Detecting relationships between amylose content and amino acid contents of <Emphasis Type="Italic">indica</Emphasis> rice with conditional approach

The relationship between the genetic effects of endosperm, cytoplasm and maternal plant on amylose content (AC) and amino acid contents of indica rice was studied using unconditional and conditional analysis methods. The results indicated that the protein content (PC) and brown rice weight (WBR) could significantly affect the relationships between AC and amino acid contents of rice. The phenotypic and genotypic covariances between AC and amino acid contents were most significantly negative under the interference of PC or WBR, but most of the relationships for the paired traits were not significant after excluding the influence of PC or WBR on AC. For the conditional genetic relationship analysis of different genetic systems including endosperm, cytoplasm and maternal plant, visible changes were found in many genetic correlation components between AC and amino acid content after eliminating the influences of PC, especially, for the endosperm or maternal additive effects, endosperm additive or dominance interaction effects and maternal additive interaction effects. The relationships of the paired traits conditioned on WBR were mainly controlled by the endosperm dominance or additive interaction effects.     

籼米淀粉粘滞性的基因型与环境互作研究

水稻精米中大约含有90%的淀粉,因此淀粉的特性对水稻的食味品质有很大的影响.淀粉粘滞性是预测稻米食用、蒸煮和加工品质的重要指标.本研究利用4个细胞质雄性不育系和8个恢复系配置的不完全双列杂交组合来分析淀粉粘滞性指标(崩解值、回复值和消减值)的胚乳、细胞质和母体基因效应及环境互作效应.结果表明在崩解值、回复值和消减值的遗传变异中,遗传主效应方差分量占了64%以上,表明它们主要受遗传主效应控制,同时也受到基因型与环境互作效应的影响.崩解值、回复值和消减值的总遗传率分别为67.8%、79.5%、79.5%,而且普通遗传率占了总遗传率的75%以上,表明对这些性状的早世代选择有效,且在不同环境中选择效果相对稳定.     

籼稻稻米蛋白质含量与外观品质性状间不同遗传体系的条件遗传相关分析

选用稻米蛋白质含量等品质差异较大的7个籼型不育系(A)及相应的保持系(B)与5个籼型恢复系(R)杂交,组成7×5不完全双列杂交组合。应用包括胚乳、细胞质和母体植株基因的遗传主效应以及基因型×环境互作效应的数量性状遗传模型及非条件和条件分析方法,研究了籼稻稻米蛋白质含量与外观品质性状间的遗传相关性,进一步揭示了籼稻糙米重、稻米直链淀粉含量对稻米蛋白质含量与外观品质性状间遗传相关性的影响。非条件分析的结果表明,除了与糙米厚的相关性未达到显著水平以外,蛋白质含量与其它稻米外观品质性状间的遗传相关性均达极显著水平,其中与糙米宽间的相关性表现为正值,其余为负向相关。条件分析的结果显示,糙米重和直链淀粉含量对稻米蛋白质含量与外观品质性状间的遗传相关性均可产生较大的影响。糙米重主要通过基因型×环境互作效应影响蛋白质含量与外观品质性状间的遗传相关性,其中对蛋白质含量与糙米长、糙米宽、糙米厚间遗传相关性的影响主要表现为负向作用,而对蛋白质含量与糙米长宽比、糙米长厚比间遗传相关性的影响则表现为正向作用。稻米直链淀粉主要通过细胞质遗传主效应和母体加性效应影响蛋白质含量与糙米长、糙米长宽比、糙米长厚比间的遗传相关性,而对蛋白质含量与糙米宽间的相关性影响主要表现为负向作用。     

Analysis of Genotype × Environment Interaction Effects for Starch Pasting Viscosity Characteristics in Indica Rice

Milled rice (Oryza sativa L.) is composed of approximately 90% starch. The properties of starch have considerable effects on cooked rice palatability and consumer acceptability. Starch pasting viscosity parameters serve as important indices in the estimation of eating, cooking, and processing qualities of rice. In the present study, four cytoplasmic male-sterile (CMS) lines and eight restorer (R) lines have been used in an incomplete diallel cross to analyze seed effects, cytoplasmic effects, maternal gene effects, and their genotype × environment (GE) effects on the following starch pasting viscosity parameters: breakdown (BD), consistency (CS), and setback (SB). The results demonstrated that the total main genetic variances (V_G) accounted for over 64% of the total genetic variance (V_G + V_GE) for the three traits, indicating that these traits were mainly controlled by the main genetic effects in addition to the GE interaction effects. The estimated total narrow-sense heritability were 67.8%, 79.5%, and 79.5% for BD, CS, and SB, respectively. The general heritability (h²_G) accounted for over 75% of the total heritability (h²_G + h²_GE), indicating that early selection would be effective for those traits and the selection efficiencies were relatively stable in different environments.     

Analysis of genetic effects on nutrient quality traits in indica rice

Nine cytoplasmic male-sterile lines and five restorer lines were used in an incomplete diallel cross to analyze seed effects, cytoplasmic effects, and maternal gene effects on nutrient quality traits of indica rice (Oryza sauva L.). The results indicated that nutrient quality traits were controlled by cytoplasmic and maternal effects as well as by seed direct effects. Maternal effects for lysine content (LC), lysine index (LI), and the ratio of lysine content to protein content (RLP) were more important than seed direct effects, while protein content (PC) and protein index (PI) were mainly affected by seed direct effects. Cytoplasmic effects accounted for 2.41–20.80% of the total genetic variation and were significant for all nutrient quality traits. Additive genetic effects were much more important than dominance effects for all of the traits studied, so that selection could be applied for these traits in early generations.     

Genetic analysis of rice grain quality

 The inheritance of grain quality is more complicated than that of other agronomic traits in cereals due to epistasis, maternal and cytoplasmic effects, and the triploid nature of endosperm. In the present study, an established rice DH population derived from anther culture of an indica/japonica hybrid was used for genetic analysis of rice grain quality. A total of five parameters, amylose content (AC), alkali-spreading score (ASS), gel consistency (GC), percentage of grain with a white core (PGWC) and the square of the white core (SWC), were estimated for the DH lines and the parent varieties. For each parent, the value of each parameter was relatively stable in three locations, Beijing, Hangzhou and Chengdu, while the differences between the parents were significant for all five parameters. AC showed a bimodal distribution, and the distribution of ASS was skewed toward the value of JX17, while the other three parameters displayed continuous distributions among the DH lines with partially transgressive segregations. For AC, a minor and a major gene were found on chromosomes 5 and 6 respectively. The major gene, which should be an allele of wx, explained 91.9% of the total variation. For GC, two QTLs were identified on chromosomes 2 and 7 respectively. For ASS, a minor and a major gene were both located on chromosome 6. The major gene should be the same locus as the alkali degeneration gene (alk). Genetic linkage between alk and wx was found in QTL mapping. For PGWC, two QTLs were located on chromosomes 8 and 12. Only a minor QTL was found for SWC on chromosome 3. The results and the molecular markers presented here may be useful in rice breeding for grain quality improvement. Received: 24 April 1998 / Accepted: 13 August 1998     

Developmental Genetic Analysis of Brown Rice Weight Under Different Environmental Conditions in indica Rice

Analysis of genetic main effects and genotype×environment (GE) interaction effects for brown rice weight (BRW) at four different filling stages in indica rice ( Oryza sativa L.) was conducted for two-year experimental data by using developmental genetic models and corresponding statistical approaches for quantitative traits of seeds in cereal crops. It was indicated that the genetic main effects and their GE interaction effects of triploid endosperm, cytoplasmic and diploid maternal plant genes were important for BRW at different filling stages of rice, especially for endosperm or maternal additive main effects and their additive interaction effects. Because of the higher additive effects and additive interaction effects for BRW at different filling stages, the better improving effects for this trait could be expected by selection in rice breeding. The results of conditional genetic variance components showed that the new expression of quantitative genes in endosperm and maternal plant for BRW was mostly found at all different filling stages of rice. The gene expression, however, was most active at the early filling stages especially for the first (1-7 d) and the second filling stages (8-14 d after flowering). The phenomena that some genes were spasmodically expressible among filling stages of rice were detected for some genetic effects especially for net cytoplasmic main effects or its interaction effects and net dominance main effects. Predicted genetic effects at different filling stages of rice showed that some parents such as V20 and Zuo 5 were better than others for improving the BRW.     

The QTL analysis on maternal and endosperm genome and their environmental interactions for characters of cooking quality in rice (<Emphasis Type="Italic">Oryza sativa</Emphasis> L<Emphasis Type="Italic">.</Emphasis>)

Investigations to identify quantitative trait loci (QTLs) governing cooking quality traits including amylose content, gel consistency and gelatinization temperature (expressed by the alkali spread value) were conducted using a set of 241 RIL populations derived from an elite hybrid cross of “Zhenshan 97” × “Minghui 63” and their reciprocal backcrosses BC₁F₁ and BC₂F₁ populations in two environments. QTLs and QTL × environment interactions were analyzed by using the genetic model with endosperm and maternal effects and environmental interaction effects on quantitative traits of seed in cereal crops. The results suggested that a total of seven QTLs were associated with cooking quality of rice, which were subsequently mapped to chromosomes 1, 4 and 6. Six of these QTLs were also found to have environmental interaction effects.     

籼型黑米粒形性状的遗传效应及其与矿质元素含量的遗传相关性

采用禾谷类作物种子数量性状的遗传模型,分析了灿型黑米稻品种双列杂交F1和F2种子的粒重,粒长,粒宽和粒长／粒宽等粒形性状的遗传效应及其与米粒中矿质元素Fe,Zn,Mn和P含量的遗传相关性,结果表明：4种粒形性状同时受制于种子直接遗传效应,母体效应和细胞质作用影响,其中种子直接遗传效应比母体效应和细胞质效应的作用更大,且种子直接遗传效应以加性效应占主导,粒重,粒宽和粒长／粒宽的种子直接遗传率较高,杂种早代单粒选择效果较好,粒长的种子直接遗传率和母体遗传率均属中等,较高世代的杂种进行单株选择和单粒选择均有一定效果,4种粒形性状与其米粒中矿质元素Fe,Zn,Mn和P含量表现较强的种子直接加性相关,直接显性相关,细胞质相关,母体加性相关和母体显性相关,在特种稻育种实践中,可以通过粒形性的间接选择,达到改良其矿质元素含量等营养品质性状的目标。     

水稻蒸煮品质相关QTL定位及候选基因分析

挖掘与稻米蒸煮品质相关的数量性状基因座(quantitative trait locus, QTL)，分析候选基因，并通过遗传育种手段改良稻米蒸煮品质相关性状，可有效提升稻米的口感。以籼稻华占(Huazhan, HZ)、粳稻热研2号(Nekken2)及由其构建的120个重组自交系(recombinant inbred lines, RILs)群体为实验材料，测定成熟期稻米的糊化温度(gelatinization temperature, GT)、胶稠度(gel consistency, GC)和直链淀粉含量(amylose content, AC)。结合高密度分子遗传图谱进行QTL定位，共检测到26个与稻米蒸煮品质相关的QTLs (糊化温度相关位点1个、胶稠度相关位点13个、直链淀粉含量相关位点12个)，其中最高奇数的可能性(likelihood of odd, LOD)值达30.24。通过实时荧光定量PCR (quantitative real-time polymerase chain reaction, qRT-PCR)分析定位区间内候选基因的表达量，发现6个基因在双亲间的表达量差异显著，推测LOC_Os04g20270和LOC_Os11g40100的高表达可能会极大地提高稻米的胶稠度，而LOC_Os01g04920和LOC_Os02g17500的高表达以及LOC_Os03g02650和LOC_Os05g25840的低表达有助于降低直链淀粉含量。这些结果为培育优质水稻新品种奠定了分子基础，并为揭示稻米蒸煮品质的分子调控机制提供了重要的遗传资源。     

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.     

Mapping quantitative trait loci underlying the cooking and eating quality of rice using a DH population

The cooking and eating quality of rice has attracted more attention recently. In a comprehensive effort to unravel its genetic basis, we conducted a genome-wide analysis of six traits representing the cooking and eating quality of rice grain, namely, amylose content (AC), gel consistency (GC), gelatinization temperature (GT), water absorption (WA), cooked rice elongation (CRE) and volume expansion (VE) using a DH population derived from the anther culture of an F₁ hybrid between WYJ 2 (japonica) and Zhenshan 97B (indica). For each trait, one to three quantitative trait loci (QTL) were found, which were located on chromosomes 1, 2, 3, 6, 11. QTL analysis revealed a major QTL specifying GT, located at the interval RM276-RM121, which should be the same locus as the alkali degeneration gene (alk), while for each of the remaining five traits the QTL explaining the largest proportion of variance was located on the short arm of chromosome 6, centered at RM190 (found in the waxy gene). Our results, in combination with previous reports, further confirmed that either the waxy gene itself or a genomic region tightly linked to it plays a major role in determining the cooking and eating quality of rice.     

籼粳交稻米蒸煮品质性状的遗传效应分析

以2个粳型光温敏核不育系和4个籼稻品种为材料,配制籼粳交组合,用包括基因型×环境互作效应的胚乳性状遗传模型对3个蒸煮品质性状(直链淀粉含量、胶稠度、碱消值)进行了遗传研究,结果表明:直接加性和母体加性效应对三个性状的遗传变异起主要作用.基因型×环境互作主要表现为显性×环境以及细胞质×环境互作.直链淀粉含量的普通遗传率都不显著,只有较高的互作母体遗传率;胶稠度具有显著的普通直接遗传率和互作细胞质遗传率;碱消值的普通直接遗传率和普通母体遗传率都极显著.根据遗传效应预测值对供试亲本的利用价值作了评价。     

Analysis of the genetic behavior of some starch properties in indica rice ( Oryza sativa L.): thermal properties,gel texture,swelling volume

Starch comprises about 90% of milled rice, so that the eating and cooking quality of rice is mainly affected by the starch properties. In the present paper, we analyzed the genetical behavior of gelatinization temperature tested by differential scanning calorimetry (DSC), gel texture, and the swelling volume (SV) of indica rice with an incomplete cross of 4×8 parents. A genetic model which can dissect the effects of triploid seed, the cytoplasm, and the maternal plant on the endosperm traits was used. The results indicated that peak temperature (T_p), conclusion temperature (T_c) and enthalpy (ΔH) were controlled by three types of genetic effects: seed direct (endosperm) effects, cytoplasmic effects and maternal effects. No cytoplasmic effects for the onset temperature (T_o), hardness and SV, and no maternal effects for cohesiveness were found. The additive variances (V _A +V _Am ) were larger than the dominance variances (V _D +V _Dm ) for all the traits except for T_c, which suggested that selection could be applied for the starch properties in early generations. The total narrow-sense heritability for each parameter was over 60%, indicating that selection advances were predictable in the early generations for these traits. Received: 17 February 2001 / Accepted: 17 May 2001     

水、旱条件下稻米蒸煮和营养品质性状与土壤水分环境互作分析及其QTL定位

以旱稻品种IRAT109与水稻品种越富杂交构建的DH群体的116个株系及其亲本为材料,在水、旱2种栽培条件下种植,研究了稻米蒸煮和营养品质性状的变化规律,在水、旱2个土壤水分环境下对直链淀粉含量(AC)、胶稠度(GC)、碱消值(GT)和蛋白质含量(PC)4个蒸煮和营养品质性状进行QTL定位及QTLs与环境互作分析。结果表明,以上4个品质性状在水、旱2种不同栽培条件下差异较大,说明这些性状受水分条件影响较大,旱栽条件下稻米蒸煮和营养各品质性状均有不同程度的升高,其中蛋白质含量平均提高37.9%。QTL分析结果表明,4个稻米品质性状在2个环境中的表现型值都为连续分布,均存在超亲遗传类型,共检测到7个加性效应QTL与稻米蒸煮和营养品质性状4项指标有关,分别位于第1、2、3、6、8、11染色体上,单个QTLs对性状的贡献率在1.91%～19.77%之间。位于第3染色体上控制碱消值的QGt3,第6染色体上控制直链淀粉含量的QAc6,在2个不同土壤水分条件下均与环境存在显著互作,对环境互作的贡献率分别为8.99%和47.86%。控制直链淀粉含量的2对上位性QTLs与土壤水分环境显著互作,贡献率较大,分别为32.54%和11.82%。并筛选到5个主效QTL(QGt6b、QGt8、QGt11、QGc1和QPc2)在抗旱育种中可用于蒸煮和营养各品质性状MAS改良。     

籼粳杂交稻穗部性状的遗传效应及其与环境互作

采用包括基因型与环境互作效应的加性-显性-加性×加性上位性遗传模型,分析了不同环境下籼粳杂交稻穗部性状的遗传特点.结果表明,除了主穗粒数的加性与环境互作和二次枝梗数的显性与环境互作不显著外,其他性状均存在显著和极显著的加性、显性、加性×加性上位性遗传效应及其与环境的互作效应,其中均以显性效应为主,显性与环境互作效应对枝梗性状的影响较为明显.遗传率分析表明,各性状的普通广义遗传率最大,互作遗传率也有一定作用.杂种优势预测表明,除了一次、二次枝梗数外,其他性状均表现正向的杂种优势,基因型与环境互作只影响杂种优势表达的程度,而不改变其方向.遗传效应预测值结果表明,IR66158-37、IR65600-85、明恢63和R6694个亲本可以明显改良杂交后代多数穗部性状,且环境影响程度较小,可作为优良亲本列于育种计划中.     

Genetic basis of 17 traits and viscosity parameters characterizing the eating and cooking quality of rice grain

A recombinant inbred line population derived from a cross between Zhenshan 97 and Delong 208 was used to analyze the genetic basis of the cooking and eating quality of rice as reflected by 17 traits (or parameters). These traits include amylose content (AC), gel consistency (GC), alkali spreading value (ASV), cooked rice elongation (CRE), and 13 parameters from the viscosity profile. All the traits, except peak paste viscosity (PKV), time needed from gelatinization to peak (BAtime), and CRE, can be divided into two classes according to their interrelationship. The first class consists of AC, GC, and most of the paste viscosity parameters that form a major determinant of eating quality. The second class includes ASV, pasting temperature (Atemp) and pasting time (Atime), which characterize cooking process. We identified 26 QTL (quantitative trait locus or loci) in 2 years; nine QTL clusters emerged. The two major clusters, which correspond to the Wx and Alk loci, control the traits in the first and second classes, respectively. Some QTL are co-located for the traits belonging to the same class and also for the traits to a different class. The Wx locus also affects on ASV while the Alk locus also makes minor contributions to GC and some paste viscosity parameters. The QTL clusters on other chromosomes are similar to the Wx locus or Alk locus, although the variations they explained are relatively minor. QTL for CRE and PKV are dispersed and independent of the Wx locus. Low paste viscosity corresponds to low AC and soft gel, which represents good eating quality for most Chinese consumers; high ASV and low Atemp, together with reduced time to gelatinization and PKV, indicate preferred cooking quality. The genetic basis of Atemp, Atime, BAtime, peak temperature, peak time, paste viscosity at 95 degrees C, and final paste viscosity is newly examined to reveal a complete and dynamic viscosity profile.     

The main effects, epistatic effects and environmental interactions of QTLs on the cooking and eating quality of rice in a doubled-haploid line population

Amylose content (AC), gel consistency (GC) and gelatinazation temperature (GT) are three important traits that influence the cooking and eating quality of rice. The objective of this study was to characterize the genetic components, including main-effect quantitative trait loci (QTLs), epistatic QTLs and QTL-by-environment interactions (QEs), that are involved in the control of these three traits. A population of doubled haploid (DH) lines derived from a cross between two indica varieties Zhenshan 97 and H94 was used, and data were collected from a field experiment conducted in two different environments. A genetic linkage map consisting of 218 simple sequence repeat (SSR) loci was constructed, and QTL analysis performed using qtlmapper 1.6 resolved the genetic components into main-effect QTLs, epistatic QTLs and QEs. The analysis detected a total of 12 main-effect QTLs for the three traits, with a QTL corresponding to the Wx locus showing a major effect on AC and GC, and a QTL corresponding to the Alk locus having a major effect on GT. Ten digenic interactions involving 19 loci were detected for the three traits, and six main-effect QTLs and two pairs of epistatic QTLs were involved in QEs. While the main-effect QTLs, especially the ones corresponding to known major loci, apparently played predominant roles in the genetic basis of the traits, under certain conditions epistatic effects and QEs also played important roles in controlling the traits. The implications of the findings for rice quality improvement are discussed.     

Genetic and genotype × environment interaction effects for the content of seven essential amino acids in<Emphasis Type="Italic">Indica</Emphasis> rice

It is necessary for rice breeders to understand the genetic basis of nutrient quality traits of rice. Essential amino acids are most important in determining the nutrient quality of rice grain and can affect the health of people who depend on rice as a staple food. In view of the paucity of genetic information available on essential amino acids inindica rice, we estimated the genetic main effects and genotype × environment (G × E) interaction effects on the content of essential amino acids. Nine cytoplasmic male sterile lines as females and five restorer lines as males were introduced in a North Carolina II design across environments. Estimates of the content of the essential amino acids valine, methionine, leucine and phenylalanine showed that they were mainly controlled by genetic main effects, while the contents of threonine, cysteine and isoleucine were mainly affected by G × E effects. In the case of genetic main effects, both cytoplasmic and maternal genetic effects were predominant for all essential amino acids, indicating that selection for improving essential amino acid content based on maternal performance would be more effective than that based on seeds. The total narrow-sense heritabilities were high and ranged from 0.72 to 0.83. Since general heritabilities for these essential amino acids (except for cysteine) were found to be much larger than G × E interaction heritability, the improvement of content of most essential amino acids under selection would be expected under various environments. Rice varieties such as Zhenan 3, Yinchao 1, T49, 26715, 102 and 1391 should be selected as optimal parents for increasing the content of most essential amino acids, while the total genetic effects from Zhexie 2, Xieqingzao, Gangchao 1, V20, Zuo 5 and Zhenshan 97 were mainly negative and these parents could decrease the contents of most essential amino acids.     

Genetic analysis of non-essential amino acid contents in rice (Oryza sativa L.) across environments

Genetic main effects and genotype x environment (GE) interaction effects for 7 non-essential amino acids in milled rice were analyzed for two year data by using the genetic models based on mixed linear model approaches for quantitative traits of triploid endosperm. Nine cytoplasmic, male sterile lines as females and five restoring lines as males were introduced in a diallel cross in two environments. It was found that the content of non-essential amino acids including Asp, Ser, Glu, Gly and Tyr were mainly controlled by genetic main effects, whereas the content of Ala or Pro was mainly affected by GE effects. In genetic main effects, the cytoplasmic and maternal genetic effects were preponderant for all traits of non-essential amino acids, indicating that selection for improving these traits based on the maternal plant would be more effective than on seeds. The total narrow-sense heritabilities for non-essential amino acids were 70.9-85.9%. By predicating the genetic effects of parents, the total genetic effects from Xieqingzao, V20, Zuo 5 and Zhenshan 97 were mainly negative and these parents would decrease the content of most essential amino acids. Since parents of Zhenan 3, Yinchao 1, T49, 26715, 102 and 1391 had possessed a positive value of most total genetic effects, these parents could be chosen as optimal parents for increasing the content of most non-essential amino acids.