Characterization and evaluation of rice blast resistance of Chinese indica hybrid rice parental lines

The development of resistant varieties and hybrid combinations has been the most effective and economical strategy to control blast disease caused by Magnaporthe oryzae.However, the distribution of major R genes and blast resistance characterization in hybrid rice parents has not been well investigated, resulting in their limited use in hybrid rice blast-resistance breeding. In the present study, 88 elite indica hybrid rice parental lines were evaluated with 30 isolates of M. oryzae collected from the main planting area of indica hybrid rice in China and were characterized for the presence of 11 major resistance genes using molecular markers. The pathogenicity assays showed that four types of hybrid rice parent line showed some resistance to M. oryzae. However, the proportions of highly resistant lines and the mean resistance frequency(RF) varied among the four types, with resistance in decreasing order shown by three-line restorer lines, three-line maintainer lines, two-line sterile lines, and two-line restorer lines. All 88 hybrid rice parental lines carried more than one R gene, but none carried the R genes Pi1 and Pi2. Although Pid3 and Pi9 were present only in three-line restorer lines and Pigm only in three-line maintainer lines, the remaining six R genes(Pib, Pid2, Pi5, Pia, Pi54, and Pita) were present in the four types of hybrid rice parent with significantly different distribution frequencies. The correlation between R genes and resistance reactions was investigated. The results are expected to provide useful information for rational utilization of major R genes in hybrid rice breeding programs.

Genetic Diversity among Parents of Hybrid Rice Based on Cluster Analysis of Morphological Traits and Simple Sequence Repeat Markers

The genetic diversity of 41 parental lines popularized in commercial hybrid rice production in China was studied by using cluster analysis of morphological traits and simple sequence repeat （SSR） markers. Forty-one entries were assigned into two clusters （i.e. early or medium-maturing cluster; medium or late-maturing cluster） and further assigned into six sub-clusters based on morphological trait cluster analysis, The early or medium-maturing cluster was composed of 15 maintainer lines, four early-maturing restorer lines and two thermo-sensitive genic male sterile lines, and the medium or late-maturing cluster included 16 restorer lines and 4 medium or late-maturing maintainer lines. Moreover, the SSR cluster analysis classified 41 entries into two groups （i.e, maintainer line group and restorer line group） and seven sub-groups. The maintainer line group consisted of all 19 maintainer lines, two thermo-sensitive genic male sterile lines, while the restorer line group was composed of all 20 restorer lines. The SSR analysis fitted better with the pedigree information. From the views on hybrid rice breeding, the results suggested that SSR analysis might be a better method to study the diversity of parental lines in indica hybrid rice.

Parental Selection in Rice Cultivar Improvement

The evaluation of rice （Oryza safiva L.） cultivars assists breeders in identifying useful trait relationships and in selecting parents as donors of specific traits. This study was conducted to compare long-grain rice cultivars using genotype x trait （GT） biplot analysis and determine potential donors of traits related to grain yield and quality. Seventeen cultivars in the 2005 and 2006 Uniform Regional Rice Nursery in Beaumont, Texas, USA were analyzed for 20 traits using GT biplot analysis. The GT biplots showed the diversity among cultivars with regards to yield-related traits. Cultivars recommended as donor parents were： Trenasse, Spring, Presidio, and Cocodrie for high grain yield and head rice rate Trenasse and Presidio for semi-dwarfness; Banks for tall plant height; Wells for high flag leaf area, panicle weight, and number and mass of filled grains per panicle; Hidalgo for high tiller density; Francis for high number of spikelets per panicle; Spring and Trenasse for short flowering duration; Cheniere for more days to heading and maturity and Spring for less days; and Spring and Hidalgo for high grain weiqht. Breeders can use these cultivars with specific traits to increase qrain yield and quality.

Free amino acid (FAA) analysis of phloem sap in hybrid rice Shanyou 63 and its parents

Hyhrid rice has greatly contributed to rice production inChina. But concurrently a dramatic upsurge of rice plant-hopper occurred, particularly for the whitebacked plant-hopper (WBPH), Sogatella furcifera. It has become animportant economic insect pest of hybrid rice, although ithad only been a minor herbivore of rice before nation-wideexploitation of hybrid rice.

优异常规粳稻亲本组合选配方法及其育种应用

【目的】在了解表型与基因型差异的基础上同时对候选常规粳稻亲本进行分类,随后结合育种亲本选配四大原则进行优异亲本选配,为常规粳稻育种提供一种亲本组合选配方法。【方法】以江苏省自主选育水稻品种为材料,考察34个品种的42个表型性状,并利用41对SSR标记对以上34个品种进行基因型鉴定。通过表型值与基因型值分别计算欧几里得距离、遗传相似系数,采用Ward.D法、UPGMA法进行聚类分析。【结果】农艺性状、品质性状的遗传相似性分析表明,大部分试验品种的遗传基础背景比较相近,但SSR标记的遗传相似性分析显示34个品种的遗传相似系数在0.39~0.95,表明江苏不同单位育成的品种遗传背景仍存在不同。聚类分析结果表明,不同类群间农艺性状、品质、等位基因差异与不同生态型不存在明显关系。AMOVA分析显示试验品种96.19%的遗传变异来源于群体内。【结论】不同聚类结果得到的类群不完全一致,将农艺性状、品质性状、SSR标记的聚类结果结合起来对亲本进行分类更有利于增加亲本选配的精确度、减少育种工作量、提高育种效率。本研究应用多种指标聚类方法进行常规粳稻亲本选配,在镇稻18号与盐稻11号组合中,选育出大量优异中间材料,并育成了不同生态型新品种镇稻23号、镇稻32号和镇稻33号。

珠江三角洲铊在水稻籽实-根系土间迁移及人体健康风险评价

铊(Tl)是一种典型的剧毒重金属元素,其环境行为及人体健康效应日益得到广泛关注,土壤Tl富集会对土壤环境、农作物生长及人体健康造成严重的危害性。珠江三角洲作为土壤重金属富集的典型区域,当前研究主要聚集于Cu、Cd、Pb和As等元素,而对土壤Tl的地球化学特征及其影响因素、生物富集能力及人体健康效应评价的研究较少。本文以珠江三角洲3种成土母质分布区的243套水稻籽实及其根系土样品为研究对象,揭示了水稻根系土Tl含量、生物富集特征及其影响因素,并采用美国环保署(US EPA)推荐的人体健康风险评价模型对研究区土壤Tl的人体非致癌健康风险进行评价。结果表明:水稻根系土Tl含量显著高于我国和广东省土壤Tl含量背景值,18.1%的水稻根系土Tl含量超过加拿大Tl环境质量标准值及瑞士农业土壤Tl标准值(1×10^(-6))。酸性岩浆岩与第四纪沉积物分布区水稻根系土Tl超标率明显高于陆源碎屑岩。水稻根系土Tl含量表现出与K_(2)O、Al_(2)O_(3)、Pb和Zn含量显著相关。综合分析认为珠江流域硫化物矿床风化剥蚀及开采活动是导致下游平原区土壤Tl等重金属元素富集的主要原因。全区20件水稻籽实Tl含量的平均值为0.35×10^(-3),均远低于德国食品安全规定的Tl可食用标准值,水稻籽实Tl生物富集系数主要与根系土Na_(2)O、Zn和Pb含量显著相关。每个样点的HQ值分级结果显示,研究区68%的儿童有中等健康风险,46%的成人有中等健康风险,儿童健康风险显著高于成人。

Practices and Prospects of Super Hybrid Rice Breeding

The great progress in super rice breeding both in China and other countries has been made in recent years. However, there were three main problems in super rice breeding： 1） the super rice varieties were still rare; 2） most super rice varieties exhibited narrow adaptability; and 3） current breeding theories emphasized too much on the rice growth model, but they were unpractical in guidance for rice breeding. According to the authors＇ experience on the rice breeding, the breeding strategies including three steps （super parent breeding, super hybrid rice breeding and super hybrid rice seed production） were proposed, and the objectives of each step and the key technologies to achieve the goals were elucidated in detail. The super parent of hybrid rice should exhibit excellent performance in all agronomic traits, with the yield or sink capacity reached the level of the hybrid rice control in regional trials. The super hybrid rice combination should meet the following criteria： good rice quality, wide adaptation, lodging resistance, resistance to main insects and diseases, and the yield exceeded above 8% over the control varieties in the national and provincial regional trials. To achieve the goal, the technical strategies, such as selecting optimal combination of the parents, increasing selection pressure, paying more attention to harmony of ideal plant type, excellent physiological traits and all the agronomic traits, should be emphasized. The yield of seed production should reach 3.75 t/ha and 5.25 t/ha for the super hybrid rice combinations derived from early-season and middle-season types of male sterile lines, respectively. The main technologies for raising seed production yield included selecting optimum seed production site, using the male sterile line with large sink capacity and good outcrossing characteristics, and improving the amount of the pollen by intensive cultivation of the male parent. According to the technologies of the three-step breeding on super hybrid rice, two super rice parents, including a male parent 996 and a thermo（photo）-genic male sterile [T（P）GMS] line C815S, were bred. Furthermore, a super early hybrid rice combination, Luliangyou 996, which could be used as a double-season early rice variety in middle and lower reaches of the Yangtze River, China, was bred by using the super rice varlet3, 996 as the male parent, and several hybrid rice combinations with higher yield than control variety in regional trials both of Hunan Province and state were bred with the T（P）GMS line C815S as the female parent.

Analysis of Genetic Similarity for Improved Japonica Rice Varieties from Different Provinces and Cities in China

To provide a genetic basis for japonica rice breeding, the genetic similarity and cluster of 139 accessions of improved japonica rice varieties from 12 provinces and cities of China were analyzed using 34 SSR markers. Totally 198 alleles were detected among these improved japonica rice varieties with the average number of alleles per pair of primers was 5.3235. RM320, RM531, RM1, RM286, and RM336 showed more alleles, which were 15, 12, 11, 9, and 9, respectively. RM320, RM336, RM286 and RM531 showed higher genetic diversity indexes; which were 2.3324, 2.0292, 1.8996, and 1.7820, respectively. The range of genetic similar index among improved japonica rice varieties from different provinces was from 0.321 to 0.914, with the average of 0.686. There was a high genetic similarity among improved japonica rice varieties from Heilongjiang, Jilin, Liaoning, Ningxia, and Yunnan, which were located in similar latitude or similar ecological environment, while there was a low genetic similarity between improved japonica rice varieties from Guizhou and Jiangsu, and other provinces which were located in more different latitudes and ecological environments. The markers of RM320, RM531, RM1, RM286, and RM336 fit to be used in analysis of genetic diversity for improved japonica rice variety. The genetic similarity among improved japonica rice varieties from different provinces was closely associated with genetic basis of parents, and was also correlated with latitude and ecological environment where the varieties were bred.

杂交粳稻申优28全程机械化高产高效制种技术研究

申优28是以BT型不育系申21A与恢复系申恢26-28配组育成的三系杂交粳稻新组合。申优28制种时,通过调节双亲的生长发育,确保了父母本花期高度相遇。研究了父母本均机插条件下不同父母本行比及母本株距对申优28制种产量的影响,以及在父本机插(行距25cm)-母本机直播(行距20 cm)条件下,母本不同株距对申优28制种产量的影响。结果表明,在父母本均机插条件下,父母本行比2︰8~10、行株距25 cm×14 cm时制种产量高;父本机插-母本机直播条件下,以株距16 cm时制种产量高。通过以上优化栽培方式,确保了杂交粳稻制种高产高效。

南方稻区主栽香稻品种香味基因Badh2基因型分析

【目的】香味是水稻重要的品质性状之一,直接影响消费者对稻米蒸煮食味的感官评价。香稻资源的筛选和香味基因的鉴定与利用对香稻遗传育种以及香稻产业发展具有一定的实践意义。Badh2是目前已被克隆的控制水稻香味的主效基因,明确该基因不同突变类型在南方地区香稻主栽品种中的分布与利用程度,可更好地服务于南方稻区的香稻育种研究。【方法】利用香味基因Badh2的KASP功能性分子标记,对30份南方香稻主栽品种Badh2进行基因分型分析,并采用咀嚼法、KOH浸泡法、HS-SPME/GC-MS联用技术对以上香稻品种进行香味表型鉴定,同时对主栽香稻品种的香源亲本进行溯源分析。【结果】KASP分子标记可准确地对香味基因Badh2进行基因分型,南方稻区种植推广的30份香稻品种Badh2等位变异基因分型结果均为Badh2-E7型突变,并且利用多种香味检测方法鉴定以上香稻均具有香味。对香稻品种的香源亲本溯源分析发现,南方稻区香稻品种香源亲本来源比较单一,主要是包括象牙香占、Basmati 370等,其中以象牙香占为香源亲本占比约30%,以Basmati 370为香源亲本占比约13%。【结论】通过KASP基因分型技术可实现对香稻进行大批量快速鉴定,本研究中所涉及的南方主栽香稻品种的Badh2等位基因型均为Badh2-E7型,香味基因基因型背景较为单一,可能与香源亲本来源单一有关。未来在南方稻区的香稻育种中,可以适当引入新的香味基因,丰富香味基因的遗传背景,培育更多香味类型的香稻品种。

分子标记辅助选择改良南粳5055米香性状的研究

为进一步提高优良食味水稻品种南粳5055蒸煮食味品质,利用分子标记辅助选择,将米香基因badh2成功导入南粳5055中。在分子标记对目标基因进行前景选择的同时,利用《NY/T 1433-2014》推荐的48个以及作者实验室筛选的31个SSR标记进行背景检测;在BC3F2世代,筛选出遗传背景与轮回亲本一致的单株,结合农艺性状筛选及品质分析,获得所考察性状与南粳5055一致且携带米香基因的南粳5055新品系;并就背景选择中不同来源分子标记对江苏粳稻品种的鉴别力问题进行了讨论。

杂交水稻亲本遗传差异及其与杂种优势关系

以目前生产上大面积应用和新育成的16个籼型三系杂交水稻亲本为材料，根据11个主要农艺和经济性状进行主成分分析和聚类分析，以马氏距离为指标，研究了杂交水稻亲本间遗传差异的状况及其与杂种优势的关系。在16个亲本的120个遗传距离中，80％以上小于2；9个恢复系间的平均遗传距离仅为0．4793，7个保持系间，除湘香2号B外，平均遗传距离为0．7723。说明现有杂交稻亲本间遗传差异较小，尤其是保持系内和恢复系内遗传差异更小。对亲本间遗传距离与杂种优势的相关分析表明，现有籼型三系杂交稻亲本间遗传差异与杂种优势关系不密切，而杂交稻产量的高低与双亲产量尤其是双亲产量平均值的高低密切相关。说明亲本改良在提高杂交稻产量中极为重要。此外，还对亲本改良与杂种优势的关系、杂交相亲本改良的方法和途径以及杂交稻组合亲本选配原则进行了讨论。

杂交水稻亲本分子身份证及SSR指纹数据库的建立

本研究利用GB/T20396-2006推荐的48对SSR核心标记,对133份杂交水稻亲本(包括部分常规品种)进行SSR分析,根据引物在133份材料中扩增的片段大小,构建了各品种的分子身份证和指纹图谱,该身份证由48位数字或数字与字母组合组成,代表了48对引物在该品种中的扩增情况。将品种的身份证信息与品种的形态学特征特性等信息相结合,构建了具查询功能的SSR指纹网络数据库。该SSR指纹数据库除具有品种基本信息查询、品种分子身份证查询、品种间相似率查询和身份证核对等基本功能外,还可指导杂交水稻品种真实性和纯度鉴定,分析亲本间遗传相似性,为杂交稻新组合的选育提供亲本选配的参考。该数据库的建立,不仅为检测单位和育种工作者提供了一个便利的网络数据交换和共享平台,也为品种的选育、试验、管理、评价、仲裁提供技术支撑和科学参考。

Cd胁迫对杂交水稻及其亲本叶片丙二醛含量的影响

以15份杂交水稻及其亲本为材料,采用水培试验研究了不同Cd2+浓度胁迫对水稻叶片丙二醛(MDA)含量的影响。结果表明:(1)在不同Cd处理水平和生育时期,保持系叶片MDA含量存在差异,如D83B叶片MDA含量各处理显著高于对照(p<0.05),MDA积累水平较高,受到Cd严重胁迫,而Ⅱ-32B在两个生育时期受低Cd浓度的影响不大,与对照差异不显著,且随着Cd浓度的增大,MDA含量均表现出较低的MDA积累水平,因此保持系Ⅱ-32B是一种较好的保持系材料。(2)Cd胁迫对恢复系各材料叶片MDA的影响不同,其中以R527、R498叶片MDA积累最明显,孕穗期和灌浆期各处理均显著高于对照,其余恢复系材料受不同Cd2+浓度的影响,MDA积累不稳定。(3)同一保持系(Ⅱ-32B)与不同恢复系(R498、R549、R892)组合配制的3个杂交稻叶片在MDA含量的增加幅度上表现不同,其中Ⅱ优498、Ⅱ优892受Cd影响较小,无论在孕穗期还是灌浆期叶片MDA含量增幅相对较小,而Ⅱ优549受Cd严重胁迫,各处理均显著高于对照,MDA积累增幅最大。(4)同一恢复系(R498)与不同保持系(Ⅱ-32B、D62B)配制的杂交稻叶片MDA含量亦不同,如D优498仅在孕穗期低浓度下MDA较对照有所降低,其余各处理MDA均积累较多,而Ⅱ优498MDA含量随着Cd浓度的增加,MDA增幅相对较小,可见水稻亲本对子代MDA的积累存在差异,可根据优良亲本,寻找优势组合,培育出抗Cd性强的杂交水稻。

杂交水稻苗期耐淹涝特性及其与亲本的关系

经对生产上主栽的野败型三系杂交组合及其亲本苗期耐淹涝能力的比较研究 ,杂交稻的耐淹涝能力的平均优势明显 ,且以显性效应为主。恢复系效应大于不育系 ;杂交稻淹涝后生存率与恢复系呈极显著正相关 ,与不育系呈显著正相关。杂交稻的耐淹涝表现以偏父型和中间型为主 (80 %以上 ) ,偏母型比例低。恢复系、不育系耐淹涝能力强的 ,配出的杂交稻耐淹涝能力更强。

杂交水稻产量性状配合力研究

利用 9个不育系和 7个恢复系配制 40个杂交组合 ,对 6个产量性状的亲本一般配合力和组合特殊配合力效应进行分析。结果表明 ,杂种一代 (F1)各性状的形成同时受亲本一般配合力和组合特殊配合力的影响。单株穗数、每穗总粒数、千粒重三性状主要受一般配合力作用 ;每穗实粒数、结实率、单株粒重三性状则一般配合力和组合特殊配合力的作用同样明显 ,或特殊配合力作用更明显些。不育系珍汕 97A、龙特浦A、K1 8A和恢复系明恢 63、直龙、1 0 2 5的一般配合力高 ,利用它们容易配制出高产组合。两年试验结果千粒重、单株粒重二性状的形成均是不育系的作用大于恢复系 ,近期育种工作重点应放在不育系的选育上。

亲本抗瘟性对杂交水稻组合抗瘟性的影响

利用6个三系不育系与4个抗瘟性不同的恢复系按不完全双列杂交设计配制24个杂交稻组合,对其进行病圃穗颈瘟鉴定,并用60个来自四川和重庆主栽品种的稻瘟病菌ZA、ZB群菌株进行抗谱测定。结果表明,杂交稻组合的抗瘟性与其相应恢复系的抗瘟性密切相关,恢复系的抗瘟性越强,其所配杂交稻组合的抗瘟性也越强。不育系的抗瘟性差异对杂交稻组合的抗瘟性有一定影响,说明杂交稻组合的抗瘟性受恢复系和不育系抗瘟性的共同影响。由于目前生产上使用的主要不育系都感稻瘟病,杂交稻组合的抗瘟性主要受恢复系的抗瘟性影响。因此,目前为提高杂交稻抗瘟性,育种上应以提高恢复系抗瘟性为重点。同时,利用恢复系抗瘟性的变化动态可以间接监测杂交稻组合的抗瘟性变化动态。

采用表型和分子标记聚类研究杂交籼稻亲本的遗传多样性

以41份杂交籼稻骨干亲本和部分新育成的亲本为试验材料,采用表型性状和SSR分子标记2种聚类分析方法对杂交籼稻亲本的类群划分进行了比较研究,表型聚类以15个表型性状为依据,将供试材料划分为早、中熟和中、晚熟两大类群、6个亚群。早、中熟类群包含15个保持系、4个早熟恢复系和2个温敏核雄性不育系;中、晚熟类群包括16个恢复系和4个中、晚熟保持系。利用SSR分子标记将供试材料划分为保持系和恢复系两大类群、7个亚群。保持系群包括全部19个保持系、2个温敏核雄性不育系,恢复系群则包含全部20个恢复系,分类结果和系谱分析基本吻合。结合杂交籼稻育种实践,判断分子标记可能是研究亲本遗传多样性的一种较好方法。

水稻亲本对所配组合的米质性状影响

应用9个不育系和6个恢复系通过不完全双列杂交进行配组,所得的54个组合和这6个恢复系即为本文的研究材料,就它们的出糙率、整精米率、垩白粒率、垩白度、直链淀粉<干基>、胶稠度和粒型<长宽比>这7项米质指标进行了分析。结果表明,不同不育系组配的组合系列间的7项米质性状差异最大,多数达到了极显著水平。不同恢复系组配的组合系列间的7项米质性状之间差异较小,多数差异不显著;而恢复系本身之间的7项米质性状差异却较大。说明恢复系本身的米质特征在所配组合中难表达或表现较少,不育系对所配组合的米质特征起到了决定性作用。本研究还表明,根据优质米对7项米质指标的要求来看,9个不育系中川谷A、中浙A和宜香1A所配组合多数能达到优质米标准,是选育优质杂交水稻的理想不育系。

几个优良籼稻亲本品质性状的配合力和杂种优势分析

以3个不育系和10个恢复系为材料,采用NCII交配设计研究10个米质性状的配合力和杂种优势。结果表明:①大多数品质性状的量值介于双亲之间,除粒重表现一定的超亲优势、垩白度和粒宽表现一定的正向平均优势外,其他品质性状优势不明显。②杂种稻米的品质性状主要受不育系或恢复系的影响,其中粒长、粒宽和直链淀粉含量3个性状,不育系的影响要高于恢复系;而对于整精米率、粒重、垩白率、垩白度和糊化温度,则恢复系的影响要高于不育系。③就优质育种的利用价值而言,不育系以广占634S为好,恢复系以扬稻6号为好,R527、镇恢084次之,用上述亲本选配的杂交组合米质较好;恢复系特青、盐恢559表现为一般配合力效应低,特殊配合力方差小,优质育种利用价值不大。