控制水稻剑叶形态相关性状的数量基因位点(QTL)的定位

水稻籽粒中一半以上的碳水化合物来自剑叶的光合作用,剑叶形态改良一直是水稻株型育种的一个重要目标．利用一个日本主要种植的粳稻品种越光（轮回亲本）和一个印度的籼稻品种Kasalath杂交产生的回交重组自交系群体（backcross recombinant inbred lines,BILs）对剑叶形态中的3个主要性状（剑叶长、叶宽以及其叶面积）进行了相关分析及其数量基因位点（quantitative trait loci,QTL）的定位．研究表明,控制剑叶形态的3个主要性状间存在极显著的正相关,并检测到影响3个性状的8个QTL,分布在第1,3,4,6条染色体上,贡献率介于4．94％～22．07％,其中第4染色体上C1016标记和第6染色体上C556标记附近的共有6个QTL,其两侧的紧密分子标记在水稻株型分子育种上具有一定应用价值．     

水稻苗期形态性状的QTL定位

采用苗期形态性状上有着明显差异的粳稻Asominori和籼稻IR24杂交产生的重组自交系（RILs）为材料,经营养液培养后,对水稻苗期形态相关的6个数量性状：最大根长（MRL）、苗高（SH）、根干重（RDW）、茎（叶）干重（SDW）、总重（TW）以及根/茎（叶）干重比（RSR）进行了数量性状位点（QTL）定位分析.结果共检测到影响6个形态性状的8个QTL位点,分别位于水稻的第2,4,10和11染色体上,其贡献率为9.79%～22.90%.并发现位于第4染色体上的控制根/茎（叶）干重比的qRSR-4和根干重的qRDW-4的2个位点以及位于第10染色体上的控制茎（叶）干重的qSDW-10和总重的qTW-10的2个位点分别位于同一分子标记区间.研究结果对水稻苗期形态性状QTL的精细定位及培育理想株型具有一定的应用价值.     

QTL mapping of the root traits and their correlation analysis with drought resistance using DH lines from paddy and upland rice cross

A Double Haploid (DH) population, 116 plants, derived from the cross between Japonica upland rice IRAT109 and paddy rice Yuefu, planted in PVC pipe under upland ecosystem in 2001 and 2002, was used in this study. Seven root traits, including basal root thickness (BRT), total root number (RN), maximum root length (MRL), root fresh weight (RFW), root dry weight (RDW), ratio of root fresh weight to shoot fresh weight (RFW/SFW) and ratio of root dry weight to shoot dry weight (RDW/SDW), were studied. Using index of drought resistance (IDR), the ratio of yield under upland ecosystem to yield under lowland ecosystem of DH lines, as the criteria of drought resistance, and correla-tion analysis between root traits and IDR, showed that BRT, MRL and RN were significantly correlated with IDR. High IDR lines had thicker BRT, longer MRL and less RN than low IDR lines. A molecular linkage map with 94 RFLP markers and 71 SSR markers covering 1535.1 cM was pro-duced. QTLs and G譋 interactions for BRT, RN, MRL, RFW, RDW, RFW/SFW and RDW/SDW were obtained based on the constructed molecular linkage map and soft-ware QTLmapper version 1.0. A total of 18 additive QTLs and 18 pairs of epistatic QTLs associated with root traits were detected. There were nine additive QTLs and two pairs of epistatic QTLs performed significant interactions with environment. Some QTLs with high general contribution and no G譋 interaction were obtained. Two pairs of epistatic QTLs mrl3 and mrl8, brt3 and brt11a controlling MRL and BRT had high general contributions of 21.51% and 13.03% respectively. An additive QTL and a pair of epistatic QTLs controlling RFW and RDW had high general contributions of 13.50% and 25.64% respectively. Marker assisted selec-tion (MAS) for rice drought resistance based on QTL with high general contribution, low G譋 interaction and tightly linkage with IDR were also discussed.     

Influence of outliers on QTL mapping for complex traits

A method was proposed for the detection of outliers and influential observations in the framework of a mixed linear model, prior to the quantitative trait locus （QTL） mapping analysis. We investigated the impact of outliers on QTL mapping for complex traits in a mouse BXD population, and observed that the dropping of outliers could provide the evidence of additional QTL and epistatic loci affecting the 1 stBrain-OB and the 2ndBrain-OB in a cross of the abovementioned population. The results could also reveal a remarkable increase in estimating heritabilities of QTL in the absence of outliers. In addition, simulations were conducted to investigate the detection powers and false discovery rates （FDRs） of QTLs in the presence and absence of outliers. The results suggested that the presence of a small proportion of outliers could increase the FDR and hence decrease the detection power of QTLs. A drastic increase could be obtained in the estimates of standard errors for position, additive and additive× environment interaction effects of QTLs in the presence of outliers.     

Starch RVA profile parameters of rice are mainly controlled byWx gene

Quantitative trait locus (QTLs) mapping for rapid visco analyser (RVA) profile parameters has been carried out by using a double haploid (DH) population derhred from a cross betweenindica variety Zhai-Ye-Qing 8 andjaponica variety Jing-Xi 17 and its genetic linkage map. The results indicate that the segregation of the RVA profiles is continually distributed among the DH lines, and some DH lines show transgressive segregation for all the parameters. A major QTL,Waxy (Wx) gene on chromosome 6 which controls the amylose synthesis, has been detected significantly for 5 traits: hot paste viscosity (HPV), cool paste viscosity (CPV), breakdown viscosity (BDV), consistency viscoslty (CSV) and setback viscoslty (SBV). Therefore, the RVA profile parameters are mainly controlled byWx gene. Other 3 and 2 QTLs have also been identified for BDV and SBV, respectively, and two of them share the same region on chromosomes 1 and 5. However, the peak viscosity (PKV) is controlled by a minor QTL on chromosome 12, qPKV-12.     

水稻芒长及其分布特征相关QTL的定位

水稻芒的性状与驯化过程密切相关,具体表现为芒长短和芒的分布等．利用一个无芒品种越光（轮回亲本）和一个有芒品种Kasalath杂交产生的回交重组自交系群体,在上海、海南两地对芒长和芒的分布（芒出现比例）进行了相关分析及其相关基因（QTL）定位,结果发现这两个性状间存在显著的正相关．共检测到影响这两个性状的12个QTL,分布在6条染色体上的7个区域,贡献率介于2．90％-53．24％,其正效应大多来自有芒亲本Kasalath,但也有3个QTL正效应来自无芒亲本越光,并对这个现象产生的原因进行了讨论．本研究检测到的QTL及其两侧的分子标记可以用于水稻驯化的研究和理想型无芒品种分子辅助育种．     

A genome scan for quantitative trait loci affecting grain yield and its components of maize both in single-and two-locus levels

Maize is one of the most important cereal crops in the world. The hybrid yield advantage is responsible for about 10 percent of the total global maize production of 550 Mt[1]. It is exigent to study the yield traits so as to improve the hybrids per se in …     

苗期低温锻炼对水稻叶片生理性状的影响

通过苗期亚低温的锻炼,研究水稻品种的诱导抗性.实验结果表明,与抗冷性弱的二九丰相比,抗冷性强的中冷8号通过亚低温锻炼,在叶绿素含量、叶片质膜透性、可溶性糖含量三个指标上表现出更强的抗低温能力.说明不同抗冷性的水稻品种具有不同的诱导抗性.     

数量性状基因座(QTL)定位的研究进展

对数量性状基因座 (QTL)的几种主要定位方法的统计学原理进行了综述 ,总结了每种方法的优缺点及其发展动态 ,特别是对新发展的多区间作图和多性状作图进行了较详细的介绍 ,并对目前存在的问题和今后的发展进行了讨论     

Fine mapping of <Emphasis Type="Italic">qHUS6.1</Emphasis>, a quantitative trait locus for silicon content in rice (<Emphasis Type="Italic">Oryza sativa</Emphasis> L.)

Silicon is essential for optimal growth of rice (Oryza sativa L.). This study was conducted to fine map qHUS6.1, a quantitative trait locus (QTL) for rice hull silicon content previously located in the interval RM510–RM19417 on the short arm of chromosome 6, and to analyze the effect of this QTL on the silicon content in different organs of rice. Selfed progenies of a residual heterozygous line of rice were detected using 13 microsatellite markers in the vicinity of qHUS6.1. Three plants with overlapping heterozygous segments were selected. Three sets of near isogenic lines (NILs) were developed from the selfed progenies of the 3 plants. They were grown in a paddy field and the silicon contents of the hull, flag leaf, and stem were measured at maturity. Based on analyses of the phenotypic distribution and variance among different genotypic groups in the same NIL set, a significant genotypic effect was shown in the NIL set that was heterogenous in the interval RM19410–RM5815, whereas a significant effect was not found in the remaining 2 NIL sets that were heterogenous in either of the intervals RM4923–RM19410 or RM19417–RM204. On comparison among the physical positions of the 3 heterogenous segments, qHUS6.1 was delimited to a 64.2-kb region flanked by RM19410 and RM19417 that contains nine annotated genes according to the genome sequence of Nipponbare. This QTL showed strong effects on all of the three traits tested, and the enhancing alleles were always derived from the paternal line Milyang 46. The present study will facilitate the cloning of qHUS6.1 and the exploration of new genetic resources for QTL fine mapping.     

Statistical approaches in QTL mapping and molecular breeding for complex traits

Most of the important agronomic traits in crops,such as yield and quality,are complex traits affected by multiple genes with gene × gene interaction as well as gene × environment interaction.Understanding the genetic architecture of complex traits is a long-term task for quantitative geneticists and plant breeders who wish to design efficient breeding programs.Conventionally,the genetic properties of traits can be revealed by partitioning the total variation into variation components caused by specific genetic effects.With recent advances in molecular genotyping and high-throughput technology,the unraveling of the genetic architecture of complex traits by analyzing quantitative trait locus (QTL) has become possible.The improvement of complex traits has also been achieved by pyramiding individual QTL.In this review,we describe some statistical methods for QTL mapping that can be used to analyze QTL × QTL interaction and QTL × environment interaction,and discuss their applications in crop breeding for complex traits.     

川中丘陵区4种乡土阔叶树细根性状对比研究

【目的】川中丘陵区的主要防护林分为柏木(Cupressus funebris)人工林,由于密度过大、树种单一,严重影响其综合效益的发挥。加上该区域土壤类型大多为紫色土,土层瘠薄、肥力低下,能够适应的树种不多。探明川中丘陵区带状补植的4种乡土阔叶树种[桤木(Alnus cremastogyne)、喜树(Camptotheca acuminata)、香樟(Cinnamomum camphora)、香椿(Toona sinensis)]的细根性状特征,了解它们对地下资源利用策略的种间差异,为该区域防护林树种的选择和经营提供依据。【方法】选择川中丘陵区“带状采伐+补阔”改造的人工柏木林分作为研究对象,对补植的林龄为7 a的4种乡土阔叶树——桤木、喜树、香樟、香椿,各选取5株长势均匀、良好的植株,采用“全株挖掘法”挖取其根系,研究其细根(直径<2 mm)的生物量、形态以及分支结构等性状特征。【结果】①桤木细根的生物量密度为(0.156±0.030) kg/m³,分别是喜树、香樟和香椿的15.67、11.72和4.61倍。桤木、喜树、香樟、香椿的细根表面积密度分别是0.99、0.45、0.68和1.13 m²/m³;根长密度分别是110.33、10.58、26.64和97.56 m/m³。②4种阔叶树细根的平均直径大小依次为喜树(1.67 mm)>香樟(1.06 mm)>香椿(0.77 mm) > 桤木(0.73 mm)。桤木、喜树、香樟、香椿的比根长和比表面积分别是62.54、49.31、81.53、287.50 cm/g和13.58、25.61、27.35、83.15 cm²/g。桤木的根组织密度显著高于其他3个树种(df=3, F=360.726, P<0.05)。③桤木的比根尖数、根尖密度、分枝密度分别为1 056个/g、2.37个/cm、2.65个/cm,均明显高于喜树、香樟、香椿3个阔叶树种(df=3,F=391.659,P<0.01;df=3,F=103.857, P<0.05;df=3,F=104.617, P<0.05)。④桤木细根中全氮含量分别比喜树、香樟、香椿高33.27%、88.65%、21.93%。香椿的全碳、全磷、全钾储量在4种树种中均最高。【结论】在带状采伐的前几年,由于采伐带内阳光充足,作为阳性树种的桤木和香椿,表现出强劲的竞争力,细根生物量密度较大。另一方面,改造初期,由于土层瘠薄,土壤水分含量较低,作为浅根性树种的桤木和香椿,通过增加水平根系的分支来获取更多的土壤空间从而吸收更多的营养,而香樟和喜树则通过增加细根直径和垂直深度来获取土壤空间,提高获取营养的能力。由此可见,川中丘陵区的4种阔叶树的细根性状具有明显差异,反映了不同的资源获取策略。     

应用RAPD标记构建马尾松单株树遗传连锁图谱

利用马尾松（Ｐｉｎｕｓｍａｓｓｏｎｉａｎａ）崇义群体Ｃ－１６号单株上４０粒种子的胚乳为作图群体材料，用随机扩增多态性ＤＮＡ（ＲＡＰＤ）方法构建马尾松单株遗传连锁图谱，从被步筛选的８０个引物中，得到１６个具有多态性产物的引物，对这１６种引物进行Ｍｅｎｄｅｌｉａｎ１：１分离检测（卡方检验，Ｐ＜０．０５），我们得到符合Ｍｅｎｄｅｌｉａｎ１：１分离比例的ＲＡＰＤｓ标记４９个．通过对４９个标记的连锁关系进行分析，其中２９个标记分布在１２个连锁群上，总图距为４８３．３ｃＭ，平均图距为２８．４２ｃＭ，２０个标记没有连锁到任何连锁群上，需要继续进行大量标记的连续分析，构建完善的高密度的遗传图谱，使之能够对数量性状位点ＱＴＬｓ进行定位，从而进行分子标记辅助选择育种（ＭＡＳ）．     

Detecting quantitative trait loci for water use efficiency in rice using a recombinant inbred line population

Breeding rice with high water use efficiency (WUE) can ameliorate water shortage through water-saving irrigation.However,WUE is a complex quantitative trait and very few studies have been conducted to measure WUE directly.In this study,a recombined inbred line population derived from a cross between an indica lowland rice and upland japonica rice was used to dissect the genetic control of WUE by fine-monitored water supply experiments.Quantitative trait loci (QTL) were scanned for 10 traits including heading date (HD),water-consumption per day (water/d),shoot weight gain per day (shootw/d),root weight gain per day (rootw/d),kernel weight gain per day (kernelw/d),average WUE at whole plant level (WUEwhole/d),average WUE for up-ground biomass (WUEup/d),average WUE for grain yield (WUEyield/d),average economic index (econindex/d),and average root/shoot ratio per day (ratio/d).The results show that most of the traits were significantly correlated to each other.Twenty-four QTL (LOD ≥ 2.0) were detected for econindex,econindex/d,WUEyield,WUEyield/d,WUEup,WUEup/d,WUEwhole,WUEwhole/d,kernelw,kernelw/d,rootw,and water/d by composite interval mapping.These QTLs are located on chromosomes 1,2,4,6,7,8,and 12.Individual QTLs accounted for 4.97%-10.78% of the phenotypic variation explained.Some of these QTLs overlapped with previously reported drought resistance QTLs detected in this population.These results provide useful information for further dissection of the genetic basis and marker-assisted selection of WUE in rice.     

Conditional and unconditional mapping of quantitative trait loci underlying plant height and tiller number in rice (Oryza sativa L.) grown at two nitrogen levels

In this study,we used 127 double haploid (DH) lines to analyze agricultural traits of rice.The DH lines,derived from a ZYQ8 (indica)/JX17 (japonica) cross by anther culture,contained 160 RFLP and 83 SSR markers.Unconditional and conditional quantitative trait loci (QTL) mapping was conducted to analyze plant height (PH) and tillers per plant (TP) at five growth stages that were grown at two nitrogen levels.Fourteen PH and 13 TP unconditional QTL were identified in the different growth stages,including 19 QTL from high-nitrogen (HN) and 14 QTL from low-nitrogen (LN) conditions.The conditional QTL for 14 genomic regions under LN/HN con-ditions showed that there was a significant effect on PH and TP across the different stages.Only one conditional QTL,ph2-3,was unable to be detected in unconditional mapping.More QTL were detected in the first four rice growth stages than in the final stage.Further-more,a line from the DH mapping population,DH78,was identified in extreme phenotypes of PH and TP that exhibited dwarfism and less-tiller (dft) characters.The gene dftl was mapped to chromosome 2 using a backcrossed population of DH78/JX17 through a map-based cloning strategy.The location of dftl coincided with the mapping region of the small-LOD peak,QTL ph2 and tp2,which were identified in plants grown in low-nitrogen conditions.Further backcrossing and fine-mapping successfully delimited the dftl locus to a 91 kb region.     

水分胁迫对水、旱稻幼苗POD活性的影响

以四种抗旱性不同的水、旱稻幼苗为材料,采用愈创木酚分光光度法测定了不同生长时期、水分胁迫以及水分胁迫处理后复水幼苗的POD活性,并与同样条件下水、早稻幼苗SOD活性变化进行比较。结果表明,不仅水、旱稻幼苗SOD活性在不同发育时期、不同水分条件发生有特定规律的变化,而且POD活性也具有类似或同步的变化,即抗旱性较强的旱稻品种在水分胁迫时POD活性上升幅度大于水稻,复水后旱稻POD活性下降的幅度也比水稻大.由于SOD和POD在生化功能上具有偶联作用以及实验结果的相似性.故可以认为,不同水分条件水、旱稻幼苗POD活性的变化和SOD一样能够反映品种间抗旱能力的差异.     

Conditional and unconditional mapping of quantitative trait loci underlying plant height and tiller number in rice (Oryza sativa L.)grown at two nitrogen levels

In this study, we used 127 double haploid (DH) lines to analyze agricultural traits of rice. The DH lines, derived from a ZYQ8 (indica)/JX17 (japonica) cross by anther culture, contained 160 RFLP and 83 SSR markers. Unconditional and conditional quantitative trait loci (QTL) mapping was conducted to analyze plant height (PH) and tillers per plant (TP) at ?ve growth stages that were grown at two nitrogen levels. Fourteen PH and 13 TP unconditional QTL were identified in the di?erent growth stages, including 19 QTL from high-nitrogen (HN) and 14 QTL from low-nitrogen (LN) conditions. The conditional QTL for 14 genomic regions under LN/HN conditions showed that there was a significant effect on PH and TP across the different stages. Only one conditional QTL, ph2-3, was unable to be detected in unconditional mapping. More QTL were detected in the ?rst four rice growth stages than in the final stage. Furthermore, a line from the DH mapping population, DH78, was identified in extreme phenotypes of PH and TP that exhibited dwarfism and less-tiller (dft) characters. The gene dft1 was mapped to chromosome 2 using a backcrossed population of DH78/JX17 through a mapbased cloning strategy. The location of dft1 coincided with the mapping region of the small-LOD peak, QTL ph2 and tp2, which were identified in plants grown in low-nitrogen conditions. Further backcrossing and fine-mapping successfully delimited the dft1 locus to a 91 kb region.     

有机-无机肥配施对板栗园土壤肥力及根系功能性状的影响

【目的】 板栗是我国大力发展的木本粮食树种,结合无机肥速效性与有机肥持久性的有机-无机肥配合施用,对培肥土壤、促进根系生长能起到重要作用。探讨有机-无机肥配施对板栗园土壤肥力及其根系功能性状的影响,以期为板栗的科学合理施肥提供依据。【方法】 以河北迁西县8 年生板栗 ‘燕山早丰’(Castanea mollissima ‘Yanshanzaofeng’)为对象,采用单因素随机区组试验设计,按质量占比设置6个处理: ①100%无机肥(C₁),②75%无机肥+25%有机肥(C_0.75O_0.25),③50%无机肥+50%有机肥(C_0.5O_0.5),④25%无机肥+75%有机肥(C_0.25O_0.75),⑤100%有机肥(O₁),⑥不施肥(CK),采用连续根钻法采集0~20、≥20~40 cm土层土样和根样,测定分析土壤理化性状及根系功能性状等指标。【结果】 ①各处理不同程度地影响土壤理化性状。O₁处理0~40 cm土层平均有机碳含量最高(5.97 g/kg),0~20 cm土层C₁处理全氮含量最大(1.33 g/kg),但以有机-无机肥配施C_0.25O_0.75处理对土壤理化性状改善具有显著促进作用(P<0.05)。 {{\mathrm{C}}_{0\mathrm{.}}}_{25} {{\mathrm{O}}_{0\mathrm{.}}}_{75}处理0~40 cm土层平均土壤C/N值较C₁和CK处理的分别提高38.81%、11.41%;与CK相比,平均碱解氮含量、有效磷含量、速效钾含量分别增加57.48%、47.49%、32.19%;土壤总孔隙度、土壤含水率分别增加11.23%、13.85%;土壤容重降低11.23%。②有机-无机肥配施显著促进0~40 cm土层中平均细根根长密度、细根表面积密度、细根体积密度、比根长(P<0.05),且0~1 mm细根增多,各处理大小总体表现为C_0.25O_0.75>C_0.5O_0.5>C_0.75O_0.25,以C_0.25O_0.75处理0~40 cm土层中平均细根生物量密度最高(511.24 g/m³),较CK处理增加35.42%,较C₁处理增加6.00%。高比例有机肥配施明显提高了细根根长、根表面积、根体积的占比。③主成分分析表明,土壤理化及根系性状指标在3个主成分上均有较高的荷载值,不同处理下土壤肥力与根系指标优劣综合排序为C_0.25O_0.75>C_0.5O_0.5>C_0.75O_0.25>O₁>C₁>CK。【结论】 有机-无机肥配施中的C_0.25O_0.75处理有效提高了土壤C/N、速效养分含量,0~1 mm细根增多,提高吸收根比例,是河北迁西县板栗园的较佳施肥模式。     

Ethylene signaling in rice

Ethylene regulates many aspects of growth, development and responses to environmental stresses in plants. Its signaling pathway has been established in model dicotyledonous plant Arabidopsis. However, its roles and signal transduction in monocotyledous rice plant remain largely unknown. In this review, we summarize the current advances in rice ethylene signaling studies and compare these with the results from Arabidopsis and other plants. Most of the components homologous to those in Arabidopsis ethylene signaling pathway have been found in rice, including five ethylene receptors, OsEIN2, OsEIL1, and OsERFs. Rice ethylene receptors are functionally more divergent than that of Arabidopsis. OsEIN2 and OsEIL1 display limited roles in regulation of rice ethylene responses compared with their Arabidopsis orthologs. ERF-like proteins OsERF1 and OsEBP-89 appear to be involved in rice ethylene signaling. However, whether they are activated through OsEIN2 and OsEIL1-mediated pathway needs further studies. Given that rice uses ethylene to control many processes that do not exist in Arabidopsis, it seems that new components or new mechanisms may exist in rice ethylene signaling pathway.