甘蓝型油菜种子发芽率QTL定位及相关生理性状

利用GH06×P174组合衍生的183个重组自交系进行种子发芽率遗传分析及种子发芽期间种子生理性状分析。用复合区间作图法对在室温下保存两年的种子(STY)、保存1年的种子(SOY)与新收获种子(FS)发芽率进行QTL定位。另外对保存两年的种子及新收获的种子萌发期间脂肪酶活性、电导率、还原糖含量、总糖含量及根系活力进行了测定, 并对结果进行分析。结果表明3批种子的发芽率QTL位点各不相同, 保存两年的种子在第9、14、17条连锁群上分别检测到1个位点, 保存1年的种子在第5、9条连锁群上各检测到1个位点, 新收获的种子在第4、18条连锁群上分别测检到1个位点。研究发现, 3批种子的发芽率相关性不显著, 发芽率差异达到极显著水平, 同时保存不同年份种子的发芽率QTL各不相同, 这表明甘蓝型油菜发芽率受很多不同因素所控制。保存两年及新收获种子的发芽率与电导率之间的相关性均达到极显著负相关, 表明可以通过电导率的测定估测发芽率, 电导率的研究对种子发芽率的研究具有重要意义。     

豌豆遗传图谱构建及QTL定位研究进展

豌豆的许多性状是多基因控制的数量性状,QTL定位就是以分子标记技术为工具、以遗传连锁图谱为基础、利用分子标记与QTL之间的连锁关系确定控制数量性状的基因在基因组中的位置.本文对QTL定位原理、方法进行了简单介绍;对豌豆遗传图谱构建及主要性状,如产量、品质、抗病性等QTL定位、遗传效应分析等方面的研究进行综述;对目前基于QTL豌豆分子标记育种存在的问题、应用前景进行了探讨.     

水稻光合功能相关性状QTL分析

利用粳稻Kinmaze／籼稻DV85杂交后代单粒传衍生的81个F11家系所组成的重组自交系（Recombinant Inbred Lines,RILs）群体,研究水稻光合功能相关性状的数量性状基因座（QTL）。在水稻抽穗后7d测定叶片全氮含量（TLN）、叶绿素a／b比值（Chl．a：b）和叶绿素含量（Chl）。共检测到6个QTL,各QTL的LOD值为2．66～4．81,贡献率为11．2％-29．6％,其中,在第1、2和11染色体上检测到3个与全氮含量相关的QTL,相应贡献率为17．3％、15．3％、13．7％;在第3和4染色体检测到2个与叶绿素a／b比值相关的QTL,贡献率为13．8％和29．6％;在第1染色体检测到1个与叶绿素含量相关的QTL,贡献率为11．2％。4个QTL为本研究新检测的基因座。有趣的是,控制叶绿素含量的qCC-1位于第1染色体上RFLP标记C122附近,与已报道的NADH-谷氨酸合成酶基因位置一致,而叶绿素合成始于谷氨酸,暗示该基因座与水稻光合功能关系极为密切。然而,对抽穗后30d叶绿素含量进行QTL分析,结果未检测到与其相关的QTL,表明控制叶绿素含量qCC-1效应随水稻叶片的衰老而降低。     

植物数量性状基因定位研究概述

植物重要的性状多为数量性状。长期以来,人类一直寻求解释植物数量性状的遗传规律以便对其进行遗传操纵。现代分子生物技术的发展为植物数量性状基因的定位、分离等研究提供了条件。本文从数量性状基因座(QTL)作图群体类型及其特点,QTL定位方法,植物QTL研究现状,以及QTL精细定位、克隆、利用等方面进行了综述,并对今后植物QTL研究进行了展望。     

数量性状基因座位及其在家禽中的定位

近年来随着现代分子生物学的发展 ,一些高效的分子遗传标记将各种畜禽的遗传图谱研究推向深入。为高密度、覆盖面广的连锁图谱的构建及QTL的定位奠定了基础。有关QTL的基本理论、QTL定位的步骤、QTL的检测方法以及家禽中定位的QTL已经展开了深入的研究 ,但目前QTL定位中存在诸多问题的问题     

水稻蒸煮品质相关QTL定位及候选基因分析

挖掘与稻米蒸煮品质相关的数量性状基因座(quantitative trait locus, QTL),分析候选基因,并通过遗传育种手段改良稻米蒸煮品质相关性状,可有效提升稻米的口感。以籼稻华占(Huazhan, HZ)、粳稻热研2号(Nekken2)及由其构建的120个重组自交系(recombinant inbred lines, RILs)群体为实验材料,测定成熟期稻米的糊化温度(gelatinization temperature, GT)、胶稠度(gel consistency, GC)和直链淀粉含量(amylose content, AC)。结合高密度分子遗传图谱进行QTL定位,共检测到26个与稻米蒸煮品质相关的QTLs (糊化温度相关位点1个、胶稠度相关位点13个、直链淀粉含量相关位点12个),其中最高奇数的可能性(likelihood of odd, LOD)值达30.24。通过实时荧光定量PCR (quantitative real-time polymerase chain reaction, qRT-PCR)分析定位区间内候选基因的表达量,发现6个基因在双亲间的表达量差异显著,推测LOC_Os04g20270和LOC_Os11g40100的高表达可能会极大地提高稻米的胶稠度,而LOC_Os01g04920和LOC_Os02g17500的高表达以及LOC_Os03g02650和LOC_Os05g25840的低表达有助于降低直链淀粉含量。这些结果为培育优质水稻新品种奠定了分子基础,并为揭示稻米蒸煮品质的分子调控机制提供了重要的遗传资源。     

水稻产量相关QTL研究现状

产量是最为复杂的数量性状,对它的遗传机理了解甚微。近15年来,许多学者利用随机分离群体定位了许多影响水稻产量及其组分的QTL,即以QTL定位的方法对产量潜力进行遗传剖析。试验证明上位性效应对产量及其组分性状遗传变异起着重要作用,但目前大多数QTL研究仍侧重于发掘和克隆单个主效QTL,然而对单一基因／QTL的深入了解还不足以诠释复杂性状遗传基础的全貌,还没有为育种家提供足够的可应用于分子标记辅助育种的遗传信息并用于提高水稻产量。笔者认为今后的数量性状研究尚需加强复杂性状QTL遗传网络的发掘,在改良水稻品种性状的同时发展并完善QTL研究。     

鲤鱼体长性状的QTL定位及其遗传效应分析

以大头鲤/荷包红鲤抗寒品系的重组自交系群体及其遗传连锁图谱, 利用Windows Map Manager 2.0的标记回归法进行QTL单标记定位分析和复合区间作图法进行QTL区间检测, 通过置换实验(1 000次重复)确定连锁群显著性水平阈值。在体长性状的标记回归研究中, 共7个标记达到显著水平(P<0.01), 对性状的贡献率为14.00%～27.00%, 其中3个标记达到极显著水平(P<0.001)。HLJ534, HLJ319, HLJ370座位可能与影响鲤鱼体长性状的主效基因连锁。在体长性状的QTL区间定位研究中, 共6个QTL达到连锁群显著水平(P=0.05), 对性状的贡献率为11.33.%～23.12%, 其中2个达到连锁群极显著性水平(P=0.01), 它们的加性效应方向并不一致。HLJ190-HLJ497区间和HLJ479-HLJ483区间是影响鲤鱼体长性状的主效QTL区间。     

大豆耐旱种质鉴定和相关根系性状的遗传与QTL定位

从301份黄淮海和长江中下游地区代表性大豆地方品种和育成品种(系)中按根系类型选取59份,在苗期干旱胁迫和非胁迫条件下对地上部和地下部性状进行2年重复鉴定,发现材料间性状隶属函数值具有丰富遗传变异,以株高、叶龄、根干重和茎叶干重隶属函数的算术平均数为抗旱综合指标从中筛选出汉中八月黄、晋豆14,科丰1号,圆黑豆等强耐旱型(1级)和临河大粉青、宁海晚黄豆等干旱敏感型(5级)材料。比根干重、比总根长、比根体积与耐旱隶属函数平均值均呈极显著正相关,可作为耐旱性的根系性状指标。利用“科丰1号×南农1138 2”(1级×4级)衍生的RIL群体为材料,对耐旱相关根系性状采用主基因 多基因混合遗传模型分离分析法进行遗传分析并进行QTL定位。结果表明,该两亲本间比根干重、比总根长、比根体积的遗传均为两对主基因加多基因模型,后两者主基因间有连锁(重组率分别为4.30%和1.93%);主基因遗传率为62.26%～91.81%,多基因遗传率为2.99%～24.75%;耐旱相关根系性状各主要由1对主基因控制,另1对效应较小。QTL分析检测到5、3、5个QTLs分别控制比根重、比根总长、比根体积,位于N6 C2、N8 D1b W、N11 E、N18 K连锁群上。3性状各有1个贡献率大的QTL(Dw1,Rl1,Rv1),而且均位在N6 C2的STAS8_3T STAS8_6T相同距离的区段上,其他QTLs效应均较小。分离分析与QTL定位的结果相对一致。     

水稻穗部性状的QTL与环境互作分析

分别在两年收集珍汕97／明恢63的重组自交系群体的表现数据,运用混合线性模型的QTL定位方法,联合分析穗部5个性状的QTLs7及QTL与环境互作关系。每穗颖花数、每穗实粒数、结实率、穗长和穗着密度分别检测到10、3、6、8和7个QTLs分别解释各性状变异的29．13％、19．2％、29．46％、26．39％和35．76％。对于同一性状,高值亲本和低值亲本中均存在增效和减效QTL。相关性状QTL的位置表现相同或相似,高值亲本和低值亲本中均存在增效和减效QTL。相关性状QTL的位置表现相同或相似,成族分布。1个穗长QTL,2个每穗颖花数QTL3,3个结实率QTLs表现与环境显著互作,QTL与环境互作效应的贡献率比相应的QTL贡献率略大。遗传力稍高的每穗实粒数和穗着粒密度的DQTL与环境不互作。     

Evolution of correlated characters

Many traits are genetically correlated with each other. Thus, selection that changes the mean value of one trait causes other traits to change as well. Recent comparative studies have emphasized the possible importance of such correlated responses in affecting the evolution of traits, including some behaviors, which are of little adaptive significance, or even maladaptive. However, it is also possible for traits with major effects on fitness, such as brain size, to evolve entirely by correlated response. Other traits that do not appear to have evolved at all may have been subject to much directional selection, simply to prevent their evolution by correlated response. The new interest in correlated responses reflects more rigorous attempts to consider the organism as a whole, rather than dissecting it into a number of questionably separable traits.     

Malate plays a crucial role in starch metabolism, ripening, and soluble solid content of tomato fruit and affects postharvest softening

Despite the fact that the organic acid content of a fruit is regarded as one of its most commercially important quality traits when assessed by the consumer, relatively little is known concerning the physiological importance of organic acid metabolism for the fruit itself. Here, we evaluate the effect of modifying malate metabolism in a fruit-specific manner, by reduction of the activities of either mitochondrial malate dehydrogenase or fumarase, via targeted antisense approaches in tomato (Solanum lycopersicum). While these genetic perturbations had relatively little effect on the total fruit yield, they had dramatic consequences for fruit metabolism, as well as unanticipated changes in postharvest shelf life and susceptibility to bacterial infection. Detailed characterization suggested that the rate of ripening was essentially unaltered but that lines containing higher malate were characterized by lower levels of transitory starch and a lower soluble sugars content at harvest, whereas those with lower malate contained higher levels of these carbohydrates. Analysis of the activation state of ADP-glucose pyrophosphorylase revealed that it correlated with the accumulation of transitory starch. Taken together with the altered activation state of the plastidial malate dehydrogenase and the modified pigment biosynthesis of the transgenic lines, these results suggest that the phenotypes are due to an altered cellular redox status. The combined data reveal the importance of malate metabolism in tomato fruit metabolism and development and confirm the importance of transitory starch in the determination of agronomic yield in this species.     

Dynamic QTL analysis of linolenic acid content in different developmental stages of soybean seed

Linolenic acid (LN) in soybean (Glycine max L. Merr.) seed mainly contributes to the undesirable odors and flavors commonly associated with poor oil quality. LN deposition at various stages of soybean seed development had not been reported by 2010. The objects of this study were (1) to identify and measure quantitative trait loci (QTL) underlying LN content and (2) to estimate the QTL effects expressed from earlier seed developmental stages to drying seed of soybean. One hundred and twenty-five F_5:8 and F_5:9 recombinant inbred lines derived from the cross of soybean cultivars ‘Hefeng 25’ and ‘Dongnong L5’ were used for the identification of QTL underlying LN content from the 37 day (D) to 86D stages after flowering, at Harbin in 2008 and 2009. QTL × Environment interactions (QE) effects were evaluated using a mixed genetic model (Zhu in J Zhejiang Univ (Natural Science) 33:327–335, 1999). Twelve unconditional QTL and 12 conditional QTL associated with LN content were identified at different developmental stages. Most of the QTL explained <10% of phenotypic variation of LN content. Unconditional QTL QLNF-1, QLNC2-1, QLND1b-1, QLNA2-1 and QLNH-1 influenced LN content across different development stages and environments. Conditional QTL QLNF-1, QLNC2-1 and QLNH-1 were identified in multiple developmental stages and environments. Conditional and unconditional QTL clustered in neighboring intervals on linkage groups A2, C2 and D1b. Ten QTL with conditional additive main effects (a) and/or conditional additive × environment interaction effects (ae) at specific developmental stage were identified on nine linkage groups. Of them, six QTL only possessed additive main effects and seven QTL had significant ae effects in different developmental stages. A total of 13 epistatic pairwise QTL were identified by conditional mapping in different developmental stages. Two pairs of QTL only showed aa effects and five pairs of QTL only showed aae effects at different developmental stages. QTL with aa effects, as well as their environmental interaction effects, appeared to vary at different developmental stages.     

Identification of the quantitative trait loci (QTL) underlying water soluble protein content in soybean

Water soluble protein content (SPC) plays an important role in the functional efficacy of protein in food products. Therefore, for the identification of quantitative trait loci (QTL) associated with SPC, 212 F_2:9 lines of the recombinant inbred line (RIL) population derived from the cross of ZDD09454 × Yudou12 were grown along with the parents, in six different environments (location × year) to determine inheritance and map solubility-related genes. A linkage map comprising of 301 SSR markers covering 3,576.81 cM was constructed in the RIL population. Seed SPC was quantified with a macro-Kjeldahl procedure in samples collected over multiple years from three locations (Nantong in 2007 and 2008, Zhengzhou in 2007 and 2008, and Xinxiang in 2008 and 2009). SPC demonstrated transgressive segregation, indicating a complementary genetic structure between the parents. Eleven putative QTL were associated with SPC explaining 4.5–18.2 % of the observed phenotypic variation across the 6 year/location environments. Among these, two QTL (qsp8-4, qsp8-5) near GMENOD2B and Sat_215 showed an association with SPC in multiple environments, suggesting that they were key QTL related to protein solubility. The QTL × environment interaction demonstrated the complex genetic mechanism of SPC. These SPC-associated QTL and linked markers in soybean will provide important information that can be utilized by breeders to improve the functional quality of soybean varieties.     

Cranial shape and correlated characters in crocodilian evolution

Crocodilians show a high degree of cranial variation and convergence throughout their 80 million-year fossil record that complicates their phylogenetic reconstruction. Conflicting phylogenetic results from different data partitions and character homoplasies typify crocodilian phylogeny, and differences between molecular and morphological phylogenetic hypotheses are believed to be associated with the slender-snout skull shape of Gavialis gangeticus and Tomistoma schlegelii. Slender-snout skulls are one of five identified eusuchian cranial ecomorph shape categories (ESCs) thought to reflect functional or ecological specialization. This paper tested the effect of transitions among general, blunt and slender ESCs on cranial character-state distributions in phylogeny using the concentrated changes test. In addition, 'tree-free' character compatibility analysis of character independence was conducted on the morphological character matrix to determine if character correlations are observed independent of specific tree topologies. Results suggest cranial ESCs do affect cranial character-state gains in phylogeny. Concentrated changes identify a broad suite of character-state changes that significantly correlate with transitions to slender, general and blunt ESCs on morphological, molecular and combined-data tree topologies, but numbers of correlated characters for each category differ according to topology. Character compatibility analysis results do not mirror the concentrated changes test results and reflect hierarchically distributed support throughout the data. As cranial ESCs affect character-state transitions, it is possible that nonphylogenetic variables could affect inferences of crocodilian phylogeny by affecting cranial morphology.     

Identification of restriction fragment length polymorphisms linked to genes controlling soluble solids content in tomato fruit

Summary Gene(s) conferring high soluble solids (SS) in tomato fruit had been backcrossed previously from a wild tomato species, Lycopersicon chmielewskii LA1028 ( 10% SS), into a L. esculentum cultivar, VF36 ( 5% SS), to derive a BC₅S₅ line, LA1563, similar to VF 36 but with 7–8% SS. DNAs from these lines and a tomato breeding line, H2038, were screened for restriction fragment length polymorphisms (RFLPs) using four restriction endonucleases and sixty clones chosen at random from a tomato cDNA library. Most of the cDNA clones (56) identified the same RFLP in VF 36 and LA1563 and a different RFLP in LA1028. However, two cDNA clones identified the same RFLP in LA1563 and LA1028 and a different RFLP in VF36. To determine whether RFLPs identified by these two cDNA clones were linked to SS genes, a H2038 x LA1563 F₂ population was screened for segregation of the RFLPs and for SS content. The segregation ratios of these RFLPs were consistent with ratios expected for codominant alleles at unlinked loci. Analysis of variance of SS content for different RFLP genotypic classes indicated that RFLP alleles at one of the loci were linked to genes controlling SS content. The RFLP allele from the high SS tomato line, LA1563, was associated with significantly higher SS content and, therefore, could be useful in selecting for high SS gene(s) in a tomato breeding program.     

QTL analysis of morphological traits in a tomato recombinant inbred line population.

Quantitative trait loci (QTLs) influencing morphological traits were identified by restriction fragment length polymorphism (RFLP) analysis in a population of recombinant inbred lines (RILs) derived from a cross of the cultivated tomato Lycopersicon esculentum with a related wild species, Lycopersicon cheesmanii. One hundred and thirty-two RFLP loci spaced throughout the tomato genome were used as DNA probes on genomic DNA from 97 RIL families. Morphological traits, including plant height, plant fresh mass, number of branches, number of nodes, first flower-bearing node, and leaf length, were evaluated in two controlled environment trials in 1992 and 1993. QTLs were detected via regression analyses at multiple marker loci for each morphological trait. A total of 41 markers were significantly associated with the traits examined. Large additive effects were measured at many of these loci. QTLs for multiple traits were detected on chromosomes 3 (TG74) and 4 (CT188), suggesting the possible association of these chromosome segments with genes controlling growth and development in tomato. These chromosomal regions were also associated with multiple morphological traits in a L. esculentum x Lycopersicon pennellii cross. A total of 13% of the QTLs identified for traits common to both studies occupied similar map positions.     

Genetics of drought tolerance during seed germination in tomato: inheritance and QTL mapping.

A BC1 population (N = 1000) of an F1 hybrid between a stress-sensitive Lycopersicon esculentum breeding line (NC84173; maternal and recurrent parent) and a germination stress-tolerant Lycopersicon pimpinellifolium accession (LA722) was evaluated for seed germination rate under drought stress (DS) (14% w/v polyethyleneglycol-8000, water potential approximately -680 kPa), and the most rapidly germinating seeds (first 3% to germinate) were selected. The 30 selected BC1 seedlings were grown to maturity and self pollinated to produce BC1S1 progeny seeds. Twenty of the 30 selected BC1S1 progeny families were evaluated for germination rate under DS and their average performance was compared with that of a "nonselected" BC1S1 population of the same cross. Results indicated that selection for rapid germination under DS significantly improved progeny germination rate under DS (selection gain = 19.6%), suggesting a realized heritability of 0.47 for rate of germination under DS in this population. The 30 selected BC1 plants were subjected to restriction fragment length polymorphism (RFLP) analysis, and marker allele frequencies for 119 RFLP markers which spanned 1153 cM of the 12 tomato chromosomes were determined. A distributional extreme marker analysis, which measures statistical differences in marker allele frequencies between a selected and a nonselected population, detected four quantitative trait loci (QTLs) for rate of germination under DS in this population. Of these, two QTLs, located on chromosomes 1 and 9, were contributed by the L. pimpinellifolium donor parent and had larger effects than the other two QTLs, located on chromosomes 8 and 12, which were contributed by the L. esculentum recurrent parent. A few BC1S1 families were identified with all or most of the identified QTLs and with germination rates comparable with that of LA722. These families should be useful for the development of germination drought-tolerant tomato lines using marker-assisted selection (MAS). The overall results indicate that drought tolerance during seed germination in tomato is genetically controlled and potentially could be improved by directional phenotypic selection or MAS.     

Interleukin-2 receptor positive cells and circulating soluble interleukin-2 receptors in patients with solid tumors are not correlated

Activated lymphocytes can release a soluble form of IL-2 receptor (sIL-2R), which retains the capacity to bind IL-2. Abnormally high values of sIL-2R have been observed in patients with advanced solid tumors. In an attempt to further understand the biological significance of sIL-2R in solid tumors, this study investigated the relation between sIL-2R and Tac-positive cells. sIL-2R serum levels and Tac-positive cells were determined in 18 patients with solid tumors metastatic, 108 non-metastatic. Tumor types were: breast 7; lung 6; colon 2; stomach 1; testis 1; larynx 1. No correlation was found between circulating sIL-2R values and Tac-positive cells, and there was no difference between Tac-positive cell mean number in patients with high and normal sIL-2R levels. These preliminary results suggest that different mechanisms are responsible for sIL-2R release in the blood and IL-2 receptor expression on the immune cell surface.