Synthetical Evaluation on the Qualitative and Quantitative Resistance of Rice Germplasms to Magnaporthe oryzae

[Objectives]This study was conducted to screen out rice resources resistant to rice blast(Magnaporthe oryzae).[Methods]The qualitative and quantitative resistance of 1659 rice resources from 45 countries and regions to rice blast were evaluated by disease nursery in upland condition and the test of the spectrum to rice blast isolates.[Results]There were 292 entries which accounted for 17.6%showed high blast resistance(0 and 1 disease scale),68 entries(counted for 4.1%)showed resistance to blast(3 disease scale);and the number of the entries showed intermediate resistance,intermediate susceptible and susceptible were 208(with the corresponding percentage of 12.5%),471(28.4%),620(37.4%)respectively.Among the tested entries,27 entries including BG1222,BL122,BTX,IR37704-131-2-3-2,and LEBONNET had showed broad-spectrum blast resistance with the resistance frequency of higher than 90%,Quantitative resistance evaluation was conducted on some key resources,and 14 entries,of which are BR27,DRAGO,IR100,QINLIUAI、SERIBU GANTANG,YUEXIANGZHAN and so on,showed good quantitative resistances,and 8 entries had higher quantitative resistances than IR36.[Conclusions]This study provides important blast resistance resources for the local rice breeding program and has a significant value for the discovery of new blast resistance genes and its application in the blast resistance breeding.

Evaluation of Rice Germplasm for Resistance to the Small Brown Planthopper (Laodelphax striatellus) and Analysis of Resistance Mechanism

One hundred and thirty-eight rice accessions were screened for resistance to the small brown planthopper （SBPH） （Laodelphax striatellus Fallen） by the modified seedbox screening test. Twenty-five rice accessions with different levels of resistance to SBPH were detected, accounting for 18.1% of the total accessions, which included 2 highly resistant, 9 resistant and 14 moderately resistant varieties. Compared with indica rice, japonica rice was more susceptible to SBPH. Antixenosis test, antibiosis test and correlation analysis were performed to elucidate the resistance mechanism. The resistant check Rathu Heenati （RHT）, highly resistant varieties Mudgo and Kasalath, and resistant variety IR36 expressed strong antixenosis and antibiosis against SBPH, indicating the close relationship between resistance level and these two resistance mechanisms in the four rice varieties. Antibiosis was the dominant resistance pattern in the resistant varieties Daorenqiao and Yangmaogu due to their high antibiosis but low antixenosis. Dular, ASD7 and Milyang 23 had relatively strong antixenosis and antibiosis, indicating the two resistance mechanisms were significant in these three varieties. The resistant DV85 expressed relatively high level of antixenosis but low antibiosis, whereas Zhaiyeqing 8 and Guiyigu conferred only moderate antibiosis and antixenosis to SBPH, suggesting tolerance in these three varieties. Antibiosis and antixenosis governed the resistance to SBPH in the moderately resistant accession 9311. Antixenosis was the main resistance type in V20A. Tolerance was considered to be an important resistance mechanism in Minghui 63 and Yangjing 9538 due to their poor antibiosis and antixenosis resistance. The above accessions with strong antibiosis or antixenosis were the ideal materials for the resistance breeding.

Analysis of the Relationship between Blast Resistance Genes and Disease Resistance of Rice Germplasm via Functional Molecular Markers

Rice blast disease is one of the most devastating diseases of rice(Oryza sativa L.)caused by the fungus Magnaporthe oryzae(M.oryzae),and neck blast is the most destructive phase of this illness.The underlying molecular mechanisms of rice blast resistance are not well known.Thus,we collected 150 rice varieties from different ecotypes in China and assessed the rice blast resistances under the natural conditions that favoured disease development in Jining,Shandong Province,China in 2017.Results showed that 92(61.3%)and 58(38.7%)rice varieties were resistant and susceptible to M.oryzae,respectively.Among the 150 rice varieties screened for the presence of 13 major blast resistance(R)genes against M.oryzae by using functional markers,147 contained one to eight R genes.The relationship between R genes and disease response was discussed by analysing the phenotype and genotype of functional markers.The results showed that the rice blast resistance gene Pita was significantly correlated with rice blast resistance.Our results provided a basis for the further understanding of the distribution of 13 major R genes of rice blast in the germplasm resources of the tested rice varieties,and were meaningful for rice disease resistance breeding.

Yuanyou 1R—a new rice germplasm material

A new rice germplasm material Yuanyou 1R was developed in Changsha Institute of Agricultural Modernization, Academia Sinica, Hunan Province, China. New hybrid rice combinations could be developed by utilizing this new germplasm material. In this way, a new hybrid rice Changyou 88 has been developed by Prof LI Damo and his colleagues of this Institute. Changyou 88 shows very strong heterosis good

Introduction and Utilization of INGER Rice Germplasm in China

The International Network for Genetic Evaluation of Rice (INGER) is a global partnershipbetween international and national agricultural research institutions. INGER focuses onworldwide exchange, evaluation and utilization of improved varieties and elite breedinglines of rice. China has actively participated in the activities of INGER since 1980.During the pasted years, 26500 INGER entries with diversity genetic background have beenintroduced and evaluated by Chinese scientists. Among of them, 37 commercial varietiesdirectly from elite INGER entries and 27 rice hybrids using INGER lines as their restorerlines/donors have been released to farmers in China. About 1900 INGER entries wereindirectly utilized as cross parents or pest resistant donors in various national andprovincial rice breeding programs. Based on the incomplete statistics, there were 14.5million cumulated hectares planting these varieties and hybrids, from which 5.44 MT ofincreased rough rice has been received by farmers. INGER accelerates the transfer ofadapted varieties and hybrids to farmers, and increases the diversity of rice germplasmin cultivation. Therefore, INGER cooperation has made great benefit both in economy andsociety in China.

Screening for Rice Germplasms with Specially-Elongated Mesocotyl

The lengths of mesocotyl in the seedlings of 84 lowland rice varieties and 12 upland rice varieties were measured following the treatments of daylight and darkness during germination. The elongation of mesocotyl in the varieties tested was inhibited under daylight condition, and the mesocotyl of all the varieties elongated variably under darkness condition. The elongated lengths of the mesocotyl in upland rice, ranging from 0.36 cm to 1,61 cm with an average of 0.81 cm, was obviously longer than those in lowland rice, ranging from 0.12 cm to 1.56 cm with an average of 0.42 cm. Among 14 rice varieties with over 1 cm of mesocotyl length, five belonged to upland rice, and nine to lowland rice. The possible utilization of the elongated-mesocotyl rice germplasm in varietal imorovement, direct-seeded plantina and seed ouritv testina were discussed.

Identification of Cold Tolerance of Rice Germplasm Resource at Germinating Stage in Cold Region

Total 75 rice varieties （lines） in Heilongjiang Province （or cold region） as germplasm resources were identified for cold tolerance at germinating stage by controlling temperature in artificial incubator. The results showed that the shooting seed rate at the germinating stage could be used as the evaluation index of cold tolerance. The cold tolerance was recorded on 1-9 scale and could be identified by the criteria of five indexes such as highly tolerant （HT）, tolerant （T）, moderately tolerant （MT）, susceptible （S）, highly susceptible （HS）.

Evaluation and Genetic Classification of Rice Germplasm Resources Resistant to Rice Blast

[ Objective] This study aimed to explore rice germplasm resources resistant to rice blast and provide theoretical basis for the modification of rice blast- resistant germplasm resources. [ Method] The resistance of 120 rice materials to rice blast was identified at three experimental areas. [ Result] The resistance of 120 experimental materials was at grade 0 -9 to panicle blast in Hainan Province, at grade 0 -9 to seedling blast in Fujian Province and at grade 3 -9 topanicle blast in Guangxi Zhuang Autonomous Region. Analysis of correlations between agronomic traits and rice blast resistance indicated that the resistance of experimental materials could not be simply determined based on agronomic traits. Furthermore, 61 published SSR makers closely linked to rice blast were selected and synthe- sized for genotypic analysis of 120 experimental materials. The results of cluster analysis preliminarily divided 120 germplasms into resistant varieties and susceptible varieties. [ Conclusion] These rice germplasm resources are of important value for breeding new materials resistant to rice blast.

Innovation on Distant Hybridization of Saline-tolerant Mud Flat Spartina and Rice Germplasm

To explore saline-tolerant high yield Spartina and rice germplasm resources,innovate upon distant hybridization technology,and develop new saline-tolerant mud flat Spartina germplasm,autonomous patent for invention was used to study distant hybridization of Spartina and rice in 2005- 2016. The study adopted tidal flat planting screening,phenotypic screening,molecular marker assisted selection,to find biological evidences of new germplasm,and also applied crossbreeding,conventional breeding,and molecular breeding,to select new saline-tolerant Spartina and rice varieties. With 12 years of efforts,the team developed 1498 crossbreeding combinations and established pedigree file and seed bank,tested 307 crossbreeding materials(57 hybrid seeds showed parental genetic components of Spartina and Rice); obtained Spartina/ Rice distant hybridization and seed setting,transplanting,hybridization material economic traits,and molecular biological experimental evidences; Rice♀× Spartina ♂ hybridization success rate of 1. 04- 1. 39%; obtained authorization of patent for invention of Distant Hybridization Methods for Spartina and Rice; formulated procedures for high yield cultivation of Spartina-Rice,planted 33. 33 hm2Spartina-Rice in coastal saline and alkaline land,cultivated 10 new saline-tolerant Spartina-Rice varieties,and the rice yield up to 5. 925- 8. 28 t / hm2. Results indicate that Spartina-Rice is saline-tolerant high yield rice germplasm,developed through sexual hybridization,conventional breeding,and molecular breeding technologies,and is optimal crop for saline and alkaline land. Success of Spartina-Rice solves the problem of saline-tolerant crop badly for transformation of saline and alkaline land,the problem of feeds for herbivores,as well as problem of environmental pollution resulted from straw burning. Besides,it is of essential scientific significance for resource utilization,increase of agricultural efficiency,grain security,and farmland strategy,so it has broad application prospect.

An Analysis on the Heat Resistance of Rice Germplasm Resources during Flowering Period

56 Chinese rice core germplasm resources,18 foreign rice germplasm resources and 6 restorer lines are subjected to high temperature stress during flowering period. Based on relative spikelet fertility rate,rice heat resistance is evaluated. The results show that different resistance to high temperature exists in different varieties,and 6 new rice varieties present high heat resistance.

Genomic prediction using composite training sets is an effective method for exploiting germplasm conserved in rice gene banks

Germplasm conserved in gene banks is underutilized,owing mainly to the cost of characterization.Genomic prediction can be applied to predict the genetic merit of germplasm.Germplasm utilization could be greatly accelerated if prediction accuracy were sufficiently high with a training population of practical size.Large-scale resequencing projects in rice have generated high quality genome-wide variation information for many diverse accessions,making it possible to investigate the potential of genomic prediction in rice germplasm management and exploitation.We phenotyped six traits in nearly 2000 indica(XI)and japonica(GJ)accessions from the Rice 3K project and investigated different scenarios for forming training populations.A composite core training set was considered in two levels which targets used for prediction of subpopulations within subspecies or prediction across subspecies.Composite training sets incorporating 400 or 200 accessions from either subpopulation of XI or GJ showed satisfactory prediction accuracy.A composite training set of 600 XI and GJ accessions showed sufficiently high prediction accuracy for both XI and GJ subspecies.Comparable or even higher prediction accuracy was observed for the composite training set than for the corresponding homogeneous training sets comprising accessions only of specific subpopulations of XI or GJ(within-subspecies level)or pure XI or GJ accessions(across-subspecies level)that were included in the composite training set.Validation using an independent population of 281 rice cultivars supported the predictive ability of the composite training set.Reliability,which reflects the robustness of a training set,was markedly higher for the composite training set than for the corresponding homogeneous training sets.A core training set formed from diverse accessions could accurately predict the genetic merit of rice germplasm.

Natural Variation in the Sequence of SNAC1 and Its Expression Level Polymorphism in Rice Germplasms under Drought Stress

Water is a major limiting factor for food production and many countries fail to produce sufficient food for their population due to severe water scarcity （Jury and Vaux, 2005）. Rice is the main staple food worldwide. More than 50% of rice in the world is rain-fed and drought causes severe reduction in rice grain yield in rain-fed environments （Venuprasad et al., 2007; Zhang, 2007; Sandhu et al., 2014）. Therefore, enhancing drought resistance （DR） of rice is important for food security. However, DR is a complex trait, which is controlled by a large number of loci with small effect and is also affected by different genetic background, genotype-by-environment interaction and other stresses such as heat （Hu and Xiong, 2014）.

A New-Nipponbare Rice Germplasm with High Seed-Setting Rate

Rice （Oryza sativa L.） is an important crop providing staple food for more than half the world＇s population and also considered as a model plant for molecular biological study of the cereals. In 1998, the large-scale sequencing of japonica rice cultivar Nipponbare （bred at Aichi Agricultural Center in Japan and released in 1963） was initiated by International Rice Genome Sequencing Project （IRGSP） and the high-quality draft of genome was announced in 2002 （Goff et al,, 2002）. Owing to its easy genetic transformation and released whole genome sequencing data, Nipponbare is widely used in functional genomic research （Piffanelli et al., 2007; Luan et al., 2008; Hu et al., 2010; Thang et al., 2010; Tabuchi et al., 2011; Zhang et al., 2011; Jiang et al., 2012; Lu et al.. 2013）.

华南双季直播稻耐淹成苗率种质筛选及比较分析

本研究旨在鉴定在华南稻区不同季节下适宜直播的水稻种质材料,以适应该地区自然条件并支持新品种培育。选取华南地区广泛使用的水稻品种及其亲本作为试验对象,分别在早季与晚季进行了大田直播淹水成苗实验(水深6 cm)。结果表明,早季直播淹水成苗率均极显著地高于晚季,且早、晚季的淹水成苗率间相关不显著(R^(2)=-0.1253)。在早季条件下,‘Francis’、‘starbonett99’、‘润丰B’、‘Kasalath’和‘粤抗1614’等5个材料展现出较高的淹水成苗率(65.0%~76.5%),并且聚类分析将这5份材料都同聚在类群I;而在晚季条件下,‘玉晶软占’和‘常规稻5’的淹水成苗率最高,分别仅为42.5%和39.5%,同样被聚在类群I。这一结果说明由于华南稻区早晚季气候特征差异,选育直播稻新品种时应考虑选择适合各自季节的淹水成苗率高的种质材料。

水稻种质资源农艺性状评价和基因型鉴定

为了提高苏州地区水稻育种的效率和水平,对18份常熟市农业科学研究所引进和改良的种质资源进行了重要农艺性状和遗传基础鉴定分析.结果显示18份水稻种质资源基本为偏短粒型,且粒型、粒重、出糙率和精米率相近.除镇稻6914和常粳22-4外,其余种质材料的结实率基本在90%以上.其中8份种质材料含有香型基因Badh2,结合直链淀粉含量分析结果,武香粳5245、南粳46和常香粳1813属于香软米,荃香糯3号和银香38是香糯米,常粳20-13和宁香粳11号为香粳米.对这些水稻种质材料的稻瘟病抗性基因分析结果显示,除嘉58和南粳46未检测到抗性基因外,其余种质材料基本含有2个以上抗性基因,其中常香粳1813含有Pid2和Pid3,常粳22-4含有Pita、Pid2、Pid3、Pita2和Pik1-Pik2抗性基因,稻瘟病菌接种试验显示抗病水平较好.本研究为种质资源的综合分析评价提供了新思路,也为适合江南地区优良水稻种质的选育和引进提供数据支撑.

水稻抗白叶枯病种质资源筛选及抗性基因鉴定

【目的】筛选抗水稻白叶枯病Ⅴ和Ⅸ型菌的水稻品种。【方法】以97个收集自热带亚热带地区的抗褐飞虱水稻品种为待测样品,水稻白叶枯病Ⅴ、Ⅸ型菌为菌种。用剪叶接种法鉴定水稻在苗期和成株期的抗白叶枯病能力并划分抗性等级。对抗性表现优异的品种构建定位群体,并进行基因定位及克隆。【结果】筛选出苗期抗Ⅴ型菌的水稻品种20个,成株期8个,2个时期均表现为中抗及以上的品种4个;苗期抗Ⅸ型菌的水稻品种34个,成株期9个,2个时期均表现为中抗及以上的品种1个。其中,供试水稻品种‘BX02’在2个时期对Ⅴ型菌株抗性表现极佳。‘BX02’与‘9311’杂交构建的F2遗传群体,抗性位点被定位在5号染色体,极大似然函数值达到40.6,该区间包含已克隆的水稻抗白叶枯病Ⅴ型菌xa5基因,序列扩增分析验证为白叶枯抗性基因xa5。【结论】筛选出在2个时期均抗白叶枯病Ⅴ型菌的水稻品种4个,抗Ⅸ型的水稻品种1个,为水稻抗白叶枯种质资源筛选提供了基础材料。

水稻拟禾本科根结线虫的发生及抗性基础

水稻是世界主要栽培作物之一,也是世界众多人口的主要食物,但根结线虫病危害给水稻种植带来严重挑战。其中,拟禾本科根结线虫(Meloidogynegraminicola,Mg)是引起水稻根结线虫病的重要线虫病原之一,广泛分布于亚洲、美洲和南非等主要稻田种植区,成为制约水稻安全生产的重要生物因素。此外,在全球气候变暖趋势下,Mg种群结构呈由南向北扩展的趋势。本文综述了Mg在世界范围内的发生、分布、致病机理、抗病种质资源及抗性基因鉴定和当前的防控措施。探讨了未来气候变暖可能影响Mg的发生与分布,今后加强我国稻田Mg发病实时监测对于该病害的绿色防控极为重要。充分利用全基因组测序等技术手段深入挖掘新Mg抗性水稻资源、鉴定新抗性QTL/基因以及培育持久抗性的新品种是未来开展Mg绿色防控的主流方向;同时,探索Mg综合防控策略,将抗性水稻种质资源、生物防控技术和稻田栽培措施等进行组合运用,有助于进一步提高水稻线虫病害的防控效果,以保障我国水稻产业的安全生产。

基于表型性状构建禾初级核心种质

“禾”是适应贵州黔东南山区峡谷森林中遮荫、泥沼、寒冷、积水等特殊自然生境生长的地方水稻品种。以402份禾种质资源为材料,依据禾颖尖颜色差异将原始种质划分为5组,基于26个表型性状,采用逐步聚类法以6种总体取样规模、4种组内取样比例和2种组内取样方法筛选最佳取样策略,构建禾初级核心种质,并对其进行综合评价。结果表明,10%为最适总体取样规模,组内取样比例法以对数比例法最优,聚类取样法是组内最佳取样方法。在最佳取样策略下,共获得47份禾初级核心种质,占比11.69%,表型保留比例为95.77%。核心种质评价结果表明,构建的核心种质作为原始种质的浓缩能够代表禾原始种质的遗传多样性。

基于SNP芯片的贵州香禾糯遗传多样性分析及核心种质构建

以317份贵州香禾糯种质资源为试验材料,10份籼稻材料为对照,采用1 K mGPS SNP芯片对供试材料的遗传多样性和遗传结构进行分析,在此基础上构建贵州香禾糯核心种质并进行评价。结果表明,1 K mGPS SNP芯片在317份香禾糯材料中共获得731个良好多态性SNP位点,多态性标记比例为17.89%,最小等位基因频率为0.0505~0.5000,观测杂合度为0~0.6940,期望杂合度为0.0959~0.5000,多态性信息含量为0.0913~0.5736。基于IBS遗传距离的NJ聚类分析将327份水稻材料分为籼、粳两个亚群,其中317份贵州香禾糯划分为粳稻亚群。利用Core Hunter 3对香禾糯原种质设置5%、10%、15%、20%、25%、30%等6种抽样比例,遗传多样性参数的t检验表明,15%的抽样比例即可保持遗传多样性参数的最大化,同时剔除了许多冗余材料,最终确定47份香禾糯资源为构建的核心种质。

长江上游国家水稻区试品种耐热性鉴定与评价

本研究旨在评估全球气候变暖对水稻生产的影响,并鉴定长江上游地区水稻品种的开花期耐热性。我们对2020—2022年476份国家长江上游水稻品种的开花期进行了大田自然高温和温室高温两种环境下的耐热性测试与评价。结果表明,参试品种整体表现出良好的开花期耐热性,其中分别有67、324、49、30和6份品种被划分为强(1级)、较强(3级)、一般(5级)、较弱(7级)和弱(9级)耐热性类别,占比分别为14.1%、68.1%、10.3%、6.3%和1.3%。通过年份对比发现,耐热性在不同年份的整体表现为:2021年优于2020年,而2020年又优于2022年。从品种类型来看,两系杂交稻的耐热性优于三系杂交稻,而三系杂交稻又优于常规稻。不同试验渠道来源的品种在耐热性上呈现出绿色通道试验优于国家统一试验,国家统一试验又优于联合体试验的趋势。本试验中鉴定出的耐热性强或较强的391份品种,在保证产量、品质及抗病性等其他重要农艺性状的前提下,可在长江上游热害常发区作为耐热品种优先推广种植;对于耐热性一般的49份品种,建议在审定推广时明确适宜种植区域,避免在热害常发区种植。至于耐热性较弱或弱的36份品种,建议在审定时要特别谨慎。