Identification of Quantitative Trait Loci for Grain Appearance and Milling Quality Using a Doubled-Haploid Rice Population

Improving grain quality, which is composed primarily of the appearance of the grain and its cooking and milling attributes, is a major objective of many rice-producing areas in China. In the present study, we conducted a marker-based genetic analysis of the appearance and milling quality of rice （Oryza sativa L.） grains using a doubled-haploid population derived from a cross between the indica inbred Zhenshan 97 strain and the japonica inbred Wuyujing 2 strain. Quantitative trait locus （QTL） analysis using a mixed linear model approach revealed that the traits investigated were affected by one to seven QTLs that individually explained 4.0%-30.7% of the phenotypic variation. Cumulatively, the QTL for each trait explained from 12.9% to 61.4% of the phenotypic variation. Some QTLs tended to have a pleiotropic or location-linked association as a cause of the observed phenotypic correlations between different traits. Improvement of the characteristics of grain appearance and grain weight, as well as an improvement in the milling quality of rice grains, would be expected by a recombination of different QTLs using marker-assisted selection.     

水稻高温热害的研究现状与进展

全球气候变暖环境下,水稻高温热害频发,孕穗-开花期和灌浆期高温已成为制约水稻产量和品质的主要因素之一。本文综述了水稻高温热害的发生特点(鉴定与分级、区域和时间)和高温对水稻生长发育(生理、产量和品质)的影响,总结了水稻高温热害的数量性状座位定位、转录组和蛋白质组分析等分子生物学研究及监测预警与风险评估,重点阐述了高温热害的防御措施,包括选用耐热品种、改善田间管理和喷施外源物质,并对今后水稻高温热害研究进行了展望,以期为水稻高温热害防御和农业减灾增效提供科学支持。     

Identification of quantitative trait loci for grain quality in an advanced backcross population derived from the<Emphasis Type="Italic"> Oryza sativa</Emphasis> variety IR64 and the wild relative<Emphasis Type="Italic"> O. rufipogon</Emphasis>

The objective of this study was to identify quantitative trait loci (QTLs) associated with grain quality in rice. Two hundred eighty-five BC₂F₂ families developed from an interspecific cross between cv IR64 and Oryza rufipogon (IRGC 105491) were evaluated for 14 seed quality traits. A total of 165 markers consisting of 131 single sequence repeats and 34 restriction fragment length polymorphism markers were used to create a genetic linkage map spanning the 12 rice chromosomes. Twenty-three independent QTLs were identified using single point analysis, interval mapping, and composite interval mapping. These loci consisted of one QTL for filled rough/total rough rice ratio, two for grain density, one for percentage of de-husked rice grains, two for percentage of green rice grains, three for percentage of damaged-yellow rice grains, two for percentage of red rice grains, one for milled rice recovery, three for head rice recovery, four for broken rice grains, two for crushed rice grains, one for amylose content, and one for gel consistency. For most of the QTLs identified in this study, the O. rufipogon-derived allele contributed an undesirable effect. For amylose content and gel consistency, the O. rufipogon allele may be useful in an IR64 background, depending on the cultural preferences of the consumer. Careful selection against the regions associated with negative effects will be required to avoid unwanted grain quality characteristics during the development of improved varieties for yield and yield components using introgressions from O. rufipogon.Communicated by D. Mackill     

Genetic bases of appearance quality of rice grains in Shanyou 63, an elite rice hybrid

Appearance quality of the rice grain represents a major problem of rice production in many rice-producing areas of the world, especially in hybrid rice production in China. In this study, we conducted a molecular marker-based genetic analysis of the traits that are determinants of the appearance quality of rice grains, including traits specifying grain shape and endosperm opacity. The materials used in the analysis included an F_2:3 population and an F₁₀ recombinant inbred line population from a cross between the parents of Shanyou 63, the most widely grown rice hybrid in China. Molecular marker-based QTL (quantitative trait locus) analyses revealed that grain length and grain width were each controlled by a major QTL accounting for a very large proportion of the genetic variation, plus one or two minor QTLs each explaining a small proportion of the genetic variation. The major QTLs can be detected in both the F_2:3 and recombinant inbred line population using both paddy rice and brown rice, whereas the minor QTLs were detected only occasionally. The QTL located in the interval of RG393-C1087 on chromosome 3 is the major locus for grain length, and the one in the interval RG360-C734a on chromosome 5 plays a major role in determining grain width. Similarly, white belly, which largely determines the opacity of the endosperm, is almost entirely controlled by a major locus on chromosome 5, located in the same genomic region as the major QTL for grain width. The implications of the results with respect to hybrid rice improvement were discussed. Received: 20 February 2000 / Accepted: 21 March 2000     

二氧化碳浓度增高对稻、麦品质影响研究进展

作物品质的形成是品种遗传特性和环境条件综合作用的结果.一般认为大气中CO₂浓度增高将对作物品质产生重要影响.本文分别从蛋白质与氮含量、微量元素以及其他品质性状等3个方面综述了国内外关于CO₂浓度增高对水稻、小麦品质影响的研究进展,强调了该领域研究的必要性和紧迫性,并提出了研究的重点内容及主要方向.主要包括：大气中CO₂浓度增高对水稻、小麦品质的直接影响及品种间的差异;大气中CO₂浓度增高及其与其它气候因子协同作用对水稻、小麦品质的综合影响及其指标量化;大气中CO₂浓度增高及气候变化对水稻、小麦品质形成过程的影响机理;适应CO₂浓度增高的水稻、小麦品质改良育种的方向与策略;适应CO₂浓度增高的水稻、小麦品质改良的综合生产技术体系和分子标记及转基因技术在水稻、小麦品质改良育种方面的应用.     

杂交水稻加工、外观品质性状间接选择的数学模型研究

利用19个优质杂交水稻品种（组合）,采用双向逐步筛选,求出加工和外观品质性状与产量性状的最优相关子集,建立了品质性状的回归方程,并对子集作了广义相关分析。结果表明千粒重、穗长与糙米率、整精米率、垩白粒率的相关已反映了品质性状与产量性状相关的主要信息（90％以上）,千粒重在21.96～27.64g、穗长在21.18～26.07cm范围内,增大千粒重可提高糙米率,但整米率下降、垩白粒率上升,适当缩短穗长可提高糙米率和整精米率,降低垩白粒率。     

灌溉方式对黄淮稻区优质粳米品质的影响

为探明不同水深处理对优质稻米的影响,研究了湿润、浅水、深水3种灌溉方式对优质粳稻(圣稻14、圣稻2572、圣稻18)籽粒外观、稻米直链淀粉、蛋白质含量及淀粉RVA谱的影响,分析了稻米品质与理化指标之间的关系.结果表明: 浅水灌溉下籽粒面积、周长、粒长、稻米蛋白质含量显著高于其他灌溉方式,垩白率和垩白度的表现相反;RVA谱的最高黏度和热浆黏度值以湿润灌溉最高,深水灌溉最低,最终黏度值以深水灌溉最低;不同品种RVA谱的崩解值、消减值、回复值及稻米直链淀粉含量对3种灌溉方式的响应存在明显的基因型差异.圣稻14以湿润灌溉的食味品质最好,圣稻18则以深水灌溉最好.相关分析表明,稻米RVA谱特征值与稻米外观指标及蛋白质含量之间存在显著的相关性.回归与通径分析表明,粒型是影响崩解值与消减值的主要因子,而稻米蛋白质与直链淀粉含量是影响回复值的主要因子.     

The dynamic gene expression from different genetic systems for protein and lysine contents of indica rice

The dynamic expression of genes for protein and lysine contents of rice grain under different environments was carried out with time-dependent measures by using the developmental genetic models for quantitative traits of triploid endosperm in cereal crops. The results showed that the genetic effects, especially genotype × environment (GE) interaction effects from the genes expression of different genetic systems including triploid endosperm, cytoplasm and diploid maternal plant were important for the performance of both nutrient quality traits at all developmental times/stages of rice grain. The conditional genetic variance analysis found that the activation of quantitative genes especially from endosperm and maternal plant genetic systems for protein and lysine contents was gradually carried through the developmental process of rice grain. The net genetic effects showed that the new expression of quantitative genes for protein and lysine contents was more active at late filling stage (15–21 days after flowering) and maturity stage (22–28 days) of rice grain. Also the sequential expression of cytoplasmic genes cannot be ignorable for the development of nutrient quality traits. The phenomena that some genes could continuously express for several developmental stages or the genes expression could be interrupted among developmental stages of rice grain was detected especially for net endosperm additive main effects or maternal additive main effects. The differences of genetic relationships from different genetic systems were found for protein and lysine contents among developmental times of rice grain.     

灌浆期气象因子对杂交中籼稻米碾米品质和外观品质的影响

 以`II优7号'和`4228A/江恢15'两个杂交中稻组合为材料,通过分期播种处理,研究了灌浆期气象因子与杂交中稻稻米碾米品质和外观品质的关系。结果表明：在稻谷碾米品质和外观品质的5项指标中,显著受灌浆期气象因子影响的有整精米率、垩白粒率和垩白度3项指标,显著影响这3项指标的是齐穗后0～20 d 6个气象因子中的相对湿度、日均气温、日最低气温3个,齐穗后21～30 d的气象因子对米质的影响不显著。从总体上看, 齐穗后0～20 d的日均气温和日最低气温低, 相对湿度大,有利于提高整精米率,降低垩白粒率和垩白     

Diversity of Global Rice Markets and the Science Required for Consumer-Targeted Rice Breeding

With the ever-increasing global demand for high quality rice in both local production regions and with Western consumers, we have a strong desire to understand better the importance of the different traits that make up the quality of the rice grain and obtain a full picture of rice quality demographics. Rice is by no means a ‘one size fits all’ crop. Regional preferences are not only striking, they drive the market and hence are of major economic importance in any rice breeding / improvement strategy. In this analysis, we have engaged local experts across the world to perform a full assessment of all the major rice quality trait characteristics and importantly, to determine how these are combined in the most preferred varieties for each of their regions. Physical as well as biochemical characteristics have been monitored and this has resulted in the identification of no less than 18 quality trait combinations. This complexity immediately reveals the extent of the specificity of consumer preference. Nevertheless, further assessment of these combinations at the variety level reveals that several groups still comprise varieties which consumers can readily identify as being different. This emphasises the shortcomings in the current tools we have available to assess rice quality and raises the issue of how we might correct for this in the future. Only with additional tools and research will we be able to define directed strategies for rice breeding which are able to combine important agronomic features with the demands of local consumers for specific quality attributes and hence, design new, improved crop varieties which will be awarded success in the global market.     

空间诱变水稻大粒型突变体的遗传育种研究

对粳稻农垦58经空间诱变产生的大粒型突变体进行大粒型性状的遗传分析和育种应用研究。结果表明,大籽型突变体的籽粒大小（以籽粒体积表示）表现为受多基因控制的数量性状。大粒型突变体谷粒细长,具馨香味,外观品质优,对粳稻的亲和性好,是一个罕见的优质米资源。以大粒型突变体为供体,高产、外观米质差的晚粳推广品种为受体,采用不饱和回交结合分离世代糙米外观品质鉴定的方法,将大粒型突变体的优质性状导入晚粳背景,选育出外观米质优的晚粳新品系。对采用不饱和回方法改良数量性状进行了讨论。     

水稻粒形性状的遗传及相关基因定位与克隆研究进展

作物育种的首要目标是提高产量。水稻粒形是与水稻产量性状直接相关,与品质性状存在着密切关系的数量性状,其评价指标主要是粒长、粒宽、粒厚、长/宽和长/厚。近年来,水稻粒形的数量遗传研究取得了重要进展,并成功定位克隆了一批控制水稻粒形的基因。文章综述了水稻粒形的经典遗传研究、QTL定位、粒形基因的克隆和功能分析以及在水稻超高产育种中的利用。     

Genetic studies for grain quality traits and correlation analysis of mineral element contents on Al-Ahsa rice and some different varieties (Oryza Sativa L.)

One of the most significant goals in plant breeding programs is to generate new rice varieties with increased elements and good grain quality. In this experiment, ten rice genotypes were evaluated for grain quality traits and protein percentage. Also, milled rice of the ten genotypes were used for analysis of mineral elements. The results revealed that mean squares attributable to genotypes were significant for all traits during the two growing seasons, showing the presence of broad genetic variability among genotypes for all traits under consideration. However, the Indica type (Egyptian Yasmin and Giza 182) gave the highest value for grain length (7.10, 6.52 mm) and grain shape (2.87, 2.82 mm) under the two seasons. While, Al-Ahsa Type1 and Al-Ahsa Type2 rice varieties gave the highest values in protein percentage, which gave 10.80 and 9.80%. Correlation coefficients among the nine grain quality traits clarifying eight absolute positive correlation grain length with grain shape, grain width with hulling % and head rice %; grain shape with amylose content %; hulling % with milled rice and head rice %; milled rice % with head rice %; head rice % with gelatinization temperature. On the other hand, there were seven absolute negative correlations between grain length with grain width; grain width with grain shape and amylose content %; grain shape with hulling % and head rice %; amylose content % with milled rice %, head rice % and gelatinization temperature. In micronutrient elements Al-Ahsa Type1 and Al-Ahsa Type2 varieties gave the heights value for N, P, K, Mg %. Also, gave the heights value for Na (73.25, 73), Fe (20.12, 19.80), and Zn (125.60, 122.70). Pearson’s correlation observed eight absolute positive and significant correlations, which were between; nitrogen content (N), P, K, Mg, Na, Fe, Zn, Cu and protein percentage.     

QTLs affecting kernel size and shape in a two-rowed by six-rowed barley cross

The suitability of barley ( Hordeum vulgare L.) grain for malting depends on many criteria, including the size, shape and uniformity of the kernels. Here, image analysis was used to measure kernel size and shape attributes (area, perimeter, length, width, F-circle and F-shape) in grain samples of 140 doubled-haploid lines from a two-rowed (cv Harrington) by six-rowed (cv Morex) barley cross. Interval mapping was used to map quantitative trait loci (QTLs) affecting the means and within-sample standard deviations of these attributes using a 107-marker genome map. Regions affecting one or more kernel size and shape traits were detected on all seven chromosomes. These included one near the vrs1 locus on chromosome 2 and one near the int-c locus on chromosome 4. Some, but not all, of the QTLs exhibited interactions with the environment and some QTLs affected the within-sample variability of kernel size and shape without affecting average kernel size and shape. When QTL analysis was conducted using data from only the two-rowed lines, the region on chromosome 2 was not detected but QTLs were detected elsewhere in the genome, including some that had not been detected in the analysis of the whole population. Analysis of only the six-rowed lines did not detect any QTLs affecting kernel size and shape attributes. QTL alleles that made kernels larger and/or rounder also tended to improve malt quality and QTL alleles that increased the variability of kernel size were associated with poor malt quality.     

Endosperm enzyme activity is responsible for texture and eating quality of cooked rice grains in Japanese cultivars

Eating quality of cooked rice grains is an important determinant of its market price and consumer acceptance. To comprehensively assess the variation of eating-quality traits in 152 Japanese rice cultivars, we evaluated activities of eight endosperm enzymes related to degradation of starch and cell-wall polysaccharides. Endosperm enzyme activities showed a wide range of variations and were lower in recently developed cultivars than in landraces and old improved cultivars. Activities of most endosperm enzymes correlated significantly with the eating-quality score and surface texture of cooked rice grains. Principal component analysis revealed that rice cultivars with high eating-quality scores had high stickiness of the grain surface and low levels of endosperm enzyme activities. These results suggest that endosperm enzyme activities control texture and eating quality of cooked rice grains in Japanese rice cultivars.     

灌浆期气温与源库强度对稻米品质的影响及其生理分析

利用自然条件下的早、晚季种植作为温度处理,选择米质低、中、优等级的6个水稻品种（组合）作为供试材料,研究了早、晚季种植下的稻米品质、淀粉分支酶活性变化,以及温度处理间的差异.结果表明,在籽粒灌浆初期,高温环境下灌浆充实的籽粒,其稻米的垩白增加、透明度变差、整精米率下降,对出糙率及精米率没有明显影响.与早季种植的稻米相比,晚季种植稻米的胶稠度、整精米率、透明度增加.早、晚季种植对稻米直链淀粉含量、蛋白质含量等没有显著影响.剪叶限源处理显著降低稻米质量,疏粒减库处理显著提高稻米品质.     

Enhancement of Ultrasonic Seed Treatment on Yield,Grain Quality Characters,and 2-Acetyl-1-Pyrroline Biosynthesis in Different Fragrant Rice Genotypes

Fragrant rice is popular for the good grain quality and special aroma. The present study conducted a field experiment to investigate the effects of ultrasonic seed treatment on grain yield, quality characters, physiological properties and aroma biosynthesis of different fragrant rice genotypes. The seeds of three fragrant rice genotypes were exposed to 1 min of ultrasonic vibration and then cultivated in paddy field. The results of present study showed that ultrasonic seed treatment increased grain yield of all fragrant rice genotypes but the responses of yield formation to ultrasonic were varied with different genotypes. Compared with control, ultrasonic seed treatment increased grain 2-acetyl-1-pyrroline (2-AP, the key component of fragrant rice aroma) content by 13.40%–44.88%. Ultrasonic seed treatment also reduced the crude protein contents in grains. The head rice rate, rice length, chalky rice rate, and chalkiness degree were influenced by ultrasonic for one or two fragrant rice genotypes. The activities of peroxidase and superoxide dismutase were also enhanced due to ultrasonic seed treatment. In conclusion, ultrasonic seed treatment increased grain, regulated grain aroma and quality, and improved stress resistance of fragrant rice varieties.