30%PEG6000溶液模拟干旱胁迫,对227个M₃代株行进行发芽试验和幼苗生长试验,测定发芽指标和幼苗的生长指标、生理指标。结果表明,发芽势、发芽率、发芽指数、苗高、叶数、根数、主根长、根干重、地上部分干重、根冠比、根含水率、苗含水率、脯氨酸含量、可溶性糖含量、叶绿素含量等15个指标在M₃代株行间差异极显著。以综合抗旱系数评价抗旱性,M₃群体株行抗旱性的变异倾向于正偏态分布,抗旱性低于亲本的株行占61.2％,高于亲本的株行占38.8％。以超过M₃群体株行综合抗旱系数均值±2×标准差筛选变异株行,有9个株行发生正向变异,其中株行176的综合抗旱性表现突出,抗旱萌发和抗旱生长的能力均较好。用类平均法对227个M₃代株行进行聚类,当遗传距离为1.59时,M₃代株行的抗旱性变异类型可分为6大类。     

玉米耐旱相关基因dbf1的序列变异分析

玉米dbf1 基因在干旱胁迫下的编码产物与DIP₁蛋白相结合,调控植物激素脱落酸（ABA）响应基因rab17 的表达,从而提高耐旱性。以B73的dbf1 基因组序列为模板,对104个玉米自交系的dbf1 基因进行测序,研究玉米dbf1 基因的序列多态性。多态性分析表明,在全长为2 118 bp的序列中共发现48个SNP和12个InDel。尽管大部分变异位点集中在非编码区,但编码区的1个InDel和3个非同义突变位点的变异可以产生氨基酸序列改变。玉米dbf1 基因的全长序列和编码区序列的变异位点可以分别将该基因划分成33和11种单倍型,并且编码7种蛋白质。在供试材料中,dbf1 基因至少经历了9次重组,中性检测表明,该基因的进化没有偏离中性选择。     

Production of Raphanus sativus (C3)-Moricandia arvensis (C3-C4 intermediate) Monosomic and Disomic Addition Lines with Each Parentl Cytoplasmic Background and their Photorespiratory Characteristics

Abstract

We are maintaining five Moricandia arvensis monosomic addition lines of Raphanus sativus carrying R. sativus cytoplasm (autoplasmic MALs) and twelve M. arvensis MALs of R. sativus carrying M. arvensis cytoplasm (alloplasmic MALs) from BC₆ to BC₈ generation, and newly produced five M. arvensis disomic addition lines of R. sativus (autoplasmic DALs) and seven M. arvensis DALs of R. sativus carrying M. arvensis cytoplasm (alloplasmic DALs) from selfing and sib-crossing of the MALs and DALs in S₃BC₅ and S₂BC₆ generations. The structural, biochemical and physiological characteristics related to photorespiration of these MALs and DALs were compared to study the genetic mechanisms of the C₃-C₄ intermediate photosynthesis in the individual chromosomes of M. arvensis. The CO₂ compensation point of the autoplasmic and alloplasmic DALs (RMa-b and MaR-b DALs) with one pair of M. arvensis ‘b’ chromosome were 29.4 and 30.1 μmol mol-¹, respectively, which were significantly lower than that of other DALs and MALs as well as R. sativus (34.5 𰂼mol mol-¹). An immunogold electron microscopic study of the P-protein of glycine decarboxylase (GDC) in photosynthetic cells of the RMa-b DAL revealed that the bundle sheath cell (BSC) mitochondria were more intensively labeled for the protein than the mesophyll cell (MC) mitochondria. The ratio of the labeling density of the BSC mitochondria to that of the MC mitochondria was 1.13, which lies between values in M. arvensis (2.66) and R. sativus (0.76). These data suggest that the ‘b’ chromosome of M. arvensis genome controls the expression of C₃-C₄ intermediate characteristics.     

Improvement of rice drought tolerance through backcross breeding: Evaluation of donors and selection in drought nurseries

A large-scale backcross breeding project has been undertaken to improve drought tolerance in rice. Over 160 donor cultivars from 25 countries have been used in this project, representing a significant proportion of the genetic variation in cultivated rice. These cultivars were evaluated in field experiments in the Philippines to assess their responses to drought in terms of plant height, heading date, and grain yield. Drought was imposed near heading stage, in experiments that were established either in lowland (anaerobic) fields or upland (aerobic) soil. Despite the poor adaptation of some cultivars to the tropics, it was possible to identify significant variation in plant response to drought treatments, and contrasting effects on flowering delay and growth. Subsequently, 325 BC₂F₂ bulk populations, developed by backcrossing many of these donors to one of three elite recurrent parents, were screened under drought in lowland or upland nurseries. Stress levels were managed to eliminate almost all seed set in recurrent parents, and those progeny that produced grain were selected as being putatively drought-tolerant. The selection intensity varied across years and in selection environments with more severe stress, higher selection intensity could be imposed. The number of plants selected within a population was not associated with the per se drought response of the donors in the direct evaluation, indicating the wide presence of cryptic genetic variation for drought tolerance in the apparently drought-susceptible cultivars. The genetic background of the recurrent parent affected the number of plants selected, as did the selection environment (upland versus lowland nurseries). These drought-selected introgression lines represent a useful genetic resource to develop improved cultivars for farmers in rainfed or water-scarce rice-growing regions, and also to improve our understanding of the genetic and molecular basis of drought tolerance in rice. Genetic analysis of the selected lines, reported elsewhere, indicated specific regions of high introgression. Yield evaluations of the selected lines are now underway across a range of drought scenarios.     

The importance of the anthesis-silking interval in breeding for drought tolerance in tropical maize

Selection for improved performance under drought based on grain yield alone has often been considered inefficient, but the use of secondary traits of adaptive value whose genetic variability increases under drought can increase selection efficiency. In the course of recurrent selection for drought tolerance in six tropical maize (Zea mays L.) populations, a total of 3509 inbred progenies (S₁ to S₃ level) were evaluated in 50 separate yield trials under two or three water regimes during the dry winter seasons of 1986–1990 at Tlaltizapán, México. In over 90% of the trials, ears plant⁻¹, kernels plant⁻¹, weight kernel⁻¹, anthesis-silking interval (ASI), tassel branch number and visual scores for leaf angle, leaf rolling and leaf senescence were determined. Low scores indicated erect, unrolled or green leaves. Canopy temperature, leaf chlorophyll concentration and stem-leaf extension rate were measured in 20–50% of the trials. Across all trials, linear phenotypic correlations (P < 0.01) between grain yield under drought and these traits, in order listed, were 0.77, 0.90, 0.46, −0.53, −0.16, 0.06^NS, −0.18, −0.11, −0.27, 0.17 and 0.10. Genetic correlations were generally similar in size and sign. None of physiological or morphological traits indicative of improved water status correlated with grain yield under drought, although some had relatively high heritabilities. Genetic variances for grain yield, kernels ear⁻¹, kernels plant⁻¹ and weight kernel⁻¹ decreased with increasing drought, but those for ASI and ears plant⁻¹ increased. Broad-sense heritability for grain yield averaged around 0.6, but fell to values near 0.4 at very low grain yield levels. Genetic correlations between grain yield and ASI or ears plant⁻¹ were weak under well-watered conditions, but approached −0.6 and 0.9, respectively, under severe moisture stress. These results show that secondary traits are not lacking genetic variability within elite maize populations. Their low correlation with grain yield may indicate that variation in grain yield under moisture stress is dominated by variation in ear-setting processes related to biomass partitioning at flowering, and much less by factors putatively linked to crop water status. Field-based selection programs for drought tolerance should consider these results.     

Glu A1和 Glu D1位点高分子量谷蛋白亚基共同缺失对弱筋小麦品质的影响

为了研究高分子量谷蛋白亚基(HMWGS)缺失对小麦品质的影响,以 GluA1和 GluD1位点HMWGS共同缺失材料2GS041410作供体亲本,以弱筋小麦品种扬麦13和扬麦18作轮回亲本进行回交,构建不同遗传背景的BC¹F³和BC²F³群体,测定受体、供体亲本的品质,以及回交群体BC¹F³和BC²F³中 GluA1和 GluD1位点HMWGS共同缺失纯合单株及两位点均正常表达纯合单株的品质。结果表明,供体2GS041410具有较低的SDS沉降值、较短的面团形成时间和稳定时间;在BC¹F³和BC²F³中, GluA1和 GluD1位点HMWGS共同缺失对蛋白含量影响不显著,但可显著或极显著降低SDS沉降值和水溶剂保持力(SRC)。 GluA1和 GluD1位点HMWGS双缺失在弱筋小麦品质育种中具有一定的应用价值。     

玉米耐旱相关候选基因dhn2的等位变异与表型性状的关联分析

以95份玉米核心自交系组成的关联作图群体为试验材料,进行耐旱相关候选基因dhn2(编码脱水素蛋白)的序列多样性和连锁不平衡结构分析,挖掘不同种质资源中的等位变异。在考虑群体结构影响的基础上,进行dhn2基因多样性与耐旱相关表型之间的关联分析。结果表明：该基因编码区序列多样性较高,但LD水平较低,并检测出7个多态性位点与表型性状显著关联。     

Mechanism of High Photosynthetic Capacity in BC2F4 LinesDerived from a Cross between Oryza sativa and Wild Relatives O. rufipogon

Abstract

We found that several BC₂F₄ lines had high leaf photosynthetic rates under light-saturated and ambient CO₂ conditions. These lines are progenies of BC₂F₁ plants with high photosynthetic capacities which were generated by backcrossing between Oryza rufipogon (W630) and O. sativa cv. Nipponbare, as a recurrent parent. Some photosynthetic characteristics of the BC₂F₄ lines were investigated to identify the factors increasing photosynthetic rates. Photosynthetic rates of these lines under light-saturated conditions at 50 to 700 ppm CO₂ concentrations were higher than those in Nipponbare. The estimated-maximum photosynthetic rates under light-saturated and CO₂-saturated conditions in BC₂F₄ lines were also higher than that in Nipponbare. The photosynthetic rate under light-saturated and ambient CO₂ conditions was positively correlated with the carboxylation efficiency as an indicator of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) activity in vivo rather than stomatal conductance. Initial and total Rubisco activities in vitro tended to be higher in the BC₂F₄ lines than in Nipponbare. The content of active Rubisco calculated from the activation state of Rubisco was also higher in the BC₂F₄ lines than in Nipponbare. These results suggest that high photosynthetic capacities of BC₂F₁ plants can be maintained high in their progenies and high photosynthetic rates under light-saturated and ambient CO₂ conditions in the BC₂F₄ lines are achieved mainly by the high activity of Rubisco due to the high active Rubisco content.     

玉米低钾耐性性状的主基因+多基因遗传分析

应用植物数量性状主基因+多基因混合遗传模型多世代联合分析方法,以玉米缺钾症状叶片数为指标,对1个耐低钾玉米自交系T和2个低钾敏感玉米自交系S1和S2配制成的2个组合的P1、P2、F1、B1、B2和F2世代进行遗传分析,研究明确玉米耐低钾性状的遗传机制。结果表明,玉米低钾耐性遗传在2个组合中都由1对加性+加性-显性多基因控制;主基因遗传率(F2)平均为60.43%,多基因遗传率(F2)平均为15.35%;T×S1组合的遗传变异占表型变异值为80.20%,T×S2组合的遗传变异占表型变异值为71.35%,表明耐低钾性状以主基因遗传为主。育种应用上可以在低世代进行这一目标性状的选择。     

Modeling groundnut (Arachis hypogaea L.) performance under drought conditions

Erratic rainfall is often a limiting factor in the semi-arid regions where most groundnut cultivation occurs. As a result, ensuring availability of cultivars that possess inherent tolerance to drought stress has become a priority. Field and box (wooden boxes of 2 m length × 1 m width × 0.3 m depth) experiments were conducted under drought and non-drought conditions to identify physiological and agronomic traits correlated with pod yield (PY). Fifty (50) advanced breeding lines were evaluated. Linear models containing different combinations of total dry matter at maturity, crop growth rate, pod growth rate, partition coefficient, and harvest index were able to predict PY under intermittent drought (adjusted R² range: 0.9798–0.9895). The box experiment was more discriminating of genotypes than field experiments, making it a suitable technique for drought tolerance screening using specific leaf area and leaf chlorophyll content. As a result, screening and pre-selection using the seed-box technique before advanced evaluation on the field is recommended.     

Transgressive variants for red pericarp grain with high yield potential derived from Oryza rufipogon × Oryza sativa: Field evaluation, screening for blast disease, QTL validation and background marker analysis for agronomic traits

Five transgressive variants (advanced breeding lines from BC₂F₅ and BC₂F₆ generation) were derived from a cross between the wild relative, O. rufipogon Griff. and O. sativa L. subsp. indica cv. MR219, a popular high yielding Malaysian rice cultivar. The aim of the study was to evaluate the pericarp colour of the grains along with yield potential and to validate quantitative trait loci (QTLs) for agronomic traits. The variants were screened against blast disease. Background marker analysis was also done for the promising variants. The field trials were carried out at a single location (due to containment purposes) over two seasons using randomized complete block design (RCBD) with three replications. A trait-based marker analysis was used to identify QTLs for validation in BC₂F₅ generation. Analysis of variance (ANOVA) showed that the seasonal factors influenced different agronomic traits. Variant G33 produced significantly (p < 0.05) higher yield (5.20 t/ha) than the control, MR219 (4.53 t/ha). Eighteen QTLs for different agronomic traits were identified in BC₂F₂ population in a previous study. Among them 14 QTLs were found in BC₂F₅ population of the present study. The yield of variant G33 was influenced by several QTLs viz. qGPL-1, qSPL-1-2, qSPL-8 and qYLD-4, which were introgressed from the donor parent revealed by background marker analysis using BC₂F₇ generation. Percentage (99%) of red pericarp grain of G33 and G34 in BC₂F₅ and BC₂F₆ generations indicated the stability of pericarp colour which was transferred from the wild relative. Variant G33 showed resistance against two pathotype of blast disease (Magnaporthe oryzae). Among the evaluated variants, G33 could be considered for inclusion in the cultivar development program for red rice with high yield potential and resistance to blast disease. This study demonstrated that the alleles from wild relative could improve the yield and yield related traits through allelic interaction, even though the phenotypic traits were inferior to the recurrent parent.