基于不完全双列杂交设计的水稻农艺性状配合力基因组预测

【目的】在亲本一般配合力的基础上优选特殊配合力高的杂交种，是水稻杂种育种的关键。基因组选择基于覆盖全基因组的分子标记和样本的表型数据建立预测模型，实现对品种更加可靠的选择。【方法】本研究利用一组基于不完全双列杂交(NCII设计)的水稻数据集，考查其多个农艺性状配合力的基因组预测能力。并比较了不同训练群体构建方法对杂交种表型预测能力的影响。【结果】8个农艺性状一般配合力的预测能力由其遗传率主导，从0.3888到0.7367。杂交种特殊配合力的预测能力较低，但是直接预测杂交种的表型可以获得较高的预测能力。【结论】基因组预测水稻亲本一般配合力是有效的，能够帮助育种家实现对亲本的科学选择。如果要选配杂交种，直接预测杂交种表型是最有效的手段。此时让更多的亲本均衡地参与杂交种训练集的组配，有利于获得更高的预测能力。     

基于不完全双列杂交设计的水稻农艺性状配合力基因组预测

[目的]在亲本一般配合力的基础上优选特殊配合力高的杂交种,是水稻杂种育种的关键。基因组选择基于覆盖全基因组的分子标记和样本的表型数据建立预测模型,实现对品种更加可靠的选择。[方法]本研究利用一组基于不完全双列杂交(NCII 设计)的水稻数据集,考查其多个农艺性状配合力的基因组预测能力。并比较了不同训练群体构建方法对杂交种表型预测能力的影响。[结果]8个农艺性状一般配合力的预测能力由其遗传率主导,从0.3888 到0.7367。杂交种特殊配合力的预测能力较低,但是直接预测杂交种的表型可以获得较高的预测能力。[结论]基因组预测水稻亲本一般配合力是有效的,能够帮助育种家实现对亲本的科学选择。如果要选配杂交种,直接预测杂交种表型是最有效的手段。此时让更多的亲本均衡地参与杂交种训练集的组配,有利于获得更高的预测能力。     

水稻灌浆期耐热害的数量性状基因位点分析

 利用由98个家系组成的Nipponbare / Kasalath // Nipponbare回交重组自交系群体及其分子连锁图谱，以粒重感热指数\[（适温粒重-高温粒重）/适温粒重×100\]为评价指标，采用混合线性模型的QTL定位方法，对水稻灌浆期耐热性的主效、上位性数量性状基因位点及其与环境的互作进行分析。共检测到3个灌浆期耐热性主效QTL，分别位于第1、4和7染色体上，LOD值为8.16、11.08和12.86，贡献率8.94%、17.25%和13.50%。其中位于第4染色体标记C1100-R1783之间的QTL，没有显著的上位性和环境互作效应，表明在不同环境和遗传背景中的表达较为稳定，在水稻耐热性育种中可能具有较大的利用价值，其耐热性等位基因来自亲本Kasalath，高温热害时可减少粒重损失3.31%。位于第1染色体标记R1613-C970之间的QTL和第7染色体标记C1226-R1440之间的QTL，耐热性等位基因来自亲本Nipponbare，分别可减少粒重损失2.38%和2.92%。这两个QTL均具有与环境的互作效应，其中第7染色体上的QTL还和其他基因位点有互作。检测到8对加性×加性上位性互作QTL，分布于第1、2、3、5、7、8、10和12染色体上。没有检测到上位性QTL与环境的互作效应。     

Arsenic Stress Responses and Tolerance in Rice: Physiological,Cellular and Molecular Approaches

Arsenic (As), a potentially toxic metalloid released in the soil environment as a result of natural as well as anthropogenic processes, is subsequently taken up by crop plants. In rice grains, As has been reported in Asia, North America and Europe, suggesting a future threat to food security and crop production. As³⁺ by dint of its availability, mobility and phytotoxicity, is the most harmful species of As for the rice crop. Specific transporters mediate the transport of different species of As from roots to the aboveground parts of the plant body. Accumulation of As leads to toxic reactions in plants, affecting its growth and productivity. Increase in As uptake leads to oxidative stress and production of antioxidants to counteract this stress. Cultivars tolerant to As stress are efficient in antioxidant metabolism compared to sensitive ones. Iron and selenium are found to have ameliorating effect on the oxidative stress caused by As. Microbes, even many indigenous ones, in the plant rhizosphere are also capable of utilizing As in their metabolism, both independently and in association. Some of these microbes impart tolerance to As-stress in plants grown in As contaminated sites.     

杂交水稻稳产性配合力初步研究

 采用多点的不完全双列杂交设计,在AMMI模型分析稳定性的基础上,进一步分析了稳产性的配合力及其与丰产性的关系,结果表明杂交稻丰产性及其亲本的配合力均与试点存在交互作用,材料间稳定性差异较大;稳产性与丰产性间相关不显著;杂交稻F1的稳产性同时受双亲一般配合力和特殊配合力的作用,且以基因加性效应为主,但均不可忽视。选育稳产性好的杂交稻组合,至少应有一个稳产性配合力高的亲本。     

利用分子标记进行水稻苗期耐冷性相关性状的QTLs研究

用二九青和Yukihikari杂交后再经8代自交得到的79个重组自交系(RIL)群体为材料,构建了包含89个微卫星标记的分子连锁图谱.以低温下缺绿、枯萎死苗为指标对水稻苗期耐冷性数量性状位点(QTLs)进行了定位.在17℃,18℃和15～20℃ 3种不同低温处理情况下,以叶绿素含量为指标,共定位了11个QTLs,它们分别位于染色体1(2个),2(2个),3,5,6,7,8,9,12上;其中3个QTLs在3种环境中都能检测到,1个QTL在2种环境中检测到,而其余7个QTLs只能在1种环境中检测到;11个QTLs各自引起的表型变异为5.68%～27.42%.以枯萎死苗作为指标共定位了5个QTLs,分别位于染色体3,4,7,8,11上,各QTL控制的表型变异范围为7.65%～49.34%;其中位于染色体11上的RM224位点引起的表型变异达49.34%,是一个主效QTL.缺绿和枯萎死苗都是不耐冷品种受低温影响的表现,但从分子图谱定位的结果看,它们是由不同的基因位点控制的,没有连锁遗传关系.由此推断,水稻苗期耐冷性是一个由多基因控制的复杂遗传现象.     

应用分子标记检测水稻耐盐性的QTL

 利用特三矮2号/CB组合构建了重组自交系群体(RI)。以60个RFLP标记检测142个纯系的基因型。在含有NaCl的电导率为12 dS/m的培养液中鉴定这些纯系的耐盐性。结果表明,RI群体的耐盐性出现超亲分离。构建了一张覆盖11条染色体、含52个标记位点的连锁图。仅检测到一个位于第5染色体的位点(RG13)显著与耐盐性有连锁。该位点的表型贡献率为11.6%。来自母本的该位点可提高耐盐性。分别对RG13与其它59个标记位点间的互作做检测,仅发现3对互作显著,即RG13×RG104; RG13×RG143; RG13×RG716。当来自母本的RG13分别与来自父本的RG104和RG143重组时,均明显提高耐盐性。分别来自母本的RG13和RG716能产生提高耐盐性的互作。这些基因互作结果为超亲分离提供了理论依据。     

水稻耐冷性遗传及基因定位研究概况与展望

综述了水稻低温发芽力,幼苗期、孕穗期和开花期耐冷性等遗传研究概况和近年来在水稻耐冷性数量性状基因定位(QTLs)研究方面所取得的进展,并展望了今后的水稻耐冷性研究方向。     

水稻耐热性的QTL定位及耐热性与光合速率的相关性

应用典型的籼粳交组合IR64×Azucena花药培养的DH群体及其已构建的分子连锁图谱,在田间及温室高温条件下对该DH群体的结实性状进行考查,采用QTLmapper 1.0软件检测控制结实率的加性和上位性效应的QTL。在第1、3、4、8和11等5条染色体上,共检测到6个具有加性效应的QTL,其中位于第1、3染色体的2个加性效应QTL来自父本Azucena的等位基因,它们是耐热的QTL,能分别提高结实率9.50和6.46个百分点,其贡献率分别为19.15%和2.86%;位于其余3条染色体的4个加性效应的QTL来自母本IR64的等位基因,它能提高结实率4.33~10.37个百分点,在第1、2、3、4、5、7、8、11等8条染色体之间还检测到8对加性×加性上位性效应,其贡献率为2.27%~8.13%。同时还对水稻分蘖盛期和抽穗期进行了光合速率的测定,发现抽穗期剑叶光合速率与耐热性呈显著的正相关。     

利用贝叶斯法进行水稻籽粒植酸含量性状的QTL定位及互作分析

 利用水稻植酸含量差异较大的品种中花11(粳型)和LPA（籼型）为亲本杂交获得F2群体的172个单株,构建了含126个SSR和4个STS标记的遗传连锁图谱,利用贝叶斯（Bayesian）法对水稻籽粒植酸含量性状进行了主效应QTL定位和上位性互作分析。共检测到 3 个与水稻籽粒植酸含量性状有关的主效QTL,分布在第3、5和6 染色体的相应区间内,表型贡献率分别为538%、802%和462%,降低籽粒植酸含量的等位基因均来自亲本LPA。检测到10对上位性互作影响籽粒植酸含量, 分布于水稻第1、3、5、6、11染色体上,互作效应值为169～518,其表型变异的解释率为867%～2473%。     

Inheritance and QTL Mapping of Salt Tolerance in Rice

An F2 population derived from the cross between Jiucaiqing (japonica) and IR36 (indica) was used to analyze the inheritance of salt tolerance in rice by genetic model of major-genes plus polygenes, and to map the corresponding QTLs by SSR molecular markers. Rice plants of P1, P2, F1 and F2 at 5- to 6- leaf stage were treated under 140 mmol/L NaCI for 10 days. Three indices representing the ability of salt tolerance of rice seedlings were measured, including salt tolerance rating (STR), Na^ /K^ ratio in roots and dry matter weight of shoots (DWS). STR, Na^ /K^ and DWS were all controlled by two major genes with modification by polygenes. Heritability of these traits from major genes was 17.8, 53.3 and 52.3%, respectively. The linkage map constructed by 62 SSR molecular markers covered a total length of about 1 142 cM. There were three QTLs detected for STR located on chromosome 1, 5 and 9, two QTLs for DWS on chromosomes 8 and 9, and two QTLs for Na^ /K^ on chromosomes 2 and 6, one on each chromosome respectively. Single QTL accounted for 6.7 to 19.3% of phenotypic variation. Identification method of salt tolerance in rice and breeding of rice varieties with salt tolerance based on molecular markers assisted selection had been discussed.     

Effects of Water Management,Arsenic and Phosphorus Levels on Rice Yield in High-Arsenic Soil-Water System

Aerobic rice （Oryza sativa L.） cultivation is considered an alternative production system to combat increased water scarcity and arsenic （As） contamination in the food chain. Pot experiments were conducted at the Wheat Research Centre, Dinajpur, Bangladesh to examine the role of water management （WM）, As and phosphorus （P） on yield and yield attributes of boro （variety BRRI dhan 29） and aman （variety BRRI dhan 32） rice. A total of 18 treatment combinations of the three levels of As （0, 20 and 40 mg/kg） and P （0, 12.5 and 25.0 mg/kg） and two WM strategies （aerobic and anaerobic） were investigated. Yield attributes were significantly affected by increasing As levels. Grain yields of BRRI dhan 29 and BRRI dhan 32 were reduced from 63.0 to 7.7 and 35.0 to 16.5 g/pot with increasing As application, respectively, indicating a greater sensitivity of BRRI dhan 29 than BRRI dhan 32. Moreover, As toxicity was reduced with aerobic compared to anaerobic WM for all P levels. During early growth stages, phytotoxic symptoms appeared on BRRI dhan 29 and BRRI dhan 32 rice stems with increasing As levels without applying P under anaerobic WM. Under anaerobic and As-contaminated conditions, BRRI dhan 29 was highly susceptible to straighthead, which dramatically reduced grain yields. There were significant relationships between the number of effective tillers per pot and root dry weight, grain yield, and number of fertile and unfertile grains per pot for both BRRI dhan 29 and BRRI dhan 32 （P＆lt;0.001）. Our findings indicate that rice could be grown aerobically in As-contaminated areas with a reduced risk of As toxicity and yield loss.     

水稻耐盐性数量性状位点的初步检测

用RFLP分析技术和分蘖株系法对由耐盐性品种Pokkali和盐敏感品种Peta配制的BC1(Peta/Pokkali∥Peta)群体分别检测水稻苗期和成熟期耐盐性数量性状位点(QTLs)。表型鉴定在含(处理)或不含(对照)60 mol/m3 NaCl的营养液中进行,苗期观测盐害级别、苗Na+含量和鲜重/干重比值3项指标,成熟期测定10种农艺性状处理与对照的相对值。从水稻12条染色体上筛选出43个多态性标记,对上述指标分别作点分析,共检出15个连锁标记。连锁标记的分布特点显示,在研究所涉及的基因组范围内存在4个影响苗期耐盐性的QTL,其增效等位基因均来自耐盐品种Pokkali;影响成熟期耐盐性的QTL分布于7条染色体的1或2个连锁区间上,其有利基因来自双亲;RG678和RZ400B~RZ792附近的2个QTL在全生育期都能表达较强耐盐性。     

水稻耐光氧化特性的QTL定位

利用由127个株系组成的来源于籼稻品种窄叶青8号和粳稻品种京系17的加倍单倍体群体,以耐性指数和敏感性指数为指标,采用QTL Mapper 1.6统计软件进行水稻耐光氧化反应特性的QTL定位和上位性分析,共检测到控制耐性指数的1个加性效应QTL,位于第3染色体上;控制敏感性指数的加性效应QTL 5个,分别位于第1、1、6、8和9染色体上。还检测到3对影响耐性指数的加性×加性上位性互作效应QTL和5对敏感性指数的上位性QTL。还对41个水稻材料进行了光氧化实验筛选。     

Identification of QTLs for Cadmium Tolerance During Seedling Stage and Validation of qCDSL1 in Rice

Cadmium(Cd)is a non-essential toxic metal that is harmful to plants.To investigate the genetic mechanism of Cd tolerance in rice,quantitative trait loci(QTLs)associated with Cd tolerance at the seedling stage were analyzed using a recombinant inbred line(RIL)population derived from a cross between PA64s and 93-11.A total of 36 QTLs associated with shoot length,root length,shoot dry weight,root dry weight and total dry weight were detected in Hangzhou and Lingshui of China.Among them,15 QTLs were identified under the control condition and 15 QTLs were identified under the Cd stress condition,and 6 QTLs for Cd tolerant coefficient were detected on chromosomes 1,3,7 and 9.The qCDSL1.1 and qCDSL1.2 were identified in Hangzhou and Lingshui,respectively,and had overlapping intervals on chromosome 1.To further confirm the effects of qCDSL1.1 and qCDSL1.2,we developed a chromosome segment substitution line(CSSL),CSSLqCDSL1,in 93-11 background harboring qCDSL1.1/qCDSL1.2 from PA64s.Compared to 93-11,CSSLqCDSL1 had increased shoot length under the Cd stress condition.These results pave the way for further isolation of those genes controlling Cd tolerance in rice and marker-assistant selection of rice elite varieties with Cd tolerance.     

Mapping of QTLs for Leaf Malondialdehyde Content Associated with Stress Tolerance in Rice

Malondialdehyde (MDA) is the final product of lipid peroxidation, and MDA content can reflect the stress tolerance of plants. To map QTLs conditioning the MDA content in rice leaves, a recombinant inbred line (RIL) population with 247 lines derived from an indica-indica cross Zhenshan 97B×Milyang 46, and a linkage map consisting of 207 DNA markers were used. The RIL population showed a transgressive segregation in the MDA content of rice leaves. Two QTLs for the MDA content in rice leaves were detected in t...     

Flooding Tolerance in Rice: Focus on Mechanisms and Approaches

Flooding is one of the most hazardous natural disasters and a major stress constraint to rice production throughout the world,which results in huge economic loss.Approximately one-fourth of the global rice crops(approximately 40 million hectares)are grown in rainfed lowland plots that are prone to seasonal flooding.A great progress has been made during last two decades in our understanding of the mechanisms involved in adaptation and tolerance to flooding/submergence in rice.In this review,we summarized the physiological and molecular mechanisms that contribute to tolerance of flooding/submergence in rice.We also covered various features of flooding stress with special reference to rice plants,viz.different types of flooding stress,environmental characterisation of flood water,impact of flooding stress on rice plant and their morphological,physiological and metabolic responses under flooding.A brief discussion on the tolerance mechanism in rice exhibited to different types of flooding will be focused for the future crop improvement programme for development of flooding tolerant rice variety.     

Molecular Improvement of Grain Weight and Yield in Rice by Using GW6 Gene

Molecular design breeding is one of straightforward approaches to break yield barriers in rice. In this study, GW6 gene for grain length and width from Baodali was transferred into an indica recurrent parent 9311 and a japonica variety Zhonghua 11 （ZH11） using marker-assisted backcross （MAB）. One and three introgression lines were selected for phenotypic analysis from 9311 and ZH11 genetic backgrounds, respectively. SSL-1, an improved 9311 near isogenic line with GW6 performed 11%, 19% and 6.7%higher of grain length, 1000-grain weight and single plant yield, respectively, as compared with 9311. All the three improved ZH11-GW6 lines, R1, R2 and R3, had more than 30% increase in grain weight and about 7%higher in grain yield. Seed plumpness of R1, R2 and R3 was improved synchronously because the three ZH11-GW6 lines contained GIF1 （Grain Incomplete Filling 1）, a dominant grain filling gene. Thus, GW6 has high potential in increasing the yield of inbred lines through MAB, making it an important genetic resource in super hybrid rice breeding. This study provides insights in the utilization of GW6 for large grain and high yield rice breeding via molecular design breeding.     

Genetic Dissection of Low Phosphorus Tolerance Related Traits Using Selected Introgression Lines in Rice

To dissect the genetic basis of low phosphorus tolerance(LPT), 114 BC2F4 introgression lines(ILs) were developed from Shuhui 527 and Minghui 86(recurrent parents), and Yetuozai(donor parent). The progenies were tested for 11 quantitative traits under three treatments including normal fertilization in normal soil(as control), normal fertilization in barren soil and low phosphorus stress in barren soil in Langfang, Hebei Province, China. Moreover, the ILs were investigated at the seedling stage using nutrient solution culture method in greenhouse in Beijing, China. A total of 49 main-effect quantitative trait loci(QTLs) underlying yield related traits were identified in Langfang, and their contributions to phenotypic variations ranged from 6.7% to 16.5%. Among them, 25(51.0%) QTLs had favorable alleles from donor parent. A total of 48 main-effect QTLs were identified for LPT-related traits in Beijing, and their contributions to phenotypic variations ranged from 7.7% to 16.6%. Among them, 21(43.8%) QTLs had favorable alleles from donor parent. About 79.6% of the QTLs can be detected repeatedly under two or more treatments, especially QTLs associated with spikelet number per panicle, spikelet fertility and 1000-grain weight, displaying consistent phenotypic effects. Among all the detected QTLs, eight QTLs were simultaneously identified under low phosphorus stress across two environments. These results can provide useful information for the genetic dissection of LPT in rice.     

灌浆期干旱胁迫对水稻生理性状和产量的影响

目的 研究灌浆期干旱对不同类型水稻叶片生理性状和产量的影响,为干旱气候条件下水稻栽培提供参考。方法 以节水抗旱稻旱优113和普通杂交稻扬两优6号(YLY6)为材料,设置传统淹水灌溉、灌浆期干旱胁迫两个处理,分别测定水稻的产量及产量构成、稻米品质(加工品质、外观品质和营养品质)、干物质生产及分配、叶片生理活性(叶片水势、气叶温差和光合速率)等。结果 与传统淹水灌溉相比,灌浆期干旱胁迫下水稻叶片水势、气叶温差均显著下降,最终导致叶片光合速率降低;但是在复水后2~15 d,叶片的各生理指标可以得到恢复,与对照没有显著差异;水稻产量没有明显变化,产量的稳定主要得益于前期充足的干物质积累使籽粒充分灌浆,结实率显著升高;稻米的碾磨品质没有显著影响,但扬两优6号的外观品质显著降低,却改善了旱优113的外观品质。同时,蛋白质含量升高在一定程度上改善了稻米营养品质。结论 水稻灌浆期适度干旱可以在稳定产量的基础上改善稻米品质。因此,适当在生育后期阶段减少水分的投入,不仅可节约农业用水,稳定籽粒产量,还有利于稻米品质的改善。