Effect of Environment and Genetic Recombination on Subspecies and Economic Trait Differentiation in the F_2 and F_3 Generations from indicajaponica Hybridization

indica and japonica are the two most important subspecies of Asian cultivated rice. Identifying mechanisms responsible for population differentiation in these subspecies is important for indica-japonica hybridization breeding. In this study, subspecies and economic trait differentiation patterns were analyzed using morphological and molecular （InDel and Intron Length Polymorphism） data in F2 and F3 populations derived from indica-japonica hybridization. Populations were grown in Liaoning and Guangdong provinces, China, with F3 populations generated from F2 populations using bulk harvesting （BM） and single-seed descent methods （SSD）. Segregation distortion was detected in F3-BM populations, but not in F3- SSD or in F2 populations. Superior performance was observed with respect to economic traits in Liaoning compared with that in Guangdong and 1 000-grain weight （KW）, seed setting rate （SSR） and grain yield per plant （GYP） were significantly correlated with indica and japonica subspecies types. Analysis of molecular and morphological data demonstrated that the environment is the main factor giving rise to population differentiation in indica-japonica hybridization. In addition, we also found that KW, SSR and GYP are related to subspecies characteristics and kinship, which is possibly a significant factor resulting in economic trait differentiation and determining environmental adaptability. Our study has provided new insights into the process of population differentiation in these subspecies to inform indica-japonica hybridization breeding.

Relationships of Panicle Type Index with Subspecies Characteristics and Yield Traits in Filial Generation of Crosses between Indica and Japonica Rice

Two recombinant inbred line （RIL） populations, one derived from a cross between Zhongyouzao 8 （indica） and Toyonishiki （japonica） and the other from a cross between Qishanzhan （indica） and Akihikari （japonica）, were grown in Liaoning and Sichuan Provinces, China, to study the panicle type index （PTI, the ratio of a number of node position on panicle axis where the secondary branch with the most numerous secondary branch grains is located to the number of primary branches） and its relationships with subspecies characteristics and yield traits. With continuous distribution of PTI and numerous of lines with different PTIs in the progenies, indica-japonica hybridization could be a method for breeding cultivars with ideal panicle type. PTI was significantly influenced by environments, with a significant decrease from Liaoning to Sichuan A significantly negative correlation was found between PTI and most of subspecies characteristics. PTI varied remarkably with different subspecies types. As a whole, it showed a trend of indica （H）〉indicalinous （H＇）〉japonicalinous （K＇）〉japonica （K） However, it is not appropriate to regard PTI as a parameter for subspecies classification in rice because it was recombined in the filial generations of cross between indica and japonica rice. The negative correlations were found between PTI and most of panicle characteristics, as well as yield-related traits. Based on PTI, most of lines from the two populations were middle dominant panicle type （the number of grains on the secondary branch is numerous in middle position of the panicle） and lower dominant panicle type （the number of grains on the secondary branch is numerous in lower position of the panicle and becomes less towards the top of panicle） with significant yield advantages.

The Relation between Genetic Difference for Parents of Hybrid Rice and Heterosis

Exploring the indica-japonica differentiation in parents of hybridization can provide theoretical bases for utilizing inter-subspecific heterosis. In this study, 5 sterile lines and 18 self-bred restorer lines were used as female parents and male parents respectively. Then 90 combinations were constructed by incomplete diallel cross followed by relationship analysis between parental Cheng’s index difference value and Euclidean distance and heterosis. The results showed a significant correlation between several phenotype values, super male parent heterosis and control heterosis and Euclidean distance or Cheng’s index difference value. However, it was no significant correlation for yield. Further analysis found a common interval, 3.41 - 3.46 for Euclidean distance and 3 - 4 for cheng’s index difference value of parents, which was significant or high significant positive correlated with phenotype value, super male parent and control heterosis of main yield traits. This illustrates that the larger the genetic difference of parents was, the stronger the heterosis combinations were, when the genetic differences of parents were in an appropriate range.

Genetic analysis of morphological index and its related taxonomic traits for classification of indica/japonica rice

A doubled haploid population derived from anther culture of ZYQ8/JX17 F1, a typical indica and japonica hybrid, was used in this study. Morphological index and its related taxonomic traits were investigated in 121 DH lines. The quantitative trait loci (QTLs) for morphological index and its related taxonomic traits were analyzed. Two major QTLs for leaf hairiness, three QTLs for length/width of grain, one QTL for color of hull when heading, one QTL for hairiness of hull, two QTLs for length of the first and second panicle internode, and one major QTL and two QTLs for phenol reaction were detected. Four QTLs for morphological index were also identified on chromosomes 1, 3, 4 and 6, respectively, three of which on chromosomes 1, 3 and 6, respectively, were found to be located in the same chromosome regions where some QTLs for the related taxonomic traits were located.

QTL analysis of the rice seedling cold tolerance in a double haploid population derived from anther culture of a hybrid between indica and japonica rice

A doubled haploid population, derived from anther culture of F hybrid between a typical indica cv. and a japonica cv. has been used to investigate the seedling cold tolerance (SCT) in growth cabinet. By dynamically analyzing every day’s survival percentages of the parents and DH lines under 7-d cold plus 9-d normal temperature condition, the guantitative trait loci (QTLs) for SCT have been mapped based on a molecular linkage map constructed from this population. The results show that two parents had significant differences in SCT and the segregation of SCT in DH lines was basically a continuous distribution with most serious injury on the 6th d of the cold treatment. A total of 4 QTLs for SCT have been identified on chromosomes 1, 2, 3 and 4 respectively. The additive effects of qSCT-1, qSCT-2 and qSCT-3 have been contributed by the japonica ev JX17, but that of qSCT-4 has been contributed by the indica cv ZYQ8. The mechanism of SCT seems complicated since the above 4 QTLs detected at different stages

Genetic Characterization of Indigenous Rice Varieties in Eastern Himalayan Region of Northeast India

The eastern Himalayan region of Northeast （NE） India is home to a large number of indigenous rice varieties, which are traditionally classified as Oryza sativa subspecies indica, japonica or intermediate types. The classification based on traditional Cheng’s index is often inconclusive due to phenotypic plasticity of morphological characters, which are influenced by environmental conditions. We used molecular markers specific for indica and japonica subspecies to assess the degree of genetic relatedness of indigenous rice varieties in NE India. The results revealed that majority of upland （jum） and glutinous rice varieties, traditionally considered as japonica, were genetically close to the subspecies indica. All varieties of boro ecotype were found to be indica type, and only a few varieties cultivated in lowland and upland areas were japonica type. Some of the lowland varieties of the sali ecotype were intermediate between indica and japonica, and they showed a closer genetic affinity to O. rufipogon.

水稻穗颈维管束性状的类型间差异及其遗传的研究

1987～1990年以包括典型粳型、典型籼型、通过籼粳稻杂交育成的偏粳型和偏籼型4种类型共68个品种为试材,研究了穗颈维管束性状的类型间差异及其遗传。结果表明:无论亚种间还是不同亚种的类型间,穗颈大维管束数均存在显著差异,而亚种内类型间的差异则未达到显著水平;穗颈小维管束数亚种间差异不显著,但亚种内类型间有一定差异;第2节间与穗颈大维管束数之比和穗颈大小维管束数之比的变异趋势与穗颈大维管束数相似,而且较后者更为稳定,可作为籼粳亚种分类的2个参考解剖指标;籼粳亚种间杂交,穗颈大维管束数在F_1接近双亲平均值,F_2呈连续变异,接近正态分布,正反交F_1表现和F_2分离均无显著差异。

籼粳稻杂交育成品种的亚种特征性状及其与经济性状的关系

采用程氏指数法研究的结果表明 :95个籼粳杂交育成水稻品种均划入粳型或偏粳型 ;6项亚种特征性状中穗壳色、酚反应、稃毛、叶毛及籽粒长宽比全部或大多表现典型粳型特性 ,少量为中间型或偏向籼型 ,穗节长表现中间类型最多 ,极少数为籼型和粳型 ;籼粳杂交F1 和育成品种的程氏指数和亚种特征性状与经济性状关系不密切 ,而F2 的相关性明显增大 ;

不同生态条件下籼粳稻杂交后代亚种特性的比较研究

以中优早8号×丰锦F6重组自交系群体为试材,在辽宁和四川两个不同的生态区种植,研究亚种特性的变化。结果表明,试材在两个地区都呈偏粳分布。不同生态条件下亚种特征性状发生了明显变化,总体上四川表现比辽宁更加偏粳。进一步分析显示,籼及偏籼型四川比辽宁表现更加偏籼,而粳及偏粳型更加偏粳。生态条件对程氏指数6性状的影响因性状而异,1-2穗节长、叶毛四川比辽宁偏粳,籽粒长宽比、抽穗时壳色四川比辽宁偏籼。生态条件对程氏指数6性状间和程氏指数与维管束性状间的相关性也有显著影响。籼粳稻杂交后代的维管束性状在不同生态条件下有显著变化,四川穗颈大维管束数比辽宁明显减少,而穗颈小维管束数和第二节间小维管束数明显增加,大小维管束比降低,大维管束比增加。总体上虽然有大小维管束比籼型>粳型,大维管束比籼型<粳型的趋势,但是大小维管束比和大维管束比不能作为籼粳稻分类的指标,籼粳稻杂交后代亚种特性与维管束性状已经重新组合。

水稻籼粳亚种间杂种优势利用研究进展

本文从水稻育种进步的宏观观点,回顾与展望了我国水稻杂种优势利用的历史进程。由早期追求以强大生物优势为主要育种目标的启蒙阶段进入三系法生态远缘优势与理想株型相结合的籼梗杂种优势间接利用阶段,实现了水稻杂种优势利用的第一次飞跃。现在又进入三系法、两系法籼粳有利基因交换与自由配组的籼梗杂种优势直接利用阶段,预期将产生水稻杂种优势利用的第二次飞跃。近年研究表明,双亲遗传距离与经济优势呈二次多项式关系,杂种优势含可利用与非可利用两个方面,广亲和系可以将亚种F_(?)结实率提高到正常水平,但它的稳定性受双亲遗传背景与环境互作影响。因此,采用“籼梗(爪)架桥”,亲缘渐渗,有利基因交换,亲本遗传改良以及因地制宜选择种植区,是籼粳亚种间杂种优势利用的主要方法。

籼粳稻杂交后代蒸煮食味品质与亚种分化的关系

以2个典型籼粳稻杂交重组自交系F8群体(中优早8号×丰锦,计158株系;七山占×秋光,计142株系)为试材,利用程氏指数法鉴别其籼粳属性,同时测定稻米食味品质及淀粉RVA特征值,分析籼粳杂交后代稻米蒸煮食味品质与籼粳亚种性状特征的关系。结果表明:1)2个群体程氏指数、口感、综合评分及RVA谱特征值均呈连续分布,大部分株系介于双亲值之间;2)程氏指数与口感、综合评分及各RVA谱特征值的相关不显著或相关系数较小,依据程氏指数划分的类型间口感、综合评分及RVA谱特征值无明显差异,说明籼粳分化对稻米食味品质无直接影响;3)随着口感改善和综合评分的提高,热浆黏度、冷胶黏度、消减值降低、回复值升高,其他RVA谱特征值变化规律性不明显。

生态环境对籼粳稻杂交后代穗部性状的影响及其与亚种特性的关系

【目的】探讨生态环境对籼粳稻杂交后代穗部性状的影响及其与亚种特性的关系。【方法】以辽宁育成的两个典型的籼粳交重组自交系F6群体(RIL1:中优早8号/丰锦、RIL2:七山占/秋光)为试材,分别在四川和辽宁同年种植,研究穗部性状和亚种特性变化规律及其相互关系。【结果】穗部形态、解剖性状与亚种特性都发生了极显著的变化。从辽宁到四川,穗颈粗和穗颈大维管束数极显著减少,第二节间小维管束数和大维管束比极显著增加,结实率特别是二次枝梗结实率极显著下降,程氏指数更加偏粳。穗颈大维管束数、大小维管束比、大维管束比、结实率和千粒重在亚种类型间差异显著。穗颈节间维管束数目与穗"库"结构性状呈极显著正相关,与籽粒充实特性相关不显著;相反,亚种特性与穗"库"结构性状相关不显著,而与籽粒充实特性呈极显著的正相关。【结论】生态环境对籼粳交后代的穗部性状有极显著的影响。依穗颈粗去选择维管束性状是一条切实可行的途径。穗颈大维管束数、籽粒充实特性、程氏指数三者之间互相制约,北方的育种者要在实践中统筹兼顾。

“Lemont/特青”重组自交系的六性状籼粳分类研究

研究了287个“Lemont／特青”重组自交系的六个籼粳分类性状（程氏指数法）和154个RFI．P位点的遗传组成。群体的六性状总分呈连续分布，略偏向粳型，该方法将把大部分株系分入籼粳中间类型。遗传组成的分布略偏向特青并有更多的极端株系，六性状总分和分子标记的相关不明显。还就单个性状的分布和性状间重组情况，以及不同性状间及其与总分间的相关关系进行了分析。

基于SSILP、InDel和SSR标记的杂草稻籼粳分类

采用40对SSILP、30对InDel和43对SSR标记对来自斯里兰卡的28份杂草稻和14栽培稻,来自国内外的9份籼型栽培稻、7份粳型栽培稻和4份代表性杂草稻进行遗传多样性分析。SSILP、InDel和SSR标记分别检测到84、61和213个等位基因,其平均多态性信息含量(PIC)分别为0.257、0.255和0.543。聚类分析显示供试的42份斯里兰卡杂草稻和栽培稻均为籼型。SSILP与InDel标记的相关性很高(r=0.989),而它们与SSR标记相关性较低(0.812和0.808)。结果表明,SSILP和InDel标记可高效鉴别各类稻种资源的籼粳属性,而SSR标记更适用于亚种内的分类。

籼粳稻杂交分类性状遗传研究初报

应用程氏指数法研究了不同类型杂交组合。结果表明：粳×籼Ｆ１为偏籼型，Ｆ２呈正态分布，大部分为籼粳中间型。粳×爪Ｆ１为偏粳型， Ｆ２为偏粳型和粳型。粳×粳Ｆ１与Ｆ２均为粳型。程氏指数法叶毛、稃毛、 穗壳色、ｉ～２穗节长、籽粒长宽比、酚反应６个分类性状间相关密切，对总分均有较大贡献，适于分析籼粳交Ｆ２以后各世代。粳×籼Ｆ２代各性状的分离除酚反应为双峰曲线外，其它５个性状均呈单峰曲线分布；除穗节长性状具有超亲现象外，其它５个性状均介于双亲之间，为部分显性。抽穗期与亲本及Ｆ１程氏指数呈极显著的负相关，结实率与Ｆ２程氏指数呈极显著的负相关。

利用粳型广亲和恢复系与籼稻不育系配制籼粳亚种间杂种

对用粳型恢复系与广亲和系02428杂交选育出的一批农艺性状稳定的新的粳型恢复系进行亲和性和恢复力测定。结果表明,在所测定的9个株系中,有1个株系(87-3)能使协青早A和庆莲16A的育性恢复到69.6％和63.6％,有6个株系(87-1、87-3,87-4、87-6、87-7,87-8)能使六南早A的育性恢复到60％以上。杂种生长繁茂,穗粒优势十分明显,与品种间杂种相比具有更大的生产潜力。讨论了基于广亲和恢复系选育的三系法籼粳亚种间杂种优势利用的可能性及其育种价值。

江苏省杂草稻的传播与籼粳分化研究

21世纪初,杂草稻仅在江苏省局部区域发生,目前已扩大到全省,并对粳稻的高产和稳产造成严重威胁。为了掌握其快速发生机制,便于杂草稻的防除工作,需要进一步明确江苏省13市杂草稻是独立发生还是相互传播,以及江苏省杂草稻籼粳地理分布。采集了江苏省13个市58个样地的58个种群,总计205份的杂草稻样品。所有样品在南京农业大学江浦农场田间种植,并测量了38个形态学性状和6个程氏指数鉴别性状。欧氏距离聚类分析,表明江苏省13个市的杂草稻是相互混杂的。籼粳地理分布表明,江苏省杂草稻主要以籼型和偏籼型为主,籼型和偏籼型杂草稻在全部58个样点中都有分布,分别占样品总量的54.15%和42.40%;偏粳型和粳型仅分布于6个样点(淮安、苏州、盐城与扬州),分别占样品总量的2.93%和0.48%。此外,对比江苏省杂草稻的籼粳地理分布与江苏省地方品种的籼粳地理分布,未显示对应关系。籼粳比例和地理分布揭示了江苏省杂草稻主要为籼型,其中极少数为粳型杂草稻,粳型杂草稻的比例与杂草稻和栽培稻之间的自然基因漂移比例相近。

籼、粳稻及其杂种谷粒苯酚染色反应研究

用典型籼稻和粳稻进行双列杂交并与不同籼粳成分的重组自交系杂交研究籼、粳稻及其杂种谷粒酚反应,结果表明:水稻谷粒的苯酚染色反应是由基因控制的性状,染色对不染表现为显性;典型粳×粳交F1表现为不染,而籼×籼交F1、籼×粳交F1和粳×籼交F1表现为黑染或褐染;在含不同籼粳成分的9个重组自交系(RILs)稳定品系中,籼型和偏籼型品系表现为典型籼型染色反应(黑染)的特点,而偏粳型和一个偏籼型品系则表现为典型粳型染色反应(不染)特点。利用酚反应难以鉴别籼粳交后代的籼粳特性,也难以用于籼粳稻杂交种子的测纯。

普通野生稻遗传分化及水稻起源关系研究进展

普通野生稻是亚洲栽培稻的祖先种,但关于水稻籼、粳两个亚种的起源演化途径一直存在争议。最近的研究认为,粳稻起源于广西珠江流域的普通野生稻,因此普通野生稻及其内部的遗传分化在研究栽培稻起源过程中起着重要的推动作用。文章结合野生稻的形态、分子标记鉴定以及基因测序等研究结果,全面论述普通野生稻在农艺性状、籼粳遗传分化等方面与栽培稻的演化途径、起源地和起源次数的关系,为揭示栽培稻的起源及进化过程提供更多参考依据。同时建议在高通量测序等技术的基础上扩大普通野生稻群体和个体数量的检测,特别是重点地区普通野生稻和地方品种,深入了解其遗传变异、结构特点等,并结合考古线索进行分析,进一步挖掘栽培稻起源演化的依据和线索。

利用分子标记辅助选择培育水稻广亲和保持系

【目的】利用分子标记辅助选择培育水稻广亲和保持系,为水稻籼粳亚种杂种优势利用提供参考。【方法】用4个不育系博A、天A、青A、62A与24个水稻姊妹系杂交,测定其恢保性;同时利用与S5n紧密连锁的SSR标记GXR6对24个姊妹系进行检测;再通过籼粳测交验证其亲和性。【结果】24个姊妹系中除B11、B13、B14、B15外,其余B1-B10、B12、B16-B24等20个姊妹系花粉不育度均达100.0%,对4个不育系博A、青A、天A、62A均保持不育。SSR分子标记检测结果显示,B1、B2、B4-B7、B10-B12、B14-B16、B18-B20、B22、B23等17个姊妹系均携带187R的广亲和基因S5n;但与日本晴和巴利拉测交验证结果显示,仅B1、B4具有亲和性,B9虽未携带S5n却具有亲和性,其测交组合F1代植株结实率极显著高于桂B测交的结实率（P〈0.01）而低于测验种自身的结实率（桂B结实率79.79%,日本晴76.87%,巴利拉73.65%）,B1、B4和B9属于中亲和力品系。【结论】筛选获得的广亲和保持系B1、B4和B9,可用来改造现有不育系,充分发挥籼粳亚种杂种优势,提高杂交水稻产量,具有较好的应用前景。