不同环境下籼型杂交稻穗干物质重的发育遗传分析

选用穗干物质重性状差异较大的 4个籼型不育系 (A)和相应的保持系 (B)以及 5个籼型恢复系(R) ,按不完全双列杂交设计 (4× 5 ) ,配成一套亲本和F12个世代的遗传群体 .采用包括基因型×环境互作的加性 显性发育遗传模型 ,分析了两年的籼型杂交稻不同发育时期穗干物质重的遗传表现 .结果表明 ,穗干物质重的发育全过程均受到遗传主效应和基因型与环境互作效应的控制 .在穗干物质重发育的前、中期 (15d前 )主要由显性效应控制 ,显性效应基因的表达量最大 ,环境因素的正向影响也较明显 ,可通过采取适当的栽培管理措施为稻穗发育创造良好的环境条件 ,促进杂种优势潜力的充分发挥 ;在发育的中后期 (15d后 )加性效应转为主要作用 ,加性效应基因的表达也呈最活跃状态 ,这一时期对穗重进行遗传选择会获得较好的遗传进度 .     

作物杂种后代基因型值和杂种优势的预测方法

本文提出了利用作物亲本和F_1预测杂种后代基因型值和杂种优势的统计分析方法.该方法运用加性-显性遗传模型,分析双列杂交试验资料,用MINQUE(1)法估算方差分量以及预测遗传效应值.由加性和显性效应预测值可进一步预测F_1,F_2,BC_1,BC_2,等不同世代的基因型值,在预测F_1群体平均优势和群体超亲优势的基础上,可以推导出其它各世代的杂种优势.提出了预测杂种后代保持超亲优势世代数的简单公式,根据杂交组合F_1群体平均优势和双亲相对遗传差异,便可预测该组合能在生产上直接利用的世代数.以棉花六个品种完全双列杂交试验资料为例,分析了各组合F_1和F_2的基因型值、超亲优势和保持5％超亲优势的世代数.     

籼型三系杂交水稻地上部干物质重的发育遗传研究

采用数量性状的加性--显性发育遗传模型分析了按NCⅡ交配设计的两套籼型三系杂交水稻地上部干物质重的发育遗传规律．结果表明,在不同发育阶段,地上部干物质重以显性效应为主,控制地上部干物质重的加性效应基因几乎不表达,而显性效应基因在两年中的表达呈连续性,且在生长中期活动强度最大,环境和基因型互作会影响地上部干物质重加性效应基因的表达,而对显性效应基因表达的影响不明显,随着发育进程的推进,地上部干物质重杂种优势趋于减弱。     

水稻苗期抗寒性的杂种优势分析

通过观察12个水稻杂交组合(包括父母本)的苗期叶片的相对电导率和植株的成苗率,来探讨水稻苗期抗寒性的杂种优势.分析表明:在经过4℃、2 d的冷处理后,12个杂交组合的相对电导率的超亲优势值都为负数,中亲优势值在-37.27%～+21.02%之间,成苗率在-30.80%～+7.20%之间,杂种优势表现为中亲优势.     

作物杂种后代基因型值和杂种优良的预测方法

本文提出了利用作物亲本和Ｆ１预测杂种后代基因型值和杂种优势的统计分析方法。该方法运用加性－显性遗传模型,分析双列杂交试验资料,用ＭＩＮＱＵＥ（１）法估算方差分量以及预测遗传效应值。由加性和显笥效应预测值可进一步预测Ｆ１,Ｆ２,ＢＣ１,ＢＣ２,等不同世代的基因型值,在预测Ｆ１群体平均优势和 群丛超亲优势的基础上,可以推导出其它各世代的杂种优势。提出了预测杂种后代保持超亲优热世代数的简单公式,根据杂交组合Ｆ１群体平均优势和双亲相对遗传差异,便可预测该组合能的生产上直接利用的世代数。以棉花六个品种完全双列杂交试验资料为例,分析了各组合Ｆ１和Ｆ２的 基因型值、超亲优势和保持５％超亲优势的世代数。     

羽衣甘蓝裂叶相关性状遗传分析

以羽衣甘蓝圆叶自交系‘0835’和裂叶自交系‘0819’为亲本,调查P1、P2、F1、F2群体莲座期4个裂叶相关性状表型数据,运用‘四世代主基因+多基因’遗传模型,对叶长、叶宽、叶形指数、叶缘缺刻数4个叶形相关性状进行遗传分析,探讨羽衣甘蓝裂叶相关性状的遗传规律,为羽衣甘蓝裂叶性状遗传、QTL定位及新品种选育奠定基础。结果表明:(1)4个性状均存在一定的杂种优势,其中叶缘缺刻数中亲优势达显著水平,4个性状均存在负向超亲优势。(2)叶长和叶宽均符合E-4模型,即由2对等加性主基因+加性-显性多基因共同控制;叶长主基因遗传率为83.80%,多基因遗传率为1.05%;叶宽主基因遗传率为22.28%,多基因遗传率为61.92%。(3)叶形指数和叶缘缺刻数均符合E-1模型,即由2对加性-显性-上位性主基因+加性-显性多基因控制;叶形指数主基因遗传率为93.73%,多基因遗传率为2.59%;叶缘缺刻数主基因决定了表型变异的91.18%。     

稻瘟病菌群体的分子遗传学研究III.——广东省2001年度稻瘟病菌群体的遗传结构分析以及两个假说的提出

利用随机扩增多态性DNA技术(randomamplifiedpolymorphicDNA,RAPD)对广东省2001年度稻瘟病菌群体的遗传结构进行了分析。以相似性系数为0.70阈值时,可将采集于广东省三大生态稻作区、早稻和晚稻生长季节的96个菌株划分为12个遗传宗谱;其中宗谱8和9的菌株数各占总数的25%和18.8%,为优势宗谱。从稻作区来看,宗谱3和8为各个稻作区的共同宗谱;而宗谱1和2,7和11,以及9、10和12则依次是粤北、粤中和粤南稻作区的特异性宗谱。从生长季节来看,来源于早、晚季的菌株完全分属于宗谱图的上、下两个半区,彼此之间不存在共同的宗谱;而且两个优势宗谱都集中于晚季供试亚群体。结合前两次实验的结果,作者提出了如下两个假说来解释广东省稻瘟病菌群体所表现的遗传特性:一个地区或生长季节的病原菌群体,其优势宗谱所占的比例越高,该地区或生长季节病害发生就越严重;在长期的水稻栽培历史中,稻瘟病菌群体可能逐步地形成了早季宗谱(小种)和晚季宗谱(小种)的遗传分化。如何进一步验证上述两个假说是值得我们进一步探讨的重要课题。     

不结球白菜叶子重量性状遗传模型分析

应用主基因+多基因6个世代联合分离分析方法, 对不结球白菜SI×秋017组合的叶片重和叶柄重性状进行了分析。结果表明, SI×秋017组合的叶片重性状遗传受1对负向完全显性主基因+加性-显性多基因(D-4)控制, 主基因加性效应为1.8991, 显性效应为-1.8991; 多基因加性效应为-1.2934, 显性效应为1.7933; 势能比值为-1.3865, 显性度为-1.0000; B1、B2和F2世代群体叶片重的主基因遗传率分别为6.98%、4.33% 和36.08%; B1、B2和F2世代群体叶片重的多基因遗传率为16.03%、7.39%和23.96%。叶柄重的遗传受1对加性主基因+加性-显性多基因(D-2)控制, 主基因加性效应为-1.1457, 显性效应为0; 多基因加性效应为1.3472, 多基因显性效应为2.5788; 势能比值为1.9142, 显性度为0。B1、B2和F2世代群体叶柄重的主基因遗传率分别为31.72%、5.27%和57.94%。B1、B2和F2世代群体叶柄重的多基因遗传率分别为0.42%、4.59%和4.80%。对SI×秋017组合叶片重性状的改良要在晚代选择; 对叶柄重的改良要以主基因为主, 可在早代选择。     

稻瘟病菌群体的分子遗传学研究III.*——广东省2001年度稻瘟病菌群体的遗传结构分析以及两个假说的提出

利用随机扩增多态性DNA技术(randomamplifiedpolymorphicDNA,RAPD)对广东省2001年度稻瘟病菌群体的遗传结构进行了分析。以相似性系数为0.70阈值时,可将采集于广东省三大生态稻作区、早稻和晚稻生长季节的96个菌株划分为12个遗传宗谱;其中宗谱8和9的菌株数各占总数的25%和18.8%,为优势宗谱。从稻作区来看,宗谱3和8为各个稻作区的共同宗谱;而宗谱1和2,7和11,以及9、10和12则依次是粤北、粤中和粤南稻作区的特异性宗谱。从生长季节来看,来源于早、晚季的菌株完全分属于宗谱图的上、下两个半区,彼此之间不存在共同的宗谱;而且两个优势宗谱都集中于晚季供试亚群体。结合前两次实验的结果,作者提出了如下两个假说来解释广东省稻瘟病菌群体所表现的遗传特性:一个地区或生长季节的病原菌群体,其优势宗谱所占的比例越高,该地区或生长季节病害发生就越严重;在长期的水稻栽培历史中,稻瘟病菌群体可能逐步地形成了早季宗谱(小种)和晚季宗谱(小种)的遗传分化。如何进一步验证上述两个假说是值得我们进一步探讨的重要课题。     

稻瘟病菌群体的分子遗传学研究Ⅲ.广东省2001年度稻瘟病菌群体的遗传结构分析以及两个假说的提出

利用随机扩增多态性DNA技术 (random amplified polymorphic DNA, RAPD) 对广东省2001年度稻瘟病菌群体的遗传结构进行了分析.以相似性系数为0.70阈值时,可将采集于广东省三大生态稻作区、早稻和晚稻生长季节的96个菌株划分为12个遗传宗谱; 其中宗谱8和9的菌株数各占总数的25% 和18.8%,为优势宗谱.从稻作区来看,宗谱3 和 8为各个稻作区的共同宗谱;而宗谱1和 2,7和11,以及9、10和12则依次是粤北、粤中和粤南稻作区的特异性宗谱.从生长季节来看,来源于早、晚季的菌株完全分属于宗谱图的上、下两个半区,彼此之间不存在共同的宗谱;而且两个优势宗谱都集中于晚季供试亚群体.结合前两次实验的结果,作者提出了如下两个假说来解释广东省稻瘟病菌群体所表现的遗传特性一个地区或生长季节的病原菌群体,其优势宗谱所占的比例越高,该地区或生长季节病害发生就越严重;在长期的水稻栽培历史中,稻瘟病菌群体可能逐步地形成了早季宗谱(小种)和晚季宗谱(小种)的遗传分化.如何进一步验证上述两个假说是值得我们进一步探讨的重要课题.     

Heterosis studies for yield and its components in bread wheat over environments

A set of diallel crosses involving 10 parents was made to have information on the extent of heterosis over mid-parent and better parent and inbreeding depression for yield and yield contributing characters under three different environments. Marked heterobeltiosis for grain yield and its important components were observed. For grain yield, 83 crosses showed significant positive heterobeltiosis in all the three sowing dates, however, twenty crosses showed significant consistent heterobeltiosis for grain yield per plant over all the three environments. The maximum heterobeltiosis for grain yield per plant observed was 50.94% (Raj 3765 x HD 2285), 121.08% (PBW 373 x HD 2329) and 93.96% (PBW 373 x HD 2329) under early, normal and late sowing conditions, respectively. Cross PBW 373 x HD 2329 in both early and normal plantings and cross Raj 3765 x HD 2285 under late planting were observed most heterotic for grain yield. The crosses showing heterosis for grain yield were not heterotic for all the characters. Heterosis for grain yield per spike followed by tillers per plant and 1000-grain weight was independently associated with heterosis for grain yield in early and normal plantings. However, heterosis for grain yield per spike, dwarf plant height and tillers per plant contributed maximum towards yield heterosis. Significant inbreeding depression was recorded frequently for yield and yield contributing traits, however, in a few traits it was observed significant negative indicated that F(2) was superior to F(1) considered desirable combination for trait(s). The study reveals good scope for commercial exploitation of heterosis as well as isolation of pure lines among the progenies of heterotic F(1) for improvement of yield levels in bread wheat.     

杂交水稻及其亲本光合特性的研究Ⅱ.功能叶片的希尔反应、光合磷酸化、ATP酶活性和ATP含量

研究了杂交水稻青优159（母本青A,父本R159）和广优四号（母本广A,父本青六矮）及其亲本功能叶片的希尔反应活性、光合磷酸化、ATP含量及ATP酶活性等。实验结果表明了两组杂交水稻功能叶片的希尔反应活性高于其亲本,其超亲优势分别为13．44％、13、93％,平均优势分别为26．44％、1774％;功能叶片的光合磷酸化活性亦有杂种优势,其超亲优势分别为21．35％、18．81％,平均优势分别为34．06％、22．71％;杂种F1的两种ATP酶（Cd －ATP酶和Mg －ATP酶）活性和叶组织中ATP含量均高于其亲本,亦表现出明显的杂种优势。另外从我们的试验结果中还可以见到,希尔反应活性、光合磷酸化活性、ATP酶活性及ATP含量与光合速率的大小有密切的正相关关系,说明这些生理生化特性可以作为高光合速率杂交水稻鉴别的指标。     

Effects of high temperature during grain filling under control conditions on the physicochemical properties of waxy maize flour

The effects of high temperature during different grain filling stages (1–15 d and 16–30 d after pollination) on the physicochemical properties of four varieties of waxy maize grain were studied. Heat stress during grain filling decreased grain weight and starch deposition, while it increased protein content, starch granule size, abnormal granule numbers and iodine binding capacity. These effects were more severe when heat stress was introduced at early development stage than at late grain filling stage. The peak intensities and crystallinities were decreased when plants were exposed to high temperature at early development stage. By contrast, responses to high temperature at late development stage were variety-dependent. High temperature during grain filling decreased the peak and breakdown viscosities and increased the gelatinization temperature and enthalpy, and retrogradation percentage of flours, especially during early development stage. In conclusion, high temperature during grain filling changed the grain proximate and starch structure, resulting in the deterioration of pasting and thermal properties.     

籼稻糙米厚度的发育遗传研究

应用包括３套遗传体系基因效应的数量性状发育遗传模型,分析了１２个籼稻亲本在４个不同稻米发育时期的糙米厚性状。结果表明,三倍体胚乳、二倍体母体植株基因的加性和显性效应以及细胞质效应均可以明显影响各个稻米发育时期的糙米厚度,其中灌浆始期以二倍体母体植株效应为主,灌浆中后期以三倍体胚乳效应为主,成熟期则以细胞质效应为主。在４个不同发育时期中,控制糙米厚的基因加性效应和显性效应交替为主。胚乳显性方差和母体     

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.     

Overdominant epistatic loci are the primary genetic basis of inbreeding depression and heterosis in rice. I. Biomass and grain yield

To understand the genetic basis of inbreeding depression and heterosis in rice, main-effect and epistatic QTL associated with inbreeding depression and heterosis for grain yield and biomass in five related rice mapping populations were investigated using a complete RFLP linkage map of 182 markers, replicated phenotyping experiments, and the mixed model approach. The mapping populations included 254 F(10) recombinant inbred lines derived from a cross between Lemont (japonica) and Teqing (indica) and two BC and two testcross hybrid populations derived from crosses between the RILs and their parents plus two testers (Zhong 413 and IR64). For both BY and GY, there was significant inbreeding depression detected in the RI population and a high level of heterosis in each of the BC and testcross hybrid populations. The mean performance of the BC or testcross hybrids was largely determined by their heterosis measurements. The hybrid breakdown (part of inbreeding depression) values of individual RILs were negatively associated with the heterosis measurements of their BC or testcross hybrids, indicating the partial genetic overlap of genes causing hybrid breakdown and heterosis in rice. A large number of epistatic QTL pairs and a few main-effect QTL were identified, which were responsible for >65% of the phenotypic variation of BY and GY in each of the populations with the former explaining a much greater portion of the variation. Two conclusions concerning the loci associated with inbreeding depression and heterosis in rice were reached from our results. First, most QTL associated with inbreeding depression and heterosis in rice appeared to be involved in epistasis. Second, most ( approximately 90%) QTL contributing to heterosis appeared to be overdominant. These observations tend to implicate epistasis and overdominance, rather than dominance, as the major genetic basis of heterosis in rice. The implications of our results in rice evolution and improvement are discussed.     

Studies of heterosis,combining ability and inheritance of yield and yield components in a diallel cross of bengal gram (Cicer arietinum L.)

Summary A 5 X 5 diallel cross among well-adapted varieties of gram from different agroclimatic regions was studied for heterosis, combining ability and inheritance of days-to-flowering, primary branches, pods per plant, 100-seed weight and grain yield. A high degree of heterosis over mid-parent and better parent was observed for primary branches, no. of pods and grain yield, whereas very little heterosis was exhibited for days-to-flower and 100-seed weight. Crosses among lines of diverse origin generally gave higher heterosis and over-dominance than lines from the same region. Primary branch number, pod number, and grain yield exhibited positive over-dominance; days-to-flower showed negative over-dominance while 100-seed weight had no dominance. Both general and specific combining ability effects were significant for all the characters studied but g.c.a. effects appeared to be more important for days-to-flower, 100-seed weight and grain yield. Graphical analysis indicated additive effects for all the characters, with complete dominance for days-to-flower, no dominance for 100-seed weight and over-dominance for the other three characters. Dominant genes conditioned earliness, primary branch number and 100-seed weight. The role of various parents and crosses in planning a hybridization programme has been discussed.     

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.     

Genetic Components of Heterosis for Seedling Traits in an Elite Rice Hybrid Analyzed Using an Immortalized F_2 Population

Utilization of heterosis has greatly contributed to rice productivity in China and many Asian countries. Superior hybrids usually show heterosis at two stages: canopy development at vegetative stage and panicle development at reproductive stage resulting in heterosis in yield. Although the genetic basis of heterosis in rice has been extensively investigated, all the previous studies focused on yield traits at maturity stage. In this study, we analyzed the genetic basis of heterosis at seedling stage making use of an "immortalized F2" population composed of 105 hybrids produced by intercrossing recombinant inbred lines(RILs) from a cross between Zhenshan 97 and Minghui 63,the parents of Shanyou 63, which is an elite hybrid widely grown in China. Eight seedling traits, seedling height, tiller number, leaf number, root number, maximum root length, root dry weight, shoot dry weight and total dry weight, were investigated using hydroponic culture. We analyzed single-locus and digenic genetic effects at the whole genome level using an ultrahigh-density SNP bin map obtained by population re-sequencing. The analysis revealed large numbers of heterotic effects for seedling traits including dominance, overdominance and digenic dominance(epistasis) in both positive and negative directions. Overdominance effects were prevalent for all the traits, and digenic dominance effects also accounted for a large portion of the genetic effects. The results suggested that cumulative small advantages of the single-locus effects and two-locus interactions, most of which could not be detected statistically, could explain the genetic basis of seedling heterosis of the F_1 hybrid.