Identification of QTL for kernel number-related traits in a rice chromosome segment substitution line and fine mapping of qSP1

A chromosome segment substitution line (CSSL) is a powerful tool for combining quantitative trait locus (QTL) mapping with the pyramiding of desirable alleles. The rice CSSL Z1364 with increased kernel number was identified in a BC3F8 population derived from a cross of Nipponbare as the recipient with Xihui 18 as the donor parent. Z1364 carried three substitution segments distributed on chromosomes 1, 6, and 8. The mean substitution length was 1.19 Mb. Of 17 QTL identified on the substitution segments, qSP1 for spikelets per panicle, qSSD1 for seed-set density, and qNSB1 for number of secondary branches explained respectively 57.34%, 87.7%, and 49.44% of the corresponding phenotypic variance and were all linked to RM6777. Chi-square analysis showed that the increased kernel number in Z1364 was inherited recessively by a single gene. By fine mapping, qSP1 was delimited to a 50-kb region on the short arm of chromosome 1. Based on DNA sequence, a previously uncharacterized rice homolog of Arabidopsis thaliana AT4G32551 was identified as a candidate gene for qSP1 in which mutation increases the number of spikelets and kernels in Z1364. qSP1 was expressed in all tissues, but particularly in 1-cm panicles. The expression levels of OsMADS22, GN1A, and DST were upregulated and those of LAX2, GNP1, and GHD7 were downregulated in Nipponbare. These results provide a foundation for functional research on qSP1.

Mapping of QTLs Related to Grain Weight Using Chromosome Single Segment Substitution Lines in Rice

Grain weight, one of the major factors determining rice yield, is a typical quantitative trait control ed by multiple genes. With Guangluai 4 as recipient and Nipponbare as donor, a population of 119 chromosome single segment substitution lines had been developed. Correlation analysis between grain weight and grain shape by SPSS revealed that 1 000-grain weight shared extremely significant posi-tive correlation with grain length and length-width ratio, but no significant correlation with grain width and thickness. The QTL analysis of grain weight was carried out using one-way analysis of variance and Dunnett＇s test. Nineteen stable QTLs re-sponsible for grain weight were identified over two years. Al 19 QTLs were identi-fied on al chromosomes except for chromosome 10 and 12 at a significance level of P≤0.001. Among them, 10 QTLs had a positive effect and were derived from the Nipponbare al ele, the additive effect of these QTLs ranged from 0.49 to 2.74 g, and the contributions of the additive effects ranged from 2.00% to 11.05%. Another 9 QTLs had a negative effect and were al derived from Guangluai 4 al ele, the ad-ditive effect of these QTLs ranged from 0.60 to 2.35 g, and the contributions of the additive effects ranged from 2.40% to 9.84%. The results provide a basis for the fine mapping and gene cloning of novel locus associated with rice grain weight.

Mapping QTLs Associated with Sheath Blight Resistance Using Chromosome Segment Substitution Lines of Rice(Oryza sativa L.)

In this study, a population of 119 chromosome segment substitution lines （CSSLs） derived from backcross between indica 9311 and japonica Nipponbare was employed to map quantitative trait loci （QTL） associated with sheath blight resis-tance in rice with toothpick inoculation method. A total of three sheath blight resis-tance-associated QTLs （qsb8-1, qsb8-2 and qsb8-3） were identified, which were lo-cated on adjacent molecular markers RM3262, RM5485 and RM3496 of chromo-some 8; the genetic interval was 81.7cM-91.7cM, 91.7cM-108.1cM and 108.1cM-119.6cM, respectively. The additive effect of qsb8-2 was negative, indicating that sheath blight resistance of susceptible parent harboring qsb8-2 fragment was en-hanced; additive effects of qsb8-1 and qsb8-3 were positive, indicating that sheath blight resistance of susceptible parent harboring qsb8-1 and qsb8-3 fragments was reduced.

Unconditional and Conditional QTL Mapping for Tiller Numbers at Various Stages with Single Segment Substitution Lines in Rice(Oryza sativa L.)

Tiller is one of the most important agronomic traits which influences quantity and quality of effective panicles and finally influences yield in rice. It is important to understand ＂static＂ and ＂dynamic＂ information of the QTLs for tillers in rice. This work was the first time to simultaneously map unconditional and conditional QTLs for tiller numbers at various stages by using single segment substitution lines in rice. Fourteen QTLs for tiller number, distributing on the corresponding substitution segments of chromosomes 1, 2, 3, 4, 6, 7 and 8 were detected. Both the number and the effect of the QTLs for tiller number were various at different stages, from 6 to 9 in the number and from 1.49 to 3.49 in the effect, respectively. Tiller number QTLs expressed in a time order, mainly detected at three stages of 0-7 d, 14-21 d and 35-42 d after transplanting with 6 positive, 9 random and 6 negative expressing QTLs, respectively. Each of the QTLs expressed one time at least during the whole duration of rice. The tiller number at a specific stage was determined by sum of QTL effects estimated by the unconditional method, while the increasing or decreasing number in a given time interval was controlled by the total of QTL effects estimated by the conditional method. These results demonstrated that it is highly effective and accurate for mapping of the QTLs by using single segment substitution lines and the conditional analysis methodology.

A Preliminary Study of Mapping Genes Underlying Complex Traits Based on Chromosome Segment Substitution Lines

Complex traits are the features whose properties are determined by multiple factors, which can be genetic or environmental. Most of economically important characteristics of plants and animals belong to this special catego-

QTLs Mapping for Salinity Tolerance at Seedling Stage or Rice(Oryza sativa L.) Using Chromosome Segment Substitution Lines

In this study, a population of chromosome segment substitution lines （CSSLs） derived from the cross between 9311 （indica） and Nipponbare （japonica） was employed to map the quantitative trait loci （QTLs） for salt tolerance under the salt stress simulated with 0.5% NaCI, using survival rate as the index. The data were analyzed by QTL IciMapping v3.1, and the results showed that one QTL （QSsr3） related to salt tolerance was located in the vicinity of the marker RM1350 on chromosome 3, into a genetic interval of 113.2-132.8 cM, with a contribution rate of 17.75%. The additive effect was 10.9, indicating that the QTL derived from the parent Nipponbare improved the salt tolerance of rice at seedling stage. This study will provide a theoretical basis for the selection of salt tolerant rice germplasm.

Detection of QTL for Cold Tolerance at Bud Bursting Stage Using Chromosome Segment Substitution Lines in Rice (Oryza sativa)

Ab The cold tolerance at the bud bursting stage （CTB） was evaluated at 5℃ by using a set of 95 chromosome segment substitution lines （CSSLs） derived from an indica rice 9311 and a japonica rice Nipponbare with a genetic background of 9311. The result showed that six CSSLs had slightly stronger effect on CTB than 9311. Total four quantitative trait loci （QTLs） for CTB were preliminary mapped on chromosomes 5 and 7 by substitution mapping, qCTB-5-1, qCTB-5-2 and qCTB-5-3 were mapped in the region of RM267-RM1237, RM2422-RM6054 and RM3321-RM1054, which were 21.3 cM, 27.4 cM and 12.7 cM in genetic distance on rice chromosome 5, respectively, qCTB-7 was mapped in a 6.8-cM region of RM11-RM2752 on rice chromosome 7.

QTL Mapping for Rice RVA Properties Using High-Throughput Re-sequenced Chromosome Segment Substitution Lines

The rapid visco analyser （RVA） profile is an important factor for evaluation of the cooking and eating quality of rice. To improve rice quality, the identification of new quantitative trait loci （QTLs） for RVA profiling is of great significance. We used a japonica rice cultivar Nipponbare as the recipient and indica rice 9311 as the donor to develop a population containing 38 chromosome segment substitution lines （CSSLs） genotyped by a high-throughput re-sequencing strategy. In this study, the population and the parent lines, which contained similar apparent amylose contents, were used to map the QTLs of RVA properties including peak paste viscosity （PKV）, hot paste viscosity （HPV）, cool paste viscosity （CPV）, breakdown viscosity （BKV）, setback viscosity （SBV）, consistency viscosity （CSV）, peak time （PET） and pasting temperature （PAT）. QTL analysis was carried out using one-way analysis of variance and Dunnett＇s test, and stable QTLs were identified over two years and under two environments. We identified 10 stable QTLs： qPKV2-1, qSBV2-1; qPKV5-1, qHPV5-1, qCPV5-1; qPKV7-1, qHPV7-1, qCPV7-1, qSBV7-1; and qPKV8-1 on chromosomes 2, 5, 7 and 8, respectively, with contributions ranging from -95.6% to 47.1%. Besides, there was pleiotropy in the QTLs on chromosomes 2, 5 and 7.

Genetic Dissection, Marker-assisted Introgression, and Pyramiding of Agronomic Traits in Rice

Through the efforts of the International Rice Genome Sequencing Project, the whole genome sequence of rice has been decoded (International Rice Genome Sequencing Project, 2005). This sequence information has

Mapping of Hd-6-2 for Heading Date Using Two Secondary Segregation Populations in Rice

Heading date is one of the most important traits for rice adaption to different cultivation areas and crop seasons. In this study, two single segment substitution lines(SSSLs), W31-41-61-3-11-3-6-7(W31-SSSL) and W32-59-80-2-11-1-10(W32-SSSL) with substituted intervals derived from the donor parents IR66897 B(W31) and IR66167-27-5-1-6(W32), respectively, with Huajingxian 74(HTX74) were found to comprise a gene for extremely late-heading date, and the gene was tentatively designated as Hd-6-2. Two secondary F2 segregating populations were developed by crossing the two heterozygous SSSLs with HJX74 to map Hd-6-2 gene. According to phenotype analysis of the two mapping populations, the late heading date trait was controlled by a major recessive gene. In the segregation population derived from W31-SSSL, Hd-6-2 was mapped on chromosome 6 between PSM677 and RM204 with the genetic distances of 1.3 and 2.7 c M, respectively. In the population of W32-SSSL, the gene for heading date was mapped to the similar region as Hd-6-2 and co-segregated with PSM672. The sequence alignment of Hd3 a in the coding domains and promoter regions of HJX74 and W31-SSSL are completely consistent, whereas there was a great difference between W32-SSSL and HJX74, suggesting that Hd3 a could hardly be the main cause of the heading date variation in W31-SSSL, but it was probably the main reason for the change of heading stage in W32-SSSL.

激光雷达点云特征线检测与结构化研究进展与展望

实景三维(3D)建设是国家新型基础测绘建设的重要组成部分,是对在3D地理场景上承载结构化、语义化、支持人机兼容理解和物联实时感知的地理实体进行构建。而结构化是实现地理实体单体分割并获取其几何轮廓及组成结构的过程。随着大范围、城市级激光点云数据采集成本逐渐降低,3D点云的应用也越来越广泛。基于3D点云能完成生成地物的结构化表达,涉及线、面、体重建及语义分割、实例分割等。点云数据处理的核心内容是点云特征线检测、特征线线段化及特征线结构化。因此,点云特征线对点云处理和行业应用具有理论和实践价值。进行城市场景点云自适应特征线检测和精细结构化研究具有重要意义;研究点云特征线智能感知理论及结构化表达方法能为点云数据处理提供新的视角,对各类工程实践具有重要的理论指导意义,可服务于实景3D建设、二维(2D)、3D高清地图生成等具体应用。本文从点云特征线检测、点云特征线线段化、点云特征线结构化角度进行国内外研究现状综述,总结归纳点云特征线检测与结构化研究存在问题,并明确下一步研究思路。

展颖野生稻株高性状的遗传与SD1基因的等位变异分析

为了探究SSSL-B50和华粳籼74(HJX74)株高差异的原因,利用SSSL-B50与HJX74回交构建F2群体进行株高性状遗传分析与基因定位。结果显示,F1植株表现为高秆;260个单株组成的F2群体株高出现分离,高秆植株与半矮秆植株分离比例符合3∶1(χ^(2)=0.18<3.84),说明SSSL-B50高秆性状为显性性状,受1对显性等位基因控制。利用IciMapping软件对F2进行连锁分析,将SSSL-B50携带的高秆基因定位在1号染色体代换片段上的标记S18和X161之间38.38~39.07 Mb。候选基因筛选分析发现,定位区间内存在着“绿色革命”基因座位SD1。对展颖野生稻、SSSL-B50及HJX74进行SD1基因测序及序列比对,发现HJX74的CDS序列与展颖野生稻、SSSL-B50相比有280 bp的缺失,导致氨基酸编码提前终止。qRT-PCR结果表明,SD1表达量在SSSL-B50茎秆的第2,3,4节均显著高于HJX74。此外,与前人报道结果相比,展颖野生稻SD1基因编码的氨基酸序列发生了2处改变(E100G、Q339R)。研究结果弄清楚了展颖野生稻单片段代换系SSSL-B50高秆性状受SD1调控,同时从展颖野生稻鉴定到了SD1的新等位型SD1Glu。

基于点线特征的快速视觉惯性SLAM算法

为了提高基于点特征的SLAM算法的定位精度和鲁棒性,提出一种点线特征融合的快速单目视觉惯性SLAM算法。使用ELSED算法快速提取高质量的线特征,在非关键帧追踪时,基于连续帧之间微小运动的假设,实现连续图片间的快速线段匹配,且无需线段描述子。在插入新关键帧时,提取线段描述子来完成关键帧之间的线特征匹配,创造新的地图线。最后在公开数据集上进行实验,结果表明:ELSED算法在提取高质量线段的同时,耗时仅为LSD算法的13%;与传统利用线段描述子的匹配算法相比,此算法的时间效率提升了83%,并减少线段误匹配,提高系统定位精度,系统的平均跟踪帧率为33帧/s,保证了系统的实时性。

一种高精度地图辅助的UWB/INS组合定位方法

提出了一种高精度地图辅助的UWB/惯性导航系统(Inertial Navigation System,INS)紧组合定位算法,即利用数字测图方法获得高精度地图信息并建立地图数据库,采用线段匹配算法识别非视距(Non-Line-of-Sight,NLOS),使用抗差卡尔曼滤波(Robust Kalman Filter,RKF)融合UWB/INS的组合定位方法。实验结果表明,本文提出的算法平面定位精度在0.25 m内,能够在复杂的室内环境下提高UWB/INS组合定位系统的定位精度和稳定性。

移动机器人激光SLAM导航定位方法研究

为了提高激光SLAM导航定位的实时性和稳定性,采用自适应阈值法、迭代适应点以及最小二乘法结合直线度的方法提取局部地图中的特征线段和全局地图中的线段,通过特征线段匹配进行初始定位。利用惯性导航位姿推算结合地图匹配的方法进行动态定位,获得机器人的实时位姿。同时,采用动态重定位的方法进行重定位,提高了移动机器人对工作环境的适应能力和可靠性。实验表明,基于地图匹配的导航定位算法的定位精度在±40mm以内,定位的时间不大于0.03s,可以较好地满足机器人的实际导航需求。

水稻粒型染色体片段代换系Z8的QTL定位与次级代换系选育

粒型是水稻重要的农艺性状,由多个基因调控,属于典型的数量性状,与产量密切相关.染色体片段代换系(Chromosomal Segment Substitution Line,CSSL)是研究数量性状的良好材料,能够将复杂的数量性状转化成单个的遗传因子,从而有效分离主效数量性状基因座(Quantitative trait locus,QTL)或关键基因,并准确估算其遗传效应.以粳稻日本晴(Nipponbare)为受体,优良恢复系R225为供体构建的CSSL群体中鉴定到1个水稻长宽粒代换系Z8,其携带14个来自供体亲本R225的染色体片段,平均代换长度8.41 Mb.与受体亲本日本晴相比,Z8的粒长、粒宽、长宽比、株高、一次枝梗数、二次枝梗数、千粒质量、着粒密度和每穗总粒数等性状均增加(p<0.01或p<0.05),有效穗数、穗长和结实率均降低(p<0.01),而每穗实粒数和单株产量的差异无统计学意义.扫描电镜检测表明,Z8籽粒外颖壳表皮细胞长度、宽度分别增加了33.14μm和5.20μm(p<0.01),而单位面积细胞数目则减少了3.4个(p<0.01),表明Z8籽粒变宽、变长可能是由于籽粒外颖壳细胞纵向和横向增大所致.利用日本晴/Z8构建的次级F2分离群体对粒长、粒宽等10个农艺性状进行QTL定位,共鉴定到33个QTLs,其中粒长、粒宽和长宽比各6个,千粒质量4个,株高和穗长各3个,每穗实粒数2个,一次枝梗数、二次枝梗数与结实率各1个,贡献率在2.04%~88.67%之间.结合QTL定位与分子标记辅助选择(MAS),从F3家系中鉴定到2个含目标性状QTL的双片段代换系,4个三片段代换系,3个四片段代换系,14个五片段及以上代换系.目标性状的QTL定位以及次级代换片段的成功选育,为进一步研究目标性状的遗传机理提供了良好的理论参考和材料支撑.

利用东乡野生稻染色体片段置换系鉴定穗部性状主效QTL

【目的】稻穗是水稻产量的主要承载者,发掘穗部性状相关的主效QTL对进一步精细定位、克隆和育种利用具有重要意义。【方法】以粳稻日本晴为受体、东乡野生稻为供体构建的一套染色体片段置换系(chromosome segment substitution lines,CSSLs)群体为材料,在4个生态环境下进行穗部性状表型鉴定与主效QTL定位分析。【结果】不同生态环境下CSSL群体穗部性状存在较大幅度变异,东乡野生稻染色体片段的导入显著改变背景亲本的穗部性状,具有明显的增产效应;早季、中季、晚季和海南环境下共检测到64个控制每穗颖花数和籽粒大小的QTL,其中qPL2、qSN1.2、qSN2、qFGN3、qTGW2、qTGW12.1和qSL2在3个环境下稳定表达,21个QTL在2个环境下被重复检测到,其余QTL仅在单一环境下被发现;主效QTLqSN1.1、qSN1.2、qSN2、qSN3和qSN12对每穗颖花数具有明显的影响,多个QTL聚合具有明显调控每穗颖花数的功能;主效QTLqSL2、qSL3.2、qSLW3.1、qSLW3.2、qTGW8.1和qSLW10对籽粒大小具有明显的影响。这些位点分别作用于粒长、粒宽和长宽比,相互作用、共同决定籽粒大小;同时,穗部性状QTL成簇分布于10个染色体区段,其中主效QTL簇qGNS1.1、qGNS1.3、qGNS2.1、qGNS3.1、qGNS9、qGNS10和qGNS12包含多个调控每穗颖花数及籽粒大小性状的QTL,可在不同环境下稳定表达。来自东乡野生稻的等位基因具有明显调控产量表型的功能。【结论】研究结果不仅为东乡野生稻优异基因发掘奠定基础,也可为水稻穗部性状的分子育种提供新基因源。

基于单片段代换系的水稻苗高QTL定位和上位性效应分析

【目的】挖掘控制水稻苗高的稳定QTL,并分析其上位性效应,为水稻苗高的分子育种提供QTL和理论参考。【方法】以IR65598-112-2为供体、优良品种‘华粳籼74’为受体的单片段代换系(Single segment substitution line,SSSL)为材料,通过测定SSSL与‘华粳籼74’的苗高差异,对苗高QTL进行定位;通过代换作图缩小QTL的区间,并分析2个苗高QTL的上位性效应。【结果】在第3号染色体长臂端定位到2个相邻的苗高QTLs(qSH3-1和qSH3-2),分别位于第3号染色体的32.59—33.08 Mb和33.16—34.81 Mb区间,长度分别为0.49和1.65 Mb;加性效应分别为-0.86和-1.09 cm;加性效应表型贡献值分别为-4.14%和-5.15%;包含这2个QTL的SSSL的苗高与‘华粳籼74’无显著差异。【结论】本研究定位到2个苗高QTL,这2个QTL之间可能存在显著的上位性。

语义线特征辅助的动态SLAM

动态环境干扰是视觉同时定位与地图构建(SLAM)领域内一个亟待解决的问题,场景中的运动对象会严重影响系统定位精度。结合语义信息和几何约束更强的线特征辅助基于传统ORB特征的SLAM系统来解决动态SLAM问题。首先采用深度学习领域的优秀成果SOLOv2作为场景分割网络,并赋予线特征语义信息;完成物体跟踪和静态区域初始化后,使用mask金字塔提取并分类特征点;再使用极线约束完成动态物体上点线特征的剔除;最后融合静态点线特征完成位姿的精确估计。在TUM动态数据集上的实验表明,所提出的系统比ORB-SLAM3的位姿估计精度提高了72.20%,比DynaSLAM提高了20.42%,即使与近年来同领域内的优秀成果相比也有较好的精度表现。

Tectonic boundaries in the South China Sea from aeromagnetic signature

Magnetic data has been widely applied in the tectonic division.High-resolution magnetic data were used to analyze the geotectonic zoning of the South China Sea.Based on the newly compilated magnetic data,the processing results and the distribution of known faults,we consider that the U-shaped line approximately along the South China Sea national boundary of China shown in the magnetic map is a significant geological and geophysical boundary.We first described the linear characteristics of the magnetic data and then applied pseudo-gravity,Euler deconvolution,tilt derivatives,and the texture segmentation method to process the data.Results show that the dividing line between the South China Sea and the surrounding blocks is approximately along this U-shaped line.The dividing line between the South China domain and the South China Sea domain is along with the Dongsha Islands to Xisha Trough,which is different from the previous geophysical zoning results.Our results are almost consistent with those of the gravity data indicating roughly the tectonic zonation along the U-shaped line.