普通小麦与钩刺山羊草杂交F1的农艺性状及细胞遗传学的观察

为有效地利用钩刺山羊草（Ａｅｇｉｌｏｐｓ ｔｒｉｕｎｃｉａｌｉｓ Ｌ．）的抗白粉病基因对小麦（Ｔｒｉｔｉｃｕｍ ａｅｓｔｉｖｕｍ Ｌ．）进行遗传改良,了解两者杂交后杂种Ｆ１的遗传机制是十分必要的。对Ｆ１杂种的研究表明,二价体频率高于理论值,是分别存在于钩刺山羊草Ｃ和Ｕ基因组中的小麦５Ｂ染色体上Ｐｈ基因抑制因子联合作用的结果。以尾状山羊草（Ａｅｇｉｌｏｐｓ ｃａｕｄａｔａ Ｌ．）Ｃ基因组特异重复序列     

Microsatellite DNA polymorphism divergence in Triticum dicoccoides accessions highly resistant to yellow rust

 Stripe rust (yellow rust), caused by Puccinia striiformis f. sp. tritici, is one of the most important diseases of wheat throughout the world. Wild emmer wheat, Triticum dicoccoides, the progenitor of cultivated wheat, was found to be a valuable source for novel stripe-rust-resistance genes. The objective of the present study was to estimate the extent of genetic diversity among the wild emmer wheat accessions, previously identified as highly resistant to stripe rust, in order to select suitable parents for genetic-mapping studies. Twenty three wheat microsatellite (WMS) markers were used to detect DNA polymorphism among 21 accessions of T. dicoccoides, which included 19 resistant and two susceptible accessions originating mainly from the center of origin and diversity in the Upper Galilee and Hermon Mountain in northern Israel. In addition, two Triticum durum and one Triticum aestivum lines were also included in the analysis. The 23 WMS markers used were located on 23 chromosome arms, representing all 14 chromosomes of genomes A and B of wheat, and revealed a total of 230 alleles. The number of alleles ranged from 5 to 18, with an average of ten alleles per WMS. Genetic dissimilarity values between genotypes, calculated by the WMSderived data, were used to produce a dendrogram of the relationships among accessions using the unweighted pair-group method with arithmetic averages (UPGMA). The results showed that all of the wild emmer wheat accessions could be distinguished. Most of the resulting groups were strongly related to the ecogeographical origin of the accessions, indicating that the genetic diversity of T. dicoccoides is correlated with geographic distribution. The three major groups were the Rosh Pinna group (north of the Sea of Galilee), the Mount Hermon group (north of the Golan Heights) and Mount Kena’an group (Upper Galilee). The genetic similarity (GS) of the 21 T. dicoccoides accessions based on WMS results averaged 0.31. As expected, the T. durum and T. aestivum lines were grouped separately from the T. dicoccoides accessions. The results obtained suggest that a relatively small number of microsatellites can be used for the estimation of genetic diversity in wild material of T. dicoccoides. These results will be useful in the identification of suitable parents for the development of mapping populations for tagging yellow-rust resistance genes derived from T. dicoccoides. Furthermore, future work could test the adaptive evolutionary significance of microsatellites in natural populations of wild emmer wheat. Received: 8 August 1997 / Accepted: 25 August 1997     

Identification of RFLP markers linked to the cereal cyst nematode resistance gene (Cre) in wheat

The cereal cyst nematode (CCN) (Heterodera avenae Woll.) is an economically damaging pest of wheat in many of the worlds cereal growing areas. The development of CCN-resistant cultivars may be accelerated by the use of molecular markers. The Cre gene of the wheat line AUS 10894 confers resistance to CCN. Using a pair of near-isogenic lines (NILs) that should differ only in a small chromosome segment containing the Cre locus, we screened 58 group-2 probes and found two (Tag605 and CDO588) that detect polymorphism between the NILs. Nulli-tetrasomic and ditelosomic lines confirmed that the restriction fragment length polymorphism (RFLP) markers identified were derived from the long arm of wheat chromosome 2. Crosses between AUS 10894 and Spear and the NIL AP and its recurrent parent Prins were used to produce F₂ populations that gave the expected 31 segregation ratio for the resistance gene. Linkage analysis identified two RFLP markers flanking the resistance gene. Xglk605 and Xcdo588 mapped 7.3 cM (LOD=6.0) and 8.4 cM (LOD=6.7), respectively, from the Cre locus.     

几种农艺因素影响小麦籽粒蛋白质含量的数学模型研究

用二次回归旋转组合设计研究了基本亩数（X_1）、基苗氮肥（X_2）、孕穗期氮肥（X_3)、过磷酸钙（X_4）和氯化钾（X_5）用量对小麦籽粒蛋白质含量的影响．结果表明,X_4、X_1和X_2对蛋白质含量有显著作用,因素之间存在着复杂的互作效应．利用计算机模拟选优,获得了本试验条件下蛋白质含量大于13％的5个农艺因素组合方案,X_1=172.35～186.75万／ha;x_2=116.6～123.6kg／ha;x_3=33.75～39.15kg／ha;x_4=333.9～448.8kg／ha;x_5=190.65～233.10kg／ha．     

CO2浓度倍增对小麦叶绿体超微结构、超分子结构及光谱特性的影响

超薄切片及冰冻撕裂电镜观察、吸收光谱及77 K低温荧光发射光谱的测定结果表明:CO2浓度倍增对小麦( Triticum aestivum L.)叶绿体的超微、超分子结构及光谱特性的影响均为正效应.具体反映在:(1)小麦叶绿体中除了比对照积累有较多的淀粉粒外,其基粒和基质类囊体膜发育较好;(2)叶绿体的光合膜系,无论是垛叠和非垛叠膜区,其镶嵌于内质膜撕裂面(EFs和EFu)及原生质膜撕裂面(PFs和PFu)的功能蛋白粒均比其对照的发育良好,尤其PFs 与EFs面较为突出,即它们除了所含蛋白粒的密度较大外,在EFs面上有时还呈现出密集有序的阵列结构;(3)叶绿体整个吸收谱带,尤其红区和蓝区的主峰均较其对照有较大的光吸收,表明对光能的捕获能力明显高于对照;(4)无论是以436 nm还是以480nm波长激发的,其叶绿体的F684/F733 (PSⅡ/PSⅠ)的比值均较对照的高,表明CO2浓度倍增条件下生长的小麦叶片叶绿体的PSⅡ相对荧光强度有所增强,这与叶绿体的超微、超分子结构及吸收光谱的测定结果相一致.以上结果可为小麦在高CO2浓度下增产提供理论依据.     

基因枪介导小麦成熟胚遗传转化的影响因素

小麦成熟胚作为转化受体可克服小麦幼胚存在的受季节和幼胚发育阶段限制的缺点。以湖北省小麦品种‘鄂麦12’和模式品种‘Bobwhite’为材料,成熟胚为转化受体,优化基因枪转化法的轰击压力、轰击距离、选择剂等因素,建立以小麦成熟胚为转化受体的高效转化系统。结果表明:小麦成熟胚作为转化受体时,适宜轰击压力和轰击距离组合是900 psi、6 cm;成熟胚对选择剂G418的敏感性强于幼胚,轰击后需要延长恢复时间,选择剂G418的适合浓度为20～40 mg/L。在以上优化条件下小麦成熟胚转化频率达0.3%～0.9%,已初步建立基因枪介导的小麦成熟胚遗传转化系统。     

Characterization of HSP-70 cognate proteins from wheat

Summary Animal and plant cells contain a family of constitutively expressed HSP-70 cognate proteins that are localized in different subcellular locations and are presumed to play a role in protein folding and transport. Utilizing antibodies raised against the yeast endoplasmicreticulum-localized HSP-70 cognate termed BiP/GRP-78, as well as antibodies raised against the Escherichia coli HSP-70 protein DnaK, we have identified and characterized a large family of closely related proteins in wheat. One protein band of 78 kDa that is apparently closely related to yeast BiP was localized in the endoplasmic reticulum. This band cross-reacted with the yeast BiP but not with the DnaK-specific antibodies. The yeast BiP antibodies also recognized a cytoplasmic protein of 70 kDa that is probably related to the HSC-70 cognate proteins. These two proteins were further confirmed as HSP-70 cognates by their ability to bind to an ATP-agarose column. Probing of proteins from purified wheat mitochondrial preparations with the yeast BiP and DnaK-specific antibodies showed that this organelle contained a family of HSP-70-related proteins. The yeast BiP antibodies recognized two mitochondrial proteins of 60 and 58 kDa, but failed to detect any protein in the size rang of 70 to 80 kDa. However, the presence of immunologically distinct proteins of 90 and 78 kDa, as well as of lower molecular weight from this family in the mitochondria, was shown by probing with the DnaK-specific antibodies. A new protein of 30 kDa, cross-reacting with anti-yeast BiP antibodies, was detected only in developing seeds, close to their maturity. The evolution of HSP-70 cognate proteins in wheat as shown in this study is discussed.     

Effects of variations in soil water potential,depth of N placement,and cultivar on postanthesis N uptake by wheat

This study was conducted to investigate the influence of soil water potential, depth of N placement, timing, and cultivar on uptake of a small dose of labeled N applied after anthesis by wheat (Triticum aestivum L.) Understanding postanthesis N accumulation should allow better control of grain protein concentration through proper manipulation of inputs. Two hard, red spring-wheat cultivars were planted in early and late fall each yr of a 2-yr field experiment. Less than 1 kg N ha^–1 as K ¹⁵NO₃ was injected into the soil at two depths: shallow (0.05 to 0.08 m) and deep (0.15 to 0.18 m). In both years an irrigation was applied at anthesis, and injections of labeled N were timed 4, 12, and 20 days after anthesis (DAA). Soil water potential was estimated at the time of injection. Mean recovery of ¹⁵N in grain and straw was 57% of the ¹⁵N applied. Recovery did not differ between the high-protein (Yecora Rojo) and the low-protein (Anza or Yolo) cultivars. Mean recovery from deep placement was 60% versus only 54% from shallow placement (p < 0.01). Delaying the time of injection decreased mean recovery significantly from 58% at 4 DAA to 54% at 20 DAA. This decrease was most pronounced in the shallow placement, where soil drying was most severe. Regressions of recovery on soil water potential of individual cultivar x yr x planting x depth treatments were significant only under the driest conditions. Stepwise regression of ¹⁵N recovery on soil water potential and yield parameters using data from all treatments of both years resulted in an equation including soil water potential and N yield, with a multiple correlation coefficient of 0.64. The translocation of ¹⁵N to grain was higher (0.89) than the nitrogen harvest index (0.69), and showed a highly significant increase with increase in DAA. This experiment indicates that the N uptake capacity of wheat remains reasonably constant between 4 and 20 DAA unless soil drying is severe.