Utilization of alien genes to enhance Fusarium head blight resistance in wheat – A review

Fusarium head blight (FHB) is a destructive disease of wheat worldwide. Sources of resistance to FHB are limited in wheat. Search for novel sources of effective resistance to this disease has been an urgent need in wheat breeding. Fusarium head blight resistance has been identified in relatives of wheat. Alien chromatin carrying FHB resistance genes has been incorporated into wheat through chromosome addition, substitution, and translocation. Relatives of wheat demonstrate a great potential to enhance resistance of wheat to FHB.     

不同水分条件下小麦旗叶叶绿素a荧光参数与子粒灌浆速率

利用OS－30型叶绿素荧光分析仪研究水分胁迫对小麦旗叶叶绿素a荧光动力学参数的影响。结果表明，水分胁迫下旗叶的T1／2值减少，旗叶光系统Ⅱ（PSⅡ）原初光能转化效率（Fv/Fm)和潜在活性（Fv/Fo)降低，光合作用的潜在活力降低，这些参数下降影响了光合电子的传递和CO2同化的正常进行，表现在可变荧光淬灭速率减慢，可变荧光下降比值减小。同时还讨论了水分胁迫对灌浆速率的影响。     

砖筒仓充二氧化碳安全储麦技术研究

二氧化碳被导入一管道系统并使其在砖筒仓的粮堆内逐渐均匀分布，直到其在粮堆中的浓度达70％以上，试验其间通过该管道系统进行二氧化碳环流，经过14天停止操作，仓内粮堆中二氧化碳气体浓度保持35％以上，该气控方法储存小麦可达保鲜、无虫霉损害，安全储粮目的。     

Allelic variation at the dwarfing gene Rht8 locus and its significance in international breeding programmes

A microsatellite marker WMS261 developed at I.P.K., Gatersleben,Germany, co-segregates with the semi-dwarfing gene Rht8. Screens ofover 800 wheat varieties from 20 countries show 90% carry WMS-261alleles with 165, 174 or 192 base pairs (bp). The 192bp allele diagnosticof Rht8 occurs in most screened Southern European varieties. Anallele with 165 bp occurs in the majority of CIMMYT Mexican varieties andin most varieties bred in countries that utilize CIMMYT germplasm.Agronomic studies of single chromosome recombinant line mappingpopulations segregating for WMS 261 alleles with 165, 174 or 192 bp,show compared to the 174bp allele the 192bp allele reduces height byaround 8 cm and the 165 bp allele increases height by around 3cm. Theresults indicate the importance and widespread utilization of Rht8 asa dwarfing gene in southern Europe and suggest an adaptative significanceto the height promoting 165 bp allele in CIMMYT material.     

Isolation of wheat mutants with increased resistance to powdery mildew from small induced variant populations

Small variant wheat populations created by induced mutagenesis (n = 69) or adventitious regeneration (n = 66) were intensively screened for an altered response (compared to the parent variety ‘Guardian’) to the causal pathogen of powdery mildew in wheat, Blumeria graminis f. sp. tritici. Intensive field screening following natural infection of replicated plots of wheat lines over two years revealed a total of 13 mutants exhibiting significantly greater resistance than ‘Guardian’: eight from induced mutagenesis (11.6%) of the M2 population and five from adventitious regeneration (7.6%). Complete resistance was identified in two lines, (one (M66) developed following induced mutagenesis, and the other (SC240) by adventitious regeneration). The complete resistance in the induced mutant was stable over two generations and was associated with a high frequency of leaf flecking, and consequently a low grain yield. Resistance in SC240 proved to be unstable; SC240 exhibited complete resistance to powdery mildew in the SC₂ and SC₃ generations, but only 20% of the SC₄ plants were completely resistant, while the remainder were indistinguishable in mildew response to ‘Guardian’. The mildew response of all the SC₅ generation of SC240 was not significantly different from ‘Guardian’. Yield analysis of the thirteen mutants with increased resistance in the presence of powdery mildew indicated that eleven exhibitedgrain yields at least as high as that of ‘Guardian’, while the mutant M19 exhibited a yield significantly higher than that of ‘Guardian’. This revised version was published online in July 2006 with corrections to the Cover Date.     

不同浓度的镉离子(Cd2+)对小麦种子萌发的影响

以温麦6号为材料,探讨了不同浓度的重金属镉(Cd2 )对小麦种子萌发及根、芽生长的影响。结果表明:Cd2 对小麦种子萌发有较大的抑制作用;Cd2 浓度低于5mg/L时,能在一定程度上刺激小麦种子的萌发,小麦种子的发芽率和根数也略有增加;当Cd2 浓度大于5mg/L时,对小麦种子的萌发表现出明显的抑制效应,随Cd2 浓度的增加,幼根和幼芽的长度逐渐变短,芽重和根重明显下降,活力指数显著降低。此外,高浓度的Cd2 (50mg/L)引起小麦幼根根尖变褐,呈现中毒反应。     

Mapping QTLs for Yield Stability in Durum Wheat Grown under Different Water Regimes

Among the most important Mediterranean annual crops, durum wheat is widely grown in drought-prone areas. Therefore, improving water-use efficiency （WUE） of durum wheat represents a major breeding goal. IDu-WUE （Improving Durum wheat for Water Use Efficiency and yield stability through physiological and molecular approaches） is a collaborative project among public and private research centres in Italy, Spain and WANA （West Asia and North Africa） countries （Morocco, Tunisia, Syria and Lebanon） funded by the European Union aimed at investigating the genetic variation for WUE and yield stability in durum wheat grown in Mediterranean droughtprone areas. During the first year of the project, a number of morpho-physiological traits （e.g. early vigour, flowering time, leaf rolling, number of fertile tillers, etc.）, WUE, WUE-related traits （e.g. carbon isotope discrimination, canopy temperature, chlorophyll fluorescence, etc.）, yield and its components have been investigated in a RIL population （249 lines） and a collection of ca. 190 durum wheat accessions characterized by a high level of linkage disequilibrium （Maccaferri et al., 2005）,     

中国普通小麦生态区划及生态分类Ⅰ中国普通小麦生态区划

提出了由小麦气候生态区、地理生态区、栽培生态区及品种区域四级所构建的小麦生态区划体系。将中国普通小麦划分为５大气候生态区和２０个地理生态区，即：Ⅰ北方温带春麦气候生态区，包括东北、华北和西北３个春麦地理生态区；Ⅱ黄淮海暖温带冬麦气候生态区，包括海河流域、黄土高原、胶东沿海、华北平原、黄河中游丘陵川地和淮北平原６个冬麦地理生态区；Ⅲ南方亚热带（热带）秋（冬）播春麦气候生态区，包括长江中下游平原、秦巴山地、南方山地、四川盆地、云南高原、川贵高原６个秋播春麦地理生态区和华南冬播春麦地理生态区；Ⅳ新疆内陆冬春麦气候生态区，包括北疆春冬麦和南疆冬春麦两个地理生态区；Ⅴ青藏高原春冬麦气候生态区，包括青海春麦和西藏冬春麦两个地理生态区。     

冬小麦杂种后代灌浆速度的研究

为了研究冬小麦杂种后代灌浆速度遗传规律,我们从三个角度,十五种双亲灌速组合类型,分析了灌浆速度的遗传特点和遗传参数、不同双亲灌速组合类型对后代灌速的影响及其亲子关系密切程度;同时还对灌速进行了通径分析.结果表明,灌速为数量性状、不完全显性,呈现细胞核遗传和明显的“倾快”现象.后代灌速受双亲灌速共同作用,其中快亲起主导作用,慢亲也有一定的制约作用.双亲差异愈小,亲子关系愈密切;其中双亲灌速平均值与后代的关系皆比母与子、父与子密切:而父与子较母与子关系密切.灌速遗传力较高,在早代进行个体定向选择,可望获得较好的选择效果.欲提高灌速,要注重千粒重、功能叶面积、株粒重的选择,同时兼顾灌浆时间、株穗数、株粒数的选择,使其协调发展,综合提高.综合分析,以双亲灌速快,且灌速差异中等偏小,快速亲本作父本的组配形式为最好.     

Factors affecting haploid production in wheat using the Hordeum bulbosum system. 3. Post-fertilization effects on embryo survival

Summary An investigation was made of factors affecting the frequency of development of fertilized ovules following wheat x Hordeum bulbosum hybridizations. Seed survival, a term used here to represent the relationship between seed set and fertilization, was shown to vary between the wheat genotypes tested, but was unrelated to the crossability genes present within the wheat genotype. A high seed survival was obtained in crosses involving the variety TH3929 and the single chromosome substitution line, Chinese Spring (Hope 5B). Chinese Spring showed a poor seed survival. Some influence of the H. bulbosum genotype on seed survival was detected. The two environmental factors studied, namely the post-pollination application of gibberellic acid and the ambient temperature, were both shown to affect seed survival. The application of gibberellic acid immediately after pollination or 1 and 2 days after pollination improved seed survival, although the extent of the response was dependent upon the number and timing of the application(s). A genotype-dependent response to the ambient temperature was observed, TH3929 showing a slight but insignificant reduction and Chinese Spring a significant improvement in seed survival with an increase in temperature from 20°C to 26°C. The physiological processes which may be influenced by GA and the ambient temperature and may thereby affect seed survival are discussed.