Genetic and Correlation Analysis of Grain Characters in Three-line Hybrid Rice

Abst[Objective] This study was to understand the genetic dynamics of three-line hybrid rice, and explore the respective effect of sterile line and restoring line on grain characters of hybrid rica. [Method] Four three-line stedle lines and 27 restoring lines（cultivars） commonly culti- vated in Central China region were regarded as expadmental materials to conduct 4 x27NCII cross design, and the grain characters of three-line hybrid rico were analyzed at genetic and correlation levels. [ Result] Four characters of grain length, grain width, 1 000-grain weight and length- width ratio play the leading role in additive gene effect; these four characters were simultaneously influenced by male parent and female parent, but the effect from male parent was relatively larger. The grain length, grain width, 1 000-grain weight and length-width ratio all have high brood hedtabUities（ respectively 99.65%, 98.31%, 95.27% and 98.81% ）. Correlation analysis showed that grain length was positively correlated with 1 000-grain weight and length-width ratio at extremely significant level; 1 000-grain weight was positively correlated with grain length and length- width ratio at extremely significant level, and was insignificantly correlated with grain width; grain width was negatively correlated with grain length and length-width ratio at extremely significant level. Path analysis showed that the direct path coefficients of grain length, grain width and 1 0（30- grain weight to length-width ratio were 0.624 6, -0.555 9 and -0.015 8, respectively. [ Conclusion] This study systematically analyzed the effects of stedle line and restoring line on grain characters of hybrid rice, which provided theoretical basis for breeding high quality and yield hy- brid dce.

Technical Specification for Producing Hybrid Pepper Seed Using Three-line Male Sterility

This paper described the whole process of three line hybrid pepper seed production in detail, including requirement of the seed production base, parent culti- vation, field management, and specified the key operation techniques in seed pro- duction, such as parental impurity removal to preserve pure state, pollen collection, pollination and seed collecting essentials. This specification is of guiding significance for the production of hybrid pepper seed and ensuring the purity of hybrid pepper seed.

Transcriptomic and metabolomic analysis provides insights into lignin biosynthesis and accumulation and differences in lodging resistance in hybrid wheat

The use of hybrid wheat is one way to improve the yield in the future.However,greater plant heights increase lodging risk to some extent.In this study,two hybrid combinations with differences in lodging resistance were used to analyze the stem-related traits during the filling stage,and to investigate the mechanism of the difference in lodging resistance by analyzing lignin synthesis of the basal second internode(BSI).The stem-related traits such as the breaking strength,stem pole substantial degree(SPSD),and rind penetration strength(RPS),as well as the lignin content of the lodging-resistant combination(LRC),were significantly higher than those of the lodgingsensitive combination(LSC).The phenylpropanoid biosynthesis pathway was significantly and simultaneously enriched according to the transcriptomics and metabolomics analysis at the later filling stage.A total of 35 critical regulatory genes involved in the phenylpropanoid pathway were identified.Moreover,42%of the identified genes were significantly and differentially expressed at the later grain-filling stage between the two combinations,among which more than 80%were strongly up-regulated at that stage in the LRC compared with LSC.On the contrary,the LRC displayed lower contents of lignin intermediate metabolites than the LSC.These results suggested that the key to the lodging resistance formation of LRC is largely the higher lignin synthesis at the later grain-filling stage.Finally,breeding strategies for synergistically improving plant height and lodging resistance of hybrid wheat were put forward by comparing the LRC with the conventional wheat applied in large areas.

Studies on the Developmental Genetics of Tiller Number in Three-line Indica Hybrid Rice

Following NCI design, the developmental genetic behavior of tiller number (TN) in three-line indica hybrid rice was studied using additive-dominance developmental genetic models and the corresponding statistical methods. The results showed that dominance effects were predominant for TN. The expression of those additive effects were affected by environment and genotype interaction, but the expression of dominance effects were not affected. Heterosis was the strongest in the middle developmental periods of TN. Additive effects and dominance effects were selectively expressed throughout in the entire tillering developmental stage. Analysis of genetic correlation between TN at different stages and the productive panicles indicated that a close correlation appeared earlier in the populations with higher heterosis than in those with less heterosis. Utilization of heterosis at the middle tillering stage might enhance the final biomass but reduce the percentage of productive panicles.

Research and Breeding Application Progress of the Technique of Producing Double Haploid of Wheat by Wide Hybridization between Wheat and Maize

The technique of producing doublehaploid of wheat by distant hybridization between wheat and maize has characterized with better inducing effect, shorter in- ducing period, easy operation, and so on. At present, it is the most efficient and has great potential of application in breeding of wheat. This article reviewed princi- ple and production process of the technique, research situation of the three key in- dicators of the technology（embryo rate, seedling rate and success rate of doubling）in recent years, and application of the technology in breeding, genetics, germplasm improvement of wheat. At last, both the achievements and the direction of further improvement and development of the technology in our program were discussed.

Cytogenetical Analysis of Hybrid F1 from Common Wheat and Aegilops ventricosa × Aegilops cylindrica Amphidiploid

[Objective] The aim of this study is to investigate the chromosome pairing of F1 from Aegilops Ventricosa-Aegilops Cylindrica amphiploid × common wheat.[Method] Microsporogenesis and pollen development of Yannong15,SDAU18 and their hybrid F1 were observed cytologically by squash method.[Result] The results showed that microsporogenesis and pollen development of two parents including Yannong15 and SDAU18 were basically normal,and their seed setting was also basically normal.However,the microsporogenesis of their hybrid F1 was chaotic.Univalent and bivalent with high frequency of 10.11 and 18.29 per cell respectively occurred in meiotic MI（metphaseI） of PMC（pollen mother cell）.Nevertheless,only quite low frequency of multivalents occurred in meiotic PMC MI.The laggards at meiotic AI（anaphaseI） were 5 per cell on average.The number of micronucleoli in tetrad was 4.43 per cell averagely.The aborted pollen with different frequency occurred at every stage of hybrid F1 pollen development but mainly after single nucleus pollen stage.The fertile pollen rate of hybrid F1 was only 31% at 3-nucleated stage.[Conclusion] This study provides cytogenetics basis for further analysis and utilization of the amphiploid.

Breeding and Cultivation Technique of Recessive Genic Male Sterility Hybrid Wheat New Variety Xinan 112

Xinan 112 is the hybrid combination（11S12） by wheat recessive genic male sterility line 2011Z1 （08L5070） and restoring line K152-2, particpating in the regional test of 2011-2012, 2012-2013 and production test of 2013-2014 in Chongqing. The results showed that 3 years average yield was 4 167.5 kg/hm2, which was increased 10.5% compared with CK Yumai 7, 1 000-grain weight was 45.8 g, which was 1.7 g heavier than the control; grain number per ear was 39.3, more than 1.6 grains compared with CK. The results of 2 years quality determination were： bulk density of 811 g/L, falling number of 353 s, crude protein of 15.15%, wet gluten of 31.2%, water adsorption of 62.9 ml/100 g, formation time of 5.5 min, stable time of 6.5 min, softening degree of 90 F.U., and powder quality coefficient of 96 mm. Therefore, Xinan 112 is a high yield and high protein gluten wheat variety and is suitable for cultivated in Chongqing and climate contion similar areas.

The contribution of distant hybridization with decaploid Agropyron elongatum to wheat improvement in China

Wheat is a staple food crop in the world as well as in China. Because of the progress of wheat breeding and other agricultural ＂sci-technologies, the wheat grain yield per unit area has increased more than five folds from 1952 to 2006 in China. The first part of this article briefly reviews the history of wheat breeding in China. Second, the establishment of ＂Triticum aestivum-Agropyron＂ distant hybridization system and its contribution to wheat production and breeding in China are summarized. Finally, the future challenges of wheat breeding are discussed, which include how to increase the utilization efficiencies of water, soil nutrient and light energy through breeding. As an example, our research progress on how to increase light use efficiency in wheat through breeding is introduced and discussed.

Programmed cell death, antioxidant response and oxidative stress in wheat f lag leaves induced by chemical hybridization agent SQ-1

Male sterility induced by a chemical hybridization agent （CHA） is an important tool for utilizing crop heterosis. Leaves, especially the flag leaves, as CHA initial recipients play a decisive role in inducing male sterility. To investigate effects of different treatment times of CHA-SQ-1 used, morphological, biochemical and physiological responses of wheat flag leaves were detected in thistudy. CHA induced programmed cell death （PCD） as shown in terminal deoxynucleotidyl transferase-mediated dUTP nick end-labelling （TUNEL） and DNA laddering analysis. In the early phase, CHA-SQ-1 trig- gered organelle changes arid PCD in wheat leaves accompanied by excess production of reactive oxygen species （O2- and H202） and down-regulation of the activities of superoxide dismutase （SOD）, catalase （CAT） and guaiacol peroxidase （POD）. Meanwhile, leaf cell DNAs showed ladder-like patterns on agarose gel, indicating that CHA-SQ-1 led to the activation of the responsible endonuclease. The oxidative stress assays showed that lipid peroxidation was strongly activated and photosynthesis was obviously inhibited in SQ-l-induced leaves. However, CHA contents in wheat leaves gradually reduced along with the time CHA-SQ-1 applied. Young flags returned to an oxidative/antioxidative balance and ultimately developed into mature green leaves. These results provide explanation of the relations between PCD and anther abortion and practical application of CHA for hybrid breeding.

The Growth Analysis in the Kernel Filling Process of K-Type Hybrid 901 and Its Parent Wheat

Using Matlab software, the grain filling process of hybrid wheat 901 and its parents was fitted by Richards equation W = A/（1 ＋ Be^-kt in order to study the characteristics of grain filling of the hybrid. The active grain growth period of the hybrid was 6 d longer than that of Shaan 229, and its final grain weight （43.7 g/1 000 grains） was higher than that of Shaan229 （36.3 g/1 000 grains）. N values of 901 and R205 were both less than 1, and their grain growth was faster in the early filling stage, while slower in the middle-late stage. N value of Shaan 229 was 〉1~ and its growth was slower in the early stage and faster in the middle stage. The period of early stage of 901 was shorter and of middle-late stage was longer. The situation of Shaan 229 was totally reversed. For parents, the father plant R205 was similar to hybrid wheat 901, whereas its mother plant K3314A similar to Shaan 229. It has been found that Richards equation was more suitable for fitting the grain filling process of wheat than Logistic equation.

Grain Sink Strength Related to Carbon Staying in the Leaves of Hybrid Wheat XN901

XN901 is a K-type three-line hybrid wheat with a high yield potential, and its leaves and stem remaining green during grain maturation, suggesting much assimilate stay in leaves and stem. The grain water content, grain volume, carbohydrate content, and enzyme activity of sucose metabolism in the grain, as well as source-sink relationship were studied in order to investigate the physiological reason of the assimilate remaining in leaves and stem at the late stage. The results showed that the hybrid grains had more water and soluble sugar, higher activities of acid invertase and sucrose synthase at the early stage that led to a faster expansion growth, greater grain volume and faster starch synthesis at the early to mid stage of grain development. Also it had a longer period for actively filling. As a result, the grain weight and yield of the hybrid were increased by 14 and 15% respectively compared to that of Shaan 229. Additionally, the biomass of XN901 was 41.7% more than that of control, but its harvest index was 9% lower than Shaan 229. However, its lower activity of sucrose synthase indicated a lower sink activity at the late stage, resulting in a slow rate of filling and starch synthesis. Also, the hybrid wheat XN901 had a large source-sink ratio. It is the main reason for much assimilate remaining in the straw at the late stage and lower harvest index. Strengthening the sink activity and raising the harvest index should be the key means of improving the yield of hybrid wheat.

Research and application of hybrid wheat in China

Hybrid wheat is recognized as a preferred approach to improve wheat yield,and it will be a competition focus in high-tech seed industry in the future. We have made a breakthrough for the first time in creation of two-line hybrid wheat system,which reaches the world leading level in wheat research and has laid an important foundation for the future direction of the world wheat research. Similar to hybrid rice,the innovation of two-line hybrid wheat system is another achievement in science and technology. The application of hybrid wheat in China will greatly increase the food production,and make a great significance to food production and food security. This paper introduces the development process and major breakthrough of hybrid wheat in China,and the main bottleneck and countermeasures in the application of hybrid wheat.

Yield-related agronomic traits evaluation for hybrid wheat and relations of ethylene and polyamines biosynthesis to filling at the mid-grain filling stage

Because of the yield increase of 3.5-15%compared to conventional wheat,hybrid wheat is considered to be one of the main ways to greatly improve the wheat yield in the future.In this study,we performed a principal component analysis(PCA)on two-line hybrids wheat and their parents using the grain weight(GW),the length of spike(LS),the kernel number of spike(KSN),and spike number(SPN)as variables.The results showed that the variables could be classifed into three main factors,the weight factor(factor 1),the quantity factor 1(factor 2)and the quantity factor 2(factor 3),which accounted for 37.1,22.6 and 18.5%,respectively of the total variance in different agronomic variables,suggesting that the GW is an important indicator for evaluating hybrid combinations,and the grain weight of restorer line(RGW)could be used as a reference for parents selection.The hybrid combination with a higher score in factor 1 direction and larger mid-parent heterosis(MPH)of the GW and its parents were used to carry out the analysis of grain fling,1-aminocylopropane-1-carboxylicacid(ACC)and polyamine synthesis related genes.The results suggested that the GW of superior grain was significantly higher than that of inferior grains in BS1453xJS1(H)and its parents.Both grain types showed a weight of H between BS 1453(M)and JS1(R),and a larger MPH,which may be caused by their differences in the active fling stage and the grain fling rate.The ADP-glucose pyrophosphorylase(AGPase),granule bound starch synthase I(GBSS/),starch synthaseⅡ(SSS),and starch branching enzyme-Ⅰ(SBE-1)expression levels of H were intermediated between M and R,which might be closely related to MPH formation of the GW.Compared with R and H,the GW of M at maturity was the lowest.The expression levels of spermidine synthase 2(Spd2),ornithine decarboxylase(ODC)and S adenosylmethionine decarboxylase(SAMDC)had significantly positive correlations with the grain flig rate(1=0.77,0.51,0.59"),suggesting their major roles in the grain flling and heterosis formation.These provide a theoretical basis for improving the GW of photo-thermo-sensitive male sterile lines(PTSMSL)by changing the endogenous polyamine synthesis in commercial applications.

Effects of Different Row Ratios of Male and Female Parents and Application Amount of Nitrogen Fertilizer on Hybrid Wheat Seed Production and Its Component Factors

In order to screen suitable high hybrid wheat seed production technology,the split-plot experiment design was adopted and study was carried out about the effects of the different row ratios of male and female parents and application amount of nitrogen fertilizer on hybrid wheat seed production and its component factors. The results showed that the seed production increased with the increase in the number of female parent row. When the row ratio of male and female parents was 2 ∶ 6,the seed production was 3 683. 8 kg/ha; when the application amount of nitrogen fertilization was 50 kg/ha,the seed production was 3 649. 4 kg/ha; the interaction between the row ratio of male and female parents and the application amount of nitrogen fertilizer indicated that when the row ratio of male and female parents was 2∶ 6 and the application amount of nitrogen fertilizer was 300 kg/ha,the seed production reached the highest( 4160. 6 kg/ha). The row ratio of male and female parents and application amount of nitrogen fertilizer had significant effect on the component factors of seed production,including the number of grains per spike,spike weight and setting percentage. When the row ratio of male and female parents was 2∶ 5,the number of grains per spike,spike weight and setting percentage were the highest at 26. 7 grains,1. 12 g,and 62. 6% respectively; when application amount of nitrogen fertilizer was 450 kg/ha,the number of grains per spike,spike weight and setting percentage were the highest at 26. 0 grains,1. 08 g,and59. 2% respectively; the interaction of row ratio of male and female parents and application amount of nitrogen fertilizer had significant effect on the number of grains per spike,spike weight and setting percentage; when the row ratio of male and female parents was 2∶ 5 and the application amount of nitrogen fertilizer was 300 kg/ha,the number of grains per spike,spike weight and setting percentage were the highest at 29. 6grains,1. 24 g,and 71. 6% respectively. The number of grains per spike is the largest component factor for seed production. Increasing the number of grains per spike can increase the seed production. According to the effects of row ratio of male and female parents and application amount of nitrogen fertilizer on the component factors of seed production,the optimal condition was 2∶ 5-2∶ 6 for row ratio of male and female parents and 300-450 kg/ha for application amount of nitrogen fertilizer.

Comparative Proteomic Analysis of Wheat (Triticum aestivum L.) Hybrid Necrosis

Hybrid necrosis is the gradual premature death of leaves or plants in certain Fj hybrids of wheat （Triticum aestivum L.）. Comparison of protein expression in necrotic and normal wheat leaves showed that the abundance of 33 proteins was changed significantly, and 24 of these proteins were identified. These proteins were involved in plant growth and development, antioxidation, photosynthesis and carbon assimilation, amino acid and protein biosynthesis, cytological signal transduction, DNA and RNA modification, protein transport, folding and assembly according to their functions. The down-regulation of uroporphyrinogen decarboxylase and the up-regulation of lipoxygenases in necrotic leaves may be related to the oxidative stress in the necrotic cells. The heat shock proteins may play the cytoprotective role. The differential expression of photosynthesis and carbon assimilation related proteins indicated chlorophyll biosynthesis and chloroplast development were inhibited and might finally cause the gradual chlorosis and cell death in necrotic leaves. The results of this study give a comprehensive picture of the post-transcriptional response to necrosis in hybrid wheat leaves and serve as a platform for further characterization of gene function and regulation in wheat hybrid necrosis.

Studies on the Utilization Potentiality of the Nucleo-Cytoplasmic Hybrid in Wheat

A series of comparative studies was carried out on the genetic effects of 25 alien cytoplasms of wheat on the growth potential, heading stage, fertility, resistance against diseases, important agronomic traits and its heterosis of 125 nuclei-cytoplasmic hybrids of wheat. The results indicated that there were clearly effects of alien cytoplasms on some characteristics, but the nucleus still exerted main effect on other characteristics. The effect of interactions between nucleus and cytoplasm was comparative obvious in some combination. Consequently, when we utilize the effects of alien cytoplasms, we should pay full attention to the facts such as the characteristic to be improved, the effects of cytoplasm, nucleus, the nucleus-cytoplasm interactions on that characteristics. From the preliminary studies, we believed that the cytoplasmic types of M0, S1, Sv, D2, D and B, and the nucleo-cytoplasmic hybrids of (Ae. sharonensis)-B174, (Ae. squarrosa)-352-35 (Ae. cylindrica)-352-35, (Ae. cylindria)-E EN-1, (Ae. cylindrica)-NPFP, and (Ae. speltoides)-352-35 would have some utilization potentiality in cultivar improvement.

Influences of Root Zone Restriction and Nitrogen Nutrition on Hybrid Wheat Growth

To study the physiological effects of small root zonel plants of a hybrid wheat variety (Triticum aestivnmL.cv. Meiyou 4) were grown in small pots (1 litre) or large pots (8 litre) with 1ow nitrogen (50 mg kg-1 soil)and high nitrogen (200 mg kg-1 soil). Restricting root zone decreased dry weight of plants at the stages ofstem elongation and flowering, compared to those of control plants grown in the large pots (P<0.01). Sprayingof 6-benzylaminopurine (50 μmol L-1) increased dry weight of plants and chlorop hyll concentration in leaves.Restriction of root zone decreased the concentrations of total nitrogen, chlorophyll and soluble protein in thefiag leaf and acce1erated senescence of the leaves. Supply of high nitrogen delayed senescence of the fiag leafThe results suggested that the shortage of nutrients, especially nitrogen deficiency was the primary reasonfor the decreased growth of plant in the treatment of root zone restriction.

An Alternative Analysis on Nilsson-Ehle’s Hybridization Experiment in Wheat —Theory of Dual Multiple Factors and Three Normal Distributions on Quantitative Inheritance (Continuation)

In this paper, an analysis on Nilsson-Ehle’s hybridization experiment in wheat was done by means of self-fertilization method along with the pericarp inheritance. It showed that because seeds of wheat were coated with 2n tissues of mother’s body, the grain colors were determined by mother’s genotype. The color of the F1 grains in this experiment was old red. The phenotypes of the F2 grains were uniformly medium red and did not segregate. Grains in the F3 generation segregated in the ratio 6 red (varying intensities of red) to 1 white with a definite probability respectively. This is the consequence of additive effect of 3 gene pairs and belongs to discrete distribution rather than continuous distribution. Therefore, the multiple-gene hypothesis based on this experiment cannot solve the continuous variations in inheritance of quantitative characters.

Synthesis of a Wheat/Maize Hybrid CENH3 Gene, the Genetic Transformation of Wheat, Its Chromosomal Localization and Effects on Chromosome Behaviors in Wheat/Maize Somatic Hybrids

Centromere-specific histone H3 (CENH3) replaces the canonical histone H3 in nucleosomes of functional centromeres, and plays important roles in faithful chromosome segregation during cell division. CENH3 is also important in the recognition of alien centromeres and determines the accommodation or elimination of alien chromosomes in interspecific or intergenic hybridization. In this study, a maize full length CENH3 with a yellow fluorescent protein (YFP) tag at C-terminus (ZmCENH3-YFP) and a synthetic hybrid wmCENH3 with the N-terminus from wheat CENH3 and the histone fold domain (HFD) from maize tagged with a red fluorescent protein (RFP) at the C-terminus (wmCENH3-RFP) were transformed to wheat by biolistics transformation. Transgenic wheat plants with both ZmCNEH3-YFP and wmCENH3-RFP genes were identified by PCR. The expression of ZmCENH3-YFP was not observed, while the expression of wmCENH3-RFP could be detected by RT-PCR, direct fluorescence microscopy, and immunostaining with anti-RFP antibody. The expressed wmCENH3-RFP was localized to nuclei as dotted patterns, indicating its targeting to wheat centromeres. Somatic hybridization was performed between wmCENH3-RFP transgenic wheat and transgenic maize that expressed a ZmCENH3-YFP gene to investigate chromosome behaviors in somatic hybrids. Cytological and FISH analyses of somatic hybrid cells showed the formation of micronuclei and lagging chromatin in both somatic hybridizations with or without the wmCENH3-RFP transgene, indicating that ectopically expressed wmCENH3 could not overcome chromosome elimination in wheat/maize somatic hybrids. Immunostaining of wmCENH3-RFP and ZmCENH3-YFP in early stage somatic hybrid cells indicated that both wmCENH3-RFP and ZmCENH3-YFP proteins were expressed, but their binding patterns changed from the commonly observed dotted patterns to diffused ones, suggesting that the inactivation of CENH3 might be a factor for chromosome elimination in wheat/maize somatic hybridization.

Using Subtracted AFLP to Efficiently Mark an Alien Chromosome Fragment in Wheat Background

为解决AFLP中样品间共同片段对多态性片段识别的干扰 ,作者建立了一种“减法AFLP”标记技术 ,并运用这种技术成功对小麦中的外源染色体片段进行了标记。运用该技术 ,样品间的共同扩增片段显著减少 ,在非变性聚丙稀酰胺凝胶上带型差异十分明显 ,多态性片段很容易分辨。其真实性通过将其中两条成功转换成外源染色体片段特异的SCAR标记得到了验证。减法AFLP标记技术的建立为标记作物中的外源染色体片段提供了一种有效手段。