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 from Southeast Asia

Totaling 662 rice germplasms were collected from Southeast Asia,including 120 wild species and 542 cultivated rice plants.An information database of the collections was constructed after phenotype identification.Based on evaluation of cultivated rice,some germplasm resources were found to have good characteristics,including 58 accessions resistant to brown planthopper,nine accessions resistant to rice blast,eleven accessions resistant to bacterial blight,and twelve accessions with salt-tolerance.The introduced rice resources broaden genetic basis of rice and enrich rice genbank in China,which would play an active role in rice genetic research and rice breeding.

Screening of Drought Stress Indicators and Analysis of Drought Resistance in Cultivated Rice Germplasm Resources in Guangxi

This study aimed to screen drought stress indicators and analyze the drought resistance in 105 cultivated rice germplasm resources in Guangxi Zhuang Autonomous Region under drought stress in the whole growth period based on D value of seven morphological traits including panicle neck thickness,effective panicle number per plant,1 000-grain weight,filled grain number per panicle,total grain number,seed setting rate and yield per plant.According to the results,under drought stress,yield per plant exhibited significant positive correlation with panicle neck thickness and exhibited extremely significant positive correlation with other five morphological traits.Based on the identification and evaluation of comprehensive drought-resistance index D value,seven highly drought-resistant cultivated rice varieties were screened,accounting for 6.67％.Upland rice germplasm resources in Guangxi Zhuang Autonomous Region possess strong drought-resistance capacity,which could be used to screen highly drought-resistant rice germplasm materials.This study provided material basis and theoretical reference for breeding drought resistant rice cultivars in Guangxi Zhuang Autonomous Region.

Track Monitoring on Viability of Rice Germplasm Resources and Regeneration under Low Temperature Storage

53 rice germplasm resources warehoused during 1981-1984 were regarded as materials to monitor the viability at warehouse time and different years after warehoused. The results showed that seed germination rates of different rice germplasm resources assumed descending trend in storage, with annual decreasing rate between 0.12%-3.05% ; the seed germination rates of most cultivars were above 75% after stored for 26 years; forecasting analysis based on the germination rate of 75% as reference showed a huge difference of safe storage life for different rice germplasm resources, ranging from 12 to 50 years, even longer time. The results suggest that track monitoring on viability and regeneration of rice cultivars is of great importance for germplasm resources conservation.

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.

A Comprehensive Evaluation on Blast-resistant Rice Germplasm Resources in Guizhou Province

Under the condition of natural infection, 60 blast-resistant rice germplasm resources were screened from the blast nursery through many years of natural identifcation, which would provide abundant parent materials for rice blast resistance breeding. The disease level of panicle blast was above grade seven in most of the core materials, including 15 of R grade, 23 of MR grade, 14 of MS grade, 7 of S grade and 1 of HS grade. The results of cross test showed in the F1 generation, 12 rice germplasm resources performed well; and the seed-setting percentages of 17 rice germplasm resources were higher than 50%, and those of 10 were below 5%.

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）.

我国水稻种质资源创新研究与利用进展

农业种质资源主要包括农作物、畜禽、农业微生物和药用植物等种质资源。截止到2023年,我国保存的作物种质资源有超过54万份,其中有8万多份是水稻种质资源,如何对这么庞大的水稻种质资源进行精确评价与利用,这将对今后水稻种质创新与育种具有重要意义。本文梳理了我国水稻种质资源收集、评价与精确鉴定、水稻新品系创制、水稻杂种优势利用、水稻种质创制新技术、新方法以及水稻优异基因资源的挖掘与利用等方面的进展,并归纳形成了水稻种质资源创制与利用的新模式。最后,本文就当前水稻核心种质构建、种质资源鉴定与挖掘以及种质资源共享共赢机制等方面的问题进行了探讨,并就如何加强专用型核心种资的构建、种质资源的精确鉴定、种质资源的创新研究、种质资源的共享机制以及种质资源的合作交流进行了分析与展望,以期为进一步深入开展水稻种质资源鉴定评价与创新利用提供一定的参考和帮助。

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。

粤稻百年主要水稻科技创新成就概述

回顾和简要概述了广东省农业科学院水稻研究所百余年来在稻作科学方面取得的主要成就。在稻种资源方面,作为最早开展稻种资源研究的单位,已收集保存栽培稻和野生稻资源24000多份,鉴评筛选出外选35等大批优异种质,创制出稻瘟病持久抗性、优质的育种亲本三黄占2号、28占和香丝苗126等广泛应用于新品种培育。在水稻育种方面,开创了栽培稻与野生稻杂交育种先河;通过人工杂交育成最早在生产上大面积应用的籼稻矮秆品种广场矮,从而开辟了水稻矮化育种新途径,进而培育出珍珠矮、广陆矮4号、桂朝2号、双桂36、特青等大品种,为农业史上的第一次绿色革命发挥了重要推动作用;作为最早开展籼型优质稻育种单位,先后育成了双竹占、黄华占、粤农丝苗、美香占2号、泰丰优208等大面积种植的优质新品种;在杂交稻育种方面,创制出野败型、红莲型高配合力、高异交率和细长粒型优质三系不育系天丰A、五丰A、荣丰A、丛广41A、粤泰A、粤丰A、泰丰A和广8A等,创制出感温与感光型恢复系广恢3550、广恢998、广恢122等,广泛应用于杂交稻育种与生产;主持和合作育成累计推广面积超千万亩的水稻品种(组合)45个。在水稻栽培方面,从20世纪50—60年代农民水稻高产经验——“潮汕经验”的总结,到80年代的水稻高产栽培技术规程研究、90年代的水稻抛秧技术和21世纪的水稻“三控”施肥技术等,这些栽培技术的研发,实现了广东省水稻生产良种良法配套,为水稻高产稳产和国家粮食安全发挥了极其重要的作用。