矮秆基因对小麦部分农艺性状的效应

以中国主要麦区的124份小麦品种为材料,利用分子标记和系谱分析相结合,对其按照所含的矮秆基因Rht-B1b、Rht-D1b和Rht8进行分类,结合田间株高、旗叶长、小穗数和穗粒数以及室内苗期根系长度等农艺形状的调查,分析不同矮秆基因对小麦农艺性状的效应.结果显示:(1)参试的124份小麦品种(系)中23份含有Rht-B1b,7份含有Rht-D1b,22份含有Rht8基因,34份同时含有Rht-B1b和Rht8,16份同时含有Rht-D1b和Rht8,可分为6组.(2)Rht-B1b和Rht-D1b在降低株高的同时也缩短了旗叶的长度和苗期叶长,Rht8对株高的影响较弱,对旗叶和苗期叶长的影响也较小;3个矮秆基因对苗期根系长度、小穗数没有显著影响;Rht-D1b和Rht8显著增加穗粒数.研究表明,矮秆基因Rht8对小麦株高以及其他农艺性状的影响均较小,但能够显著增加穗粒数,是小麦矮化育种中比较理想的矮秆基因.     

Relevance of physiological efficiency in wheat grain quality and the prospects of improvement

Released and pre-released bread wheat varieties evaluated in national wheat programme of India (503 genotypes) during 2005–14 under different environments were examined for the role of physiological parameters in grain quality. Genotypes with slow plant height growth but faster rate of grain filling enhanced protein content. Plants where growth in height and grain development was slow, grains were hard, provided proportionate vegetative growth phase is longer. Steady grain growth rate benefited gluten strength and gluten quality. Irrespective of total crop duration, longer reproductive phase was an effective indicator of higher flour recovery and test weight. Magnitude and significance of morphological attributes in grain quality was almost similar to that of physiological processes, therefore prospects of utilizing these field traits were examined to enhance grain properties. Early heading and longer grain filling was effective to increase test weight whereas delayed heading and shorter plant height enhanced protein content. Bold grains hampered grain hardness and delayed heading added more bran in the flour. Genotypes with poor grain bearing and quick grain ripening had lower sedimentation value. Instead of protein, it was wet gluten which expressed negative association with yield. To improvise gluten quality, extended reproductive phase but with less grain weight was helpful. Contribution of longer post-anthesis period was observed crucial in flour recovery. These useful simple field expressions can be deployed to uplift quality of wheat grains.     

冬小麦产量性状的遗传效应分析

以农大139等7个冬小麦品种进行4×3不完全双列杂交,采用加性-显性及其与环境互作的遗传模型对亲本、F_1和F_2的株高、主穗穗长、单株穗数、主穗小穗数、千粒重和单株粒重6个性状进行遗传分析．结果表明,株高和主穗长主要受加性效应控制,而单株穗数、主穗小穗数、千粒重和单株粒重主要受显性×环境互作效应影响．矮2杂交后代易选到矮株,奥里生杂交后代易得到大穗材料,农林10号和奥里生的杂交后代分蘖力将加强,814的杂交后代小穗数增多,814杂交后代千粒重增高．所有产量性状未表现明显的杂种优势．     

青海育成小麦5个主效矮秆基因的分子检测

为系统了解青海小麦矮秆基因的分布特点,并进一步为青海高原小麦的株高育种提供优异种质资源。本研究利用5个矮秆基因的特异性分子标记对82份青海小麦品种资源中的矮秆基因进行了检测,并对不同矮秆基因的降秆效应进行了分析。结果表明:82份青海育成小麦品种中有49份材料至少含有一个矮秆基因,其中Rht-B1b的分布频率最高,约占参试材料的28.0%,其次是分布频率为23.2%的Rht8基因,而矮秆基因Rht-D1b、Rht5以及Rht12的分布频率分别为9.8%、13.4%、9.8%。在49份含有不同种类矮秆基因的材料中,其中16份材料同时含有2种及以上的矮秆基因,即RhtB1b和Rht8、Rht-D1b和Rht8、Rht-B1b和Rht5、Rht-D1b和Rht5、Rht8和Rht5、Rht-B1b和Rht12、Rht5和Rht12,并未发现同时含有矮秆基因Rht-B1b和Rht-D1b的品种;2份材料分别含有3种矮秆基因,即Rht-B1b、Rht8、Rht12和Rht-B1b、Rht5、Rht8;其余31份材料仅含有1种矮秆基因。82份青海育成小麦材料中仅含有Rht-B1b的材料11份,平均株高为86.2 cm,其降秆效应为5.7%;只含有Rht-D1b的材料有5份,平均株高为84.9 cm,其降秆效应为7.1%;仅含有Rht8的材料有9份,平均株高为88.6 cm,其降秆效应为3.1%。因此,在青海育成小麦品种中,矮秆基因的降秆效应为Rht-D1bRht-B1bRht8。     

Peroxidase activity in Linum usitatissimum L.

Summary Crosses were made, in all combinations, between 2 parental genotypes of Linum and their reciprocal F ₁ hybrids. The parents and progeny obtained were grown in controlled environmental conditions and sampled at 35 and 70 days after germination to determine, on an individual plant basis, total plant fresh weight and peroxidase activity of main stem tissue. Peroxidase activity required transformation to a log₁₀ scale, whereas the original linear scale was satisfactory for plant weight. There was no correlation between plant weight and corresponding peroxidase activity. Pronounced heterosis appeared in the F ₁'s for both characters at sample 1, but this heterosis had declined at sample 2 and in the F ₂'s. Heterosis operated in a positive direction for plant weight and in a negative direction for peroxidase activity. No consistent differences were found amongst the variances of segregating or non-segregating generations for either character.     

9个小麦品种(系)比较试验中的主要农艺性状

目的:通过对9个小麦品种(系)的比较试验中的主要农艺性状统计分析,筛选出比较适宜现阶段在贵阳地区乃至贵州省栽培的高产优质小麦品种(系)。方法:9个小麦品种(系)在试验地里随机区组排列,3次重复,记录小麦的全生育期,出苗数,田间生育期,株高,有效分蘖数,每株干重,穗长,穗粒重等,并在Excell上进行统计分析。结果:全生育期在200天左右,出苗数有3个超过100万/ha,最低只有44．8万/ha,株高在50 cm以上的有6个品种(系),3个在40 cm-50 cm之间,有效分蘖数400万/ha以上的有3个,最低的是199．1万/ha,每株干重最高是8．5 g,最低是5．7 g,穗长整齐度除98-22外都优于对照,经LSR法测验表明,贵农15,黔98353,黔麦15分别与夏繁29,98-28,贵单5号,黔98284-82,黔0110都达到差异显著水平,贵农15,黔98353,黔麦15分别与98-22达到差异极显著水平,其余的差异皆不明显。结论:可以初步得出贵农15,黔98353,黔麦15目前可以作为在贵阳地区推广种植的较优品种(系)。     

Characterization of a Putative New Semi-Dominant Reduced Height Gene,Rht_NM9, in Wheat(Triticum aestivum L.)

Plant height is an important agronomic trait in cereal crops, and can affect both plant architecture and grain yield. New dwarfing genes are required for improving the genetic diversity of wheat. In this study, a novel dwarf mutant, NM9, was created by treating seeds of the wheat variety NAU9918 with ethyl methanesulfonate(EMS). NM9 showed obvious phenotypic changes, which were distinct from those caused by other dwarfing genes, especially the reduced plant height, increased effective tiller number, and elongated spike and grain length. The reduced plant height in NM9 was attributable to a semi-dominant dwarfing gene Rht_NM9, which was flanked by two closely linked SNP markers, SNP34 and SNP41, covering an 8.86-Mb region on the chromosome arm 2AS. The results of gibberellic acid(GA) sensitivity evaluation, comparative genomics analysis and allelism test indicated that Rht_NM9 was neither allelic to Rht7 and Rht21 nor homoeoallelic to Rht8, so Rht_NM9 was proposed to be a new dwarfing locus on the homoeologous group 2 chromosomes of wheat. Rht_NM9has a negative effect on plant height and positive effects on effective tiller number and grain size, thus, Rht_NM9 could be used for elucidating the mechanisms underlying plant architecture and grain development.     

60Co-γ射线诱变连麦2号M3代主要农艺性状的变异及多元分析

用60Co-γ射线诱变小麦连麦2号,对M3代292个穗行进行了主要农艺性状的变异及多元分析.结果表明:各性状的变异幅度是不同的,变异系数从大到小依次为:穗数＞千粒重＞穗长＞小穗数＞株高＞行粒重＞退化小穗数＞穗粒数＞穗粒重;变异率从大到小依次为:穗数＞千粒重＞株高=行粒重＞穗粒数＞穗长＞穗粒重＞小穗数＞退化小穗数.穗数、...     

Intergenotypic competition and shoot production in wheat plants

In field experiments, the competition among plants of two distinct wheat genotypes in binary mixtures, and among three genotypes being grown in adjacent rows was investigated. The competition greatly affected the over-ground dry weight, weight of stem and grain per plant. This effect was undercompensatory, the depression in poor competitor was higher than the enhancement of strong competitor for all these characteristics. From final components of grain yield per plant, the number of fertile stems and number of grains per ear were more affected than weight per grain. More expressively than weight of grain on the main-stem ear, the weight of grain per average secondary ear-bearing stem was affected by competition in binary mixture. The enhancement in standard height—a strongly competitive genotype— reached in binary mixture about 10% for this last characteristic in comparison with the value from the pure stand. Some morphological characteristics of plants being in relation with competition for grain yield per plant are discussed in these experiments.     

Regulation of internodal lenght by peroxidase enzymes in grain sorghum

Summary A relationship between height genes (dw locus) and perioxidase was demonstrated by extracting and determining peroxidase specific activity in internode tissue from different height isogenic lines of sorghum Sorghum bicolor (L.) Moench]. Tall plants (2 dwarf) had less peroxidase per gram tissue than their short counterparts (3 dwarf); their F₁ offspring internodes were closer but had more peroxidase than the tall parent. Peroxidase in the F₂ offspring was inversely related to their height and followed a simply-inherited pattern similar to that for height.Among different tissues analyzed, peroxidase concentration in roots was higher than in leaves and internodes, whole internode higher than in pith, and seed embryo higher than in endosperm. Peroxidase activity of nonviable seeds was negligible.Isoelectric focusing provided a more detailed peroxidase zymogram than did gel electrophoresis. Differences in peroxidase bands among tall and short parental plants, F₁ and F₂ segregating groups all appear to be reflected by intensity differences rather than by position or number of bands.Activities of nitrate reductase and acid phosphatase did not correlate with height. That finding provides a control and suggests that peroxidase activity is not associated with height by chance but may have a functional relationship.Contribution no. 1628-j, Dept. of Agronomy and no. 188-j, Dept. of Biochemistry, and no. 962-j, Dept. of Grain Science and Industry, Kansas State University, Kansas Agricultural Experiment Station, Manhattan, Kansas 66506.     

The effect of semi-dwarf genes on root system size in field-grown barley

Root system size (RSS) was measured in 12 diverse barley genotypes and 157 double-haploid lines (DHs), using electric capacitance. The parents of the DHs, Derkado and B83-12/21/5, carry different semi-dwarfing genes, sdw1 and ari-e.GP, respectively. Estimates of RSS were taken in the field thrice during plant development: stem elongation (RSS1), heading (RSS2) and grain filling (RSS3). The 12 barley genotypes were assessed over 3 years and at two or three locations each year; the DH mapping population was assessed at two locations in 2002. Among the 12 barley genotypes, those with the semi-dwarf genes had greater RSS values in all 3 years (28.9, 24.6 and 15.0% in years 1, 2 and 3, respectively) compared to non-semi-dwarf controls. The DH population showed transgressive segregation on both sides of the parent means, indicating polygenic control of RSS. Quantitative trait loci (QTLs) for RSS were found on five of the seven chromosomes: 1H, 3H, 4H, 5H and 7H and these were compared with previously mapped agronomic traits. The TotalRSS QTL on 3H was associated with sdw1 and QTLs for height, plant yield and plant weight. The RSS3 QTL on 5H was associated with ari-e.GP and QTLs for height, plant yield, plant weight, harvest index and tiller number. The RSS3 QTL on 7H was also associated with a TotalRSS QTL and QTLs for plant weight and harvest index. Other RSS QTLs were not associated with any other trait studied. RSS is considered to be a polygenic trait linked to important traits, in particular to yield. The study highlights the effects of semi-dwarfing genes and discusses the potential for breeding for root traits.     

Photosynthetic Characteristics of Non-Leaf Organs of Winter Wheat Cultivars Differing in Ear Type and their Relationship with Grain Mass Per Ear

Chlorophyll content, photosystem 2 functioning (F_v/F_m, F_v/F₀), activity of ribulose-1,5-bisphosphate carboxylase/oxygenase, and net photosynthetic rates (P _N) of flag leaf blade, sheath, peduncle, and ear organs were assessed in large-ear type (Pin 7) and small-ear type (ND93) wheat cultivars. Some differences were found in photosynthetic properties between different green plant parts, the values of all studied parameters in ear parts being higher in Pin7 than in ND93. Furthermore, ear surface areas and ear P _N in 26 wheat genotypes measured at anthesis showed highly significant positive correlation with grain mass per ear. Hence a greater capability of ear photosynthesis may result in a greater grain yield in large-ear type cultivars.     

Effect of Nitrogen and Water Stress on Photosynthesis and Nitrogen Content in Wheat

The relationships between photosynthesis, leaf nitrogen content and water stress were studied in ten genotypes of wheat differing in the presence of dwarfing genes. Net photosynthetic rate (P_N) was mostly higher at ear emergence stage than at anthesis stage. P_N decreased with water stress (leaf water potential from –2.0 to –2.5 MPa), and with reduced leaf N content in all genotypes studied. Among the various genotypes, single dwarf and wild types showed higher P_N rate and maintained higher leaf N content under different N doses and water supply as compared to the other types studied.     

Effects of cold on CO2 exchange in winter rape leaves

A viable wheat hybrid intermediate of the same height as the parents was obtained by crossing the female parent of tall variety NP4 with the male parent of the dwarf variety HD2160. Seeds of the hybrid and its parents were germinated and their growth pattern as well as the activities of peroxidase, indolyl-3-acetic acid oxidase and amylase in extracts made from them were studied at the early seedling stages i.e. up to 96 h.
A positive correlation existed between the length of the axis at the early seedling stage and at mature plant height as far as the parental varieties are concerned but no such correlation was observed with the hybrid. Growth of the hybrid seedlings was less than of its parents. Light appeared to stimulate the longitudinal growth of the axis to different extents in the parents and hybrid. Higher activities of peroxidase, indolyl-3-acetic acid oxidase and amylase were observed in the hybrid as compared to both of its parents. Lethal wheat hybrid also exhibits increased activities of amylase, indolyl-3-acetic acid oxidase and peroxidase. Therefore, it appears that seedling growth and enzyme activities at the seedling stage are not always correlated with hybrid vigour.     

Advanced backcross QTL analysis of a hard winter wheat × synthetic wheat population

Advanced backcross quantitative trait locus (AB-QTL) analysis was used to identify QTLs for yield and yield components in a backcross population developed from a cross between hard red winter wheat (Triticum aestivum L.) variety Karl 92 and the synthetic wheat line TA 4152-4. Phenotypic data were collected for agronomic traits including heading date, plant height, kernels per spike, kernel weight, tiller number, biomass, harvest index, test weight, grain yield, protein content, and kernel hardness on 190 BC₂F_2:4 lines grown in three replications in two Kansas environments. Severity of wheat soilborne mosaic virus (WSBMV) reaction was evaluated at one location. The population was genotyped using 151 microsatellite markers. Of the ten putative QTLs identified, seven were located on homoeologous group 2 and group 3 chromosomes. The favorable allele was contributed by cultivated parent Karl 92 at seven QTLs including a major one for WSBMV resistance, and by the synthetic parent at three QTLs: for grain hardness, kernels per spike, and tiller number. Mention of trade names or commercial products in this publication is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the U.S. Department of Agriculture.     

Heat Stress-Induced Cell Death, Changes in Antioxidants, Lipid Peroxidation, and Protease Activity in Wheat Leaves

Six wheat genotypes were evaluated for heat tolerance in terms of seedling growth, antioxidant response and cell death. Based on the heat susceptibility index (HSI), response of the genotypes varied from heat tolerant (Inqilab-91) to heat sensitive (Sitta) along with moderately tolerant (Nesser and Sarsabz) and sensitive (Fareed and FD-83). Heat stress-induced programmed cell death (probably necrosis) in wheat leaves was evident by DNA smear. MDA content increased above twofold in most of genotypes under heat stress, with the lowest increase in the heat-tolerant genotype Nesser. Catalase activity diminished under heat stress in all genotypes. Peroxidase, superoxide dismutase (SOD), protease, and ascorbate peroxidase (APX) activities increased under heat stress. Apparently, heat stress-induced reduction in catalase activity was compensated by a parallel increase in peroxidases to quench H₂O₂. Heat stress-induced decrease (%) in catalase and increase in protease activities showed significant positive correlations, whereas increase (%) in APX activity showed a significant negative correlation with HSI or relative heat tolerance of genotypes. All these correlations signify that catalase, protease and ascorbate peroxidase can be used efficiently as biochemical markers to assess the relative heat stress tolerance of wheat genotypes at the seedling stage. In conclusion, using a multiparametric approach involving morphophysiological and biochemical assays, the sensitivity of wheat genotypes to heat stress could be evaluated to a sufficient level of certainty at the seedling stage.     

Genetic dissection of grain yield in bread wheat. I. QTL analysis

Grain yield forms one of the key economic drivers behind a successful wheat (Triticum aestivum L.) cropping enterprise and is consequently a major target for wheat breeding programmes. However, due to its complex nature, little is known regarding the genetic control of grain yield. A doubled-haploid population, comprising 182 individuals, produced from a cross between two cultivars ‘Trident’ and ‘Molineux’, was used to construct a linkage map based largely on microsatellite molecular makers. ‘Trident’ represents a lineage of wheat varieties from southern Australia that has achieved consistently high relative grain yield across a range of environments. In comparison, ‘Molineux’ would be rated as a variety with low to moderate grain yield. The doubled-haploid population was grown from 2002 to 2005 in replicated field experiments at a range of environments across the southern Australian wheat belt. In total, grain yield data were recorded for the population at 18 site-year combinations. Grain yield components were also measured at three of these environments. Many loci previously found to be involved in the control of plant height, rust resistance and ear-emergence were found to influence grain yield and grain yield components in this population. An additional nine QTL, apparently unrelated to these traits, were also associated with grain yield. A QTL associated with grain yield on chromosome 1B, with no significant relationship with plant height, ear-emergence or rust resistance, was detected (LOD ≥2) at eight of the 18 environments. The mean yield, across 18 environments, of individuals carrying the ‘Molineux’ allele at the 1B locus was 4.8% higher than the mean grain yield of those lines carrying the ‘Trident’ allele at this locus. Another QTL identified on chromosome 4D was also associated with overall gain yield at six of the 18 environments. Of the nine grain yield QTL not shown to be associated with plant height, phenology or rust resistance, two were located near QTL associated with grain yield components. A third QTL, associated with grain yield components at each of the environments used for testing, was located on chromosome 7D. However, this QTL was not associated with grain yield at any of the environments. The implications of these findings on marker-assisted selection for grain yield are discussed.     

Combining ability analysis over F1-F5 generations in diallel crosses of bread wheat

Summary Combining ability studies for grain yield and its primary component traits in diallel crosses involving seven diverse wheat cultivars of bread wheat (Triticum aestivum L.) over generations F₁-F₅ are reported. The general and specific combining ability variances were significant in all generations for all the traits except specific combining ability variance for number of spikes per plant in the F₅. The ratio of general to specific combining ability variances was significant for all the traits except grain yield in all the generations. This indicated an equal role of additive and non-additive gene effects in the inheritance of grain yield, and the predominance of the former for its component traits. The presence of significant specific combining ability variances in even the advanced generations may be the result of an additive x additive type of epistasis or evolutionary divergence among progenies in the same parental array. The relative breeding values of the parental varieties, as indicated by their general combining ability effects, did not vary much over the generations. The cheap and reliable procedure observed for making the choice of parents, selecting hybrids and predicting advanced generation (F₅) bulk hybrid performance was the determination of breeding values of the parents on the relative performance of their F₂ progeny bulks.     

Single tester triple test cross analysis in spring wheat

Summary Two experiments, each including the same 30 homozygous varieties of spring wheat plus one separate tester variety, were conducted in order to detect epistasis and to test and estimate the additive and dominance components of genetic variation for five quantitative traits: final plant height, spike length, number of spikelets per spike, 100-kernel weight and grain yield per plant. Epistasis played a significant role in the control of 100-kernel weight and yield per plant. There was a gratifyingly good agreement between the two independent methods (2¯B₁i — ¯f_1i — ¯P_i and 2¯B_ci — ¯F_1i) used to test the presence of epistasis. In both experiments, there was a remarkably uniform high dominance ratio for most of the traits studied indicating that this test cross design is equally sensitive to both additive and dominance genetic variation.     

Carbon isotope discrimination and mineral composition of three organs in durum wheat genotypes grown under Mediterranean conditions

Carbon isotope discrimination (delta) has been proposed as a good criterion for transpiration efficiency and grain yield improvement. Its measurement, however, remains very expensive. Ash content (ma) has been proposed as an alternative criterion for delta in bread wheat and barley. The aims of this study were (i) to analyse the relationships between delta and mineral composition in different durum wheat plant parts and (ii) to compare the variation of these traits between landraces and improved varieties from different geographic origins. For this purpose, delta, ma, and composition in four minerals (K, Mg, P and Si) were assessed in flag leaves and awns at anthesis, and in mature grains of ten durum wheat genotypes grown under rainfed Mediterranean conditions. The three plant parts differed significantly for the measured traits. Significant correlations were noted between delta and ma in the flag leaf and in the grain. Silicon content in flag leaves and potassium content in awns were also positively related to delta of the considered plant part. The coefficient of correlation between delta and ma was generally higher than that observed between individual mineral content and delta, suggesting that ma is the better alternative criterion for delta. In addition, grain yield was related to grain delta and both ma and potassium content in awns. Harvest index was correlated with delta and ma of grain and flag leaf. These results emphasised that ma values in flag leaf and grain represent the efficiency of carbon partitioning to the grain. Improved varieties showed higher delta and ma values than landraces. Differences between Middle-East and West Mediterranean genotypes for the measured traits were also presented and discussed.