Distribution of the Classification Traits in the F_2 Progeny of Two Crosses of indica/japonica in Rice (Oryza sativa)

Comparison of seed setting rate, plant height and Cheng's morphological traits were made between the F_2 progeny of indica-japonica hybrids, 02428/Pei'ai 64 and Taichung 65/Teqing. There existed resemblance normal distribution in plant height, and the distribution had no relationship with the seed setting rate and plant height in F_1 progeny, suggesting that there were no gametic selection for the plant height in the F_2 progeny of indica-japoniea hybrids. An average seed setting rate of the F_2 was equal to the F_1 populations in the recombination of 02428/Pei'ai 64 in which there was an excellent cross compatibility, but the remarkable increase in the seed setting rate from the F_1 to F_2 in Taichung 65/Teqing, indicating that gametic selection only took place in the indica-japonica crosses with low cross compatibility while null or little in the hybrids with high compatibility. There were many intermediate types among the leaf pubescence, color of hull at heading, and length of the first and second panicle internode, and these Cheng's morphological traits was distributed normally; there were also a little intermediate types in hull hairness and phenol reaction with bi-peak distribution; while length to width ratio of grain was inclined to the japonica types obviously showing a skewed distribution in the F2 population. Although Cheng's morphological traits in F_2 populations had inconsistent distribution types, Cheng's morphological traits index showed normal distribution, which suggested that intermediate types, i.e. indicalinous or japonicalinous, were primary in F_2 population.

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.

Genetic analysis of quality traits in intersubspecies crosses of rice

Indica and japonica rices are two subspecies ofAsia cultivated rice.Their grain qualities exista significant difference.The objective of thispaper is to study the genetic control of qualitytraits in intersubspecies crosses of rice.In 1991,4 japonica varieties with widecompatibility,PC311,Zhenxiqiuguang,Lun-hui 422,and Ce 03 were crossed with 5 indicavarieties,3037,Zaoxiandang 18,IR36,Minghui 63,and Yangdao 4 according to NC(?)design.The 20 hybrids using japonica as ma-

A Preliminary Study on the Relationship Between the Indica-Japonica RAPD Differentiation of Parents and Heterosisin Dian Type Hybrid Rice

The relationship between the indica-japonica differentiation of parents and heterosis of hybrid in rice was studied with 10 sterile lines, 10 maintainer lines of the sterile lines, 38 restorer lines of Dian type hybrid rice and 40 hybrids derived from the sterile lines and restorer lines. The results indicated that there was a parabolic correlation between the indica-japonica differentiation of parents detected by RAPD markers and heterosis of hybrid rice. When certain indica-japonica differentiation of parents exists, the percentage of combinations with positve heterosis and the mean heterosis of hybrids were high. But that didn't mean too much difference of parents could lead to stronger hetesosis, that meant overdiffernt parents seldom bring positve het-erotic hybrids. Suitable difference of percent of indica alleles of parents of stronger heterotic hybrid was 12 -16%.

Analysis of Indica-Japonica Differentiation in Rice Parents and Derived Lines Using ILP Markers

Revealing the indica-japonica differentiation in parents of hybridization between indica and japonica rice and their derived lines can provide theoretical and practical bases for the breeding of practical inter-subspecific hybrid rice. Using subspeciesspecific molecular markers ILP （intron length polymorphism） and Cheng＇s index, the indica-japonica differentiation was analyzed with special materials including 18 indica-japonica hybrid parents and 39 derived lines, which accumulated different wide compatibility and restoring genes by convergent cross method in 21 years spanning four breeding phases. The indica-japonica differentiation was detected on all tested loci in 57 materials. Among the 18 parental lines, 4 were japonica type, 5 japonicaclinous type, 8 indicaclinous type and one indica type. The japonica proportion indexes in indica restorer lines Minghui 63 and 9308 were 12.50 and 33.33 %, respectively, while that in japonica restorer line C418 was only 31.25%. Among the 39 derived lines from indica-japonica hybridization, one was japonica type, 11 japonicaclinous type, 20 indicaclinous type and 7 indica type. The japonica proportion index in Minghui 502 was only 10.42%. The results of indica and japonica classification by ILP molecular markers and Cheng＇s index were relatively consistent. The correlation coefficient between the japonica proportion index and morphology index was 0.794＊＊, while that between the indica proportion index and morphology index was -0.7662＊＊. ILP markers could be used to accurately detect the proportion of indica/japonica content in the genome of a rice variety. The results of indica-japonica differentiation analysis could make reasonable explanation for that the hybrids obtained from indica-japonica type restorer lines had obvious heterosis. This conclusion would provide important guidance in efficient use of beneficial genes of inter-subspecific hybrid rice.

Relationship of Parental Indica-Japonica Indexes with Yield and Grain Quality Traits of Japonica Hybrid Rice in Northern China

Taking the main parents （10 male sterile lines and 10 restorer lines） and their 100 combinations of japonica hybrid rice in northern China as materials, the relationships of parental indica-japonica indexes determined by the methods of the Cheng’s index as well as simple sequence repeat （SSR） markers with yield and grain quality traits of hybrid rice were studied. For the parents, the Cheng’s index （Chi） ranged from 13.5 to 19.3 and the indica index in SSR markers （ADi） were from 0.12 to 0.38. The classification of parents by Chi was not completely consistent with that by ADi. The Chi of male parent was more closely related to hybrid traits than that of female parent, as contrasted to ADi. At the same time, the difference between parents （PD） in Chi was more closely related to hybrid traits than that in ADi. The indica-japonica indexes of parents and their difference between parents appeared quadratic relationship to hybrid traits with the critical extremum. The directions of the correlation of indica-japonica indexes of parents and their differences with hybrid yield traits were on the opposition to those with hybrid grain quality traits. Therefore, the female parent should match the male parent moderately in indica-japonica index to obtain the optimum of hybrid traits, high yield as well as good quality.

Effects of chilling tolerance induced by spermidine pretreatment on antioxidative activity,endogenous hormones and ultrastructure of indica-japonica hybrid rice seedlings

Spermidine（Spd） is known to be involved in the regulation of plant responses to chilling stress and counteract the adverse effect of stress conditions.Antioxidant activities,endogenous hormones and ultrastructure change under chilling stress were investigated in indica-japonica hybrid rice seedlings.12-d-old seedlings were subjected to exogenous Spd（1 mmol L^（-1）） and then a chilling stress（6℃,4 d） was induced,followed by a subsequent recovery（25℃,4 d）.Results showed that malondialdehyde（MDA） and proline content were enhanced significantly,whereas shoot fresh and dry weights decreased during chilling stress and after recovery;chlorophyll content of chilling-stressed seedlings increased slightly but declined after recovery;additionally,total soluble sugar,sucrose,fructose and starch contents increased significantly during chilling stress,and only soluble sugar and fructose contents were observed in increase after recovery;chilling stress-induced increases in superoxide dismutase（SOD）,peroxidase（POD） and catalase（CAT） activities,but declined after recovery,and the level of ascorbate peroxidase was lower during chilling stress and after recovery;however,endogenous indole-3-acetic acid（IAA）,zeatin riboside（ZR）,gibberellic acid（GA_3）,and abscisic acid（ABA） levels were induced decreased compared with Spd pretreatment.The microscopic analysis revealed that chilling stress-induced destruction of the chloroplast envelope during chilling stress and increased the number of plastoglobuli along with aberrations in thylakoid membranes after recovery.In contrast,exogenous Spd protected rice seedlings from chilling-induced injuries in terms of lower malondialdehyde,proline and carbohydrates accumulation coupled with increased endogenous hormones metabolism.After recovery,Spd pretreatment chilling-exposed seedlings showed higher activities of antioxidant enzymes and normal physiological function of chloroplasts.These results suggest that Spd could promote effectively chilling tolerance which might be largely attributable to the integrity of cell structure and normal metabolism of endogenous hormones in indica-japonica hybrid rice seedlings.

Subspecific Characteristics and Classification of Rice Varieties Developed Through Indica and Japonica Crossing

Six characteristics, i.e., hull color, chaff and leaf pubescences, length of 1st and 2nd rachis, grain length/width ratio andphenol reaction, of rice progenies from indica and japonica crossing were studied using the Chengs index classificationmethod. The results indicated that F1 generations performed more like indica, while F2 generations were approximately ina normal distribution. Both of the rice progenies were more affected by indica and female parents than by japonica andmale parents. Among the six Chengs index traits of the parents and F1 generations, and between the traits and Chengsindexes, significant correlations (both at a=0.05 and a=0.01) were found in most cases. No significant correlations werefound among the 6 Chengs index traits of F2 generations in most cases, but significant correlations (a=0.01) existedbetween these traits and Chengs indexes. The six Chengs index traits of F2 ranged successively, and many individualsshowed over-parent genetics, with the same trends in both direct cross and reciprocal cross. Among the 6 index traits,chaff and leaf pubescences almost presented in a two-peak value, while the others in a mono-peak value. The hull color,phenol reaction and length of 1st and 2nd rachis were distributed in deviation, with the first two traits presented more injaponica individuals and the last trait more in indica. The grain length/width ratios were nearly in a normal distribution.

Developmental Analysis of Genetic Behavior of Brown Rice Width in indica-japonica Hybrids

The developmental genetic behaviors of brown rice width （BRW） have been studied in indica-japonica hybrid rice （Oryza sativa L.）, in which seven indica male sterile lines and five japonica restorer lines were applied, by using the developmental genetic models and corresponding statistical approaches for quantitative traits of triploid in cereal crops. The BRW of indica-japonica hybrid rice was co-determined by gene expression of tdploid endosperm, cytoplasm, diploid maternal plant and their genotype × environmental interaction effects. Unconditional analysis showed that the endosperm additive and matemal additive effects were predominant for the development of BRW from early- to late-stage of the grain development, but the endosperm dominant effect together with matemal effect and cytoplasmic effect became the major factor determing the BRW at the ripening stage. Moreover, conditional analysis found that there were new onset and offset of gene expression at different developmental stages of BRW in indica-japonica hybrid rice. Maternal and cytoplasm general heritabilities and their interaction heritabilities were more important compared to other components of heritability for BRW at all the five developmental stages.

Genetic Analysis of Leucine Content in Indica-Japonica Hybrid Rice (Oryza sativa L.)

Genetic control of leucine content in indica-japonica hybrid rice (Oryza sativa L.) was studied in 35 crosses of F1 and F2 generations, which were derived from crossing 7 male sterile indica rice lines with 5 restorer japonica rice lines along with their parents. Two genetic models and their corresponding statistical methods for quantitative traits of triploid seeds in cereal crops were used for the analysis. The first was the unconditional genetic model, which refers to the analysis of cumulative measurements (from flowering to a specific time) along the developmental stages, while the second was the conditional genetic model, which relates to analysis from one developmental stage to another stage (t - 1→t). The results showed that leucine content of indica-japonica hybrid rice was controlled by the expression of triploid endosperm effect (endosperm additive effect and endosperm dominant effect), cytoplasm effect, diploid maternal plant effect (maternal additive effect and maternal dominant effect) and their environmental interaction effects. Of these effects, endosperm dominant effect and maternal dominant effect were more important at the earlier stages, while endosperm additive effect and maternal additive effect were more important at the later stages of rice grain development under both unconditional and conditional genetic analyses. Due to the high heritabilities, which came from endosperm, maternal and cytoplasm effects for leucine content at different developmental stages, selection for leucine content of indica-japonica hybrid rice would be more efficient at early generations in breeding programs.

基于YOLOv5-RF的糙米内部裂纹识别方法研究

[目的]为准确识别糙米内部裂纹,提出了一种基于改进YOLOv5l的糙米裂纹识别算法——YOLOv5-RF。[方法]使用深度卷积代替CBS(convolution+batch normalization+sigmoid linear unit)模块中的普通卷积构建出DWBS(depthwise convolution+batch normalization+sigmoid linear unit)模块,然后将DWBS模块堆叠成辅助骨干网络,再与原始的Darknet-53主干网络相结合形成基于DWBS模块的同级复合骨干网络,以提高糙米内部裂纹特征提取能力;在颈部网络使用逆向连接层来增强解码端特征的丰富性,用于提高解码端对糙米内部裂纹的识别能力;利用CBAM(convolutional block attention module)注意力模块调整SPPF(spatial pyramid pooling-fast)模块的通道注意力表达,通过构建一种SPPF模块与CBAM模块结合的网络结构来提高编码阶段的语义信息表达质量。[结果]所提出的YOLOv5-RF算法的平均准确率、召回率和准确率分别为94.01%、86.92%、90.85%,相比YOLOv5l算法分别提升了4.72%、6.23%、1.23%,但添加模块对模型检测速度的影响却很小。[结论]所提方法能够准确进行糙米内部裂纹的识别,可为稻谷爆腰率检测提供技术参考。

On Significance of Heterotic Group Theory in Hybrid Rice Breeding

Heterotic group theory （HGT） has played a major role in supporting hybrid maize breeding for about 100 years. The basic content and studies of HGT, and its application in rice and maize were summarized in this paper. Additionally, difficulties and challenges for hybrid rice breeding in China were analyzed, and necessity and urgency in hybrid rice breeding by using HGT were proposed.

Discussion on strategy of grain quality improvement for super high yielding japonica rice in Northeast China

japonica rice is mainly distributed in Northeast China and accounts for 44.6% of the total cultivated area of japonica rice in China. The comprehensive using of inter-subspecies heterosis is the main breeding mode of super japonica rice varieties in this region. Improving rice quality at relative high yielding level is the current research focus. Performing crosses between indica and japonica lines allows for the recombination of regulatory genes and genetic backgrounds, leading to complicated genetic rice quality characteristics, which can be used to explore patterns of quality improvement. In the present study, we utilize recombinant inbred lines （RILs） derived from indica-japonica hybridization to analyze the effect factors of rice quality derived from genetic factors, which contain both regulatory genes concerning rice quality and genetic backgrounds＇ random introduction frequency coming from indica （Di value）, and the improvement strategy was further discussed. The regulatory genes involved in amylase content （Wx） and nitrogen utilization efficiency （NRT1.1B） were the major factors affecting the amylose content （AC） and protein content （PC） in RILs, respectively. Both the Di value and the major grain width gene （GS5） had regulatory effects on milled rice width （MRW） in RILs, and their interaction explained the major variance of MRW in the RILs. With the mediation of MRW and chalkiness degree （C）, Di value had a further impact on head rice rate （HR）, which was relatively poor when the Di value was over 40%. In Northeast China, the Di value should be lowered by backcrossing or multiple crosses during the breeding of indica-japonica hybridization to maintain the whole better HR and further to emphasize the use of favorable genes in individual selection.

Status and Prospects of Hybrid Rice Breeding in Jiangsu, China

Research on hybrid rice in Jiangsu Province, China began in 1970. Great progress has been made since then, which can be divided into three stages according to the development of hybrid rice breeding and production in Jiangsu Province. The first stage was beginning stage from 1970 to 1980, when progress was mainly made in cytoplasmic male sterile line breeding. The second stage could be described as developing stage, from 1980 to 1995, when indica hybrid rice was rapidly popularized, and japonica hybrid rice became popular later. From 1996, hybrid rice breeding in Jiangsu Province entered the third stage, when both indica and japonica hybrid rice breeding in the three-line system or intersubspecific hybrid rice breeding in the two-line system made a great breakthrough with the successful breeding of the hybrids Feyou 559, 9 You 138 and Liangyoupeijiu. The developing trend of hybrid rice breeding in Jiangsu Province is also discussed.

An Insect Imaging System to Automate Rice Light-Trap Pest Identification

Identification and counting of rice light-trap pests are important to monitor rice pest population dynamics and make pest forecast. Identification and counting of rice light-trap pests manually is time-consuming, and leads to fatigue and an increase in the error rate. A rice light-trap insect imaging system is developed to automate rice pest identification. This system can capture the top and bottom images of each insect by two cameras to obtain more image features. A method is proposed for removing the background by color difference of two images with pests and non-pests. 156 features including color, shape and texture features of each pest are extracted into an support vector machine （SVM） classifier with radial basis kernel function. The seven-fold cross-validation is used to improve the accurate rate of pest identification. Four species of Lepidoptera rice pests are tested and achieved 97.5% average accurate rate.

Genetic Analysis and QTL Mapping of Large Flag Leaf Angle Trait in Japonica Rice

Genetic segregation analysis for flag leaf angle was conducted using six generations of P1, P2, F1, B1, B2 and F2 derived from a cross of 863B （a maintainer line of japonica rice） and A7444 （a germplasm with large flag leaf angle）. Genotypes and phenotypes of flag leaf angle were investigated in 863B （P1）, A7444 （P2） and 141 plants in BC^F~ （863BIA744411863B） population. An SSR genetic linkage map was constructed and QTLs for flag leaf angle were detected. The genetic map containing 79 information loci was constructed, which covers a total distance of 441.6 cM, averaging 5.6 cM between two neighboring loci. Results showed that the trait was controlled by two major genes plus polygene and the major genes were more important. Fifteen markers showed highly significant correlations with flag leaf angle based on single marker regression analysis. Two QTLs （qFLA2 and qFLA8） for flag leaf angle were detected by both composite interval method in software WinQTLCart 2.5 and composite interval method based on mixed linear model in QTL Network 2.0. The qFLA2 explained 10.50% and 13.28% of phenotypic variation, respectively, and was located at the interval of RM300 and RM145 on the short arm of chromosome 2. The qFLA8 explained 9.59% and 7.64% of phenotypic variation, respectively, and was located at the interval flanking RM6215 and RM8265 on the long arm of chromosome 8. The positive alleles at the two QTLs were both contributed from A7444.

Estimating Out-Crossing Rate of Bg 379-2 Using Morphological Markers and Confirmation by Molecular Markers

Rice is largely self-fertilized and accordingly a field population of rice is completely composed of near homozygotes. Due to the emergence of off-types, homozygosity will be affected. With the time, this will cause the reduction of genetic purity in some rice varieties. One of the reasons has been suspected to be the high out-crossing frequencies of such varieties. Studies were conducted at the Rice Research and Development Institute, Batalagoda, Sri Lanka to estimate the out-crossing rate of Bg 379-2, a variety having the problem of maintaining genetic purity. Bg 379-2 was allowed to out-cross with Bg 450 and the number of out- crossed plants were counted using dominant morphological markers such as short-round grain and purple culm of pollen donor. A molecular confirmation of out-crossing was also performed using sequence tagged site （STS） molecular marker pTA248. The variety Bg 379-2 showed a potential out-crossing rate of 3.41% and an average out-crossing rate of 1.29% using dominant morphological markers. Polymorphism was cleady detected between parents and out-crossed plants as well as selfed plants of Bg 379-2 using their banding patterns. A similar study can be performed to determine the out-crossing rates of other varieties which show high percentage of off-types in the population for the better understanding of the breeding behavior of the varieties.

Rice公式外推桥梁荷载效应

在当今,如何对桥梁进行合理评估已成为桥梁工作者的一个重要课题。而在桥梁评估过程中,科研工作者往往需要定量描述评估周期内某座桥梁的交通车辆荷载大小,一般用荷载效应描述。就此根据动态称重系统实测的107国道路段交通荷载数据产生的模拟车流对评估周期内荷载效应极值的计算方法进行了初步研究,以各种跨径简支梁为例,利用Rice外推理论外推各个观测周期的荷载效应极值,并以此作为建立评估荷载模型的基础。

谷氨酰胺酶催化交联大米蛋白对大米淀粉理化特性的影响

为弄清谷氨酰胺酶(TG)催化交联前、后大米蛋白对大米淀粉理化特性的影响,测定淀粉的膨胀系数与溶解度、直链淀粉溢出率。采用红外光谱法、可见分光光度法、差示扫描量热仪(DSC)、快速粘度分析仪(RVA)等技术手段分析淀粉共混体系的结构特征和功能特性。结果表明,蛋白在TG酶催化下对淀粉的结构、消化率与其它功能特性均有显著影响,且大米蛋白与淀粉二者间相互作用增强,表现为:大米淀粉的膨胀系数由13.24 g/g降至最低,为7.02 g/g,其直链淀粉溢出量降低38.7%。在TG酶作用下,随着蛋白含量的增加,淀粉短程有序结构的稳定性逐渐增强。添加量为10%的蛋白在TG酶的催化下对淀粉消化性减轻效果更好。TG酶作用前、后蛋白对淀粉的热特性影响不大,而其糊化特性参数均明显下降,黏度也显著降低。TG酶催化蛋白使得淀粉颗粒网络结构更加致密且聚集。结论:TG酶催化交联蛋白对淀粉的改性效果显著。

水稻粒型调控基因功能研究进展

水稻是世界上的重要谷类粮食作物之一,其产量和品质一直都是育种学家关注的重点,关系到全球粮食安全和人类健康。水稻粒型主要包括粒长、粒宽、粒厚等,是受多基因控制的重要数量性状,不仅直接影响水稻产量,还与水稻品质密切相关。深入了解水稻粒型的形成与调控机理将有助于进一步提升水稻单株产量、改善稻米品质。分子生物学的发展和基因组学的研究为探究水稻内部调控机制带来了新的变革。大量水稻粒型的数量性状遗传位点(Quantitative trait locus,QTL)成功被鉴定与解析,并验证了与之有关的基因功能。目前,已有几条调控粒型的通路得到鉴定,如泛素-蛋白酶体降解途径、G蛋白信号途径、丝裂原活化蛋白激酶途径、转录因子调控途径、植物激素途径以及表观遗传途径等。然而,粒型调控网络极其复杂,多数基因上下游的调控组件作用机制尚不清楚,甚至影响粒型的各条通路间均存在一定的交叉互作。本文综述了影响水稻粒型的不同信号通路相关基因研究进展及关键粒型基因间的互作关系,总结了近年来粒型基因在育种上的应用情况,并提出结合多组学解析水稻粒型的调控机理研究,以期更好地服务于分子设计育种,为开发新的高产优质稻育种提供支撑。