六倍体小黑麦和八倍体小偃麦杂交F_2的细胞学特性

以八倍体小偃麦(远中1号、远中3号和远中5号)与六倍体小黑麦杂交,对F2的形态学及细胞学特性进行了研究,以期为创造小麦-偃麦草-黑麦异位新种质奠定基础。结果表明,3个组合F2自交结实率分别为28.11%、41.11%、39.92%。不同组合根尖细胞染色体数目变化分别有8、12、29种类型,组合间染色体数目分别在46～58、49～60、34～64条变异。花粉母细胞减数分裂染色体行为异常,组合间平均每个细胞单价体数基本相当,分别为10.45、11.60和11.69。组合远中1号/兰考小黑麦和远中3号/兰考小黑麦中具多价体的细胞频率非常相近,分别为40.7%和39.2%,明显高于远中5号/兰考小黑麦组合中的频率(33.0%)。3个组合均出现较低频率的染色体桥,分别为6%、3%、3%。在二分孢子和四分孢子中普遍观察到微核。研究结果为揭示小麦-偃麦草-黑麦属间杂种染色体遗传特征提供了依据。     

中间偃麦草、长穗偃麦草及其杂交种抗旱性评价

测定了杂交种植物组织相对含水量、脯氨酸、叶绿素、可溶蛋白、丙二醛生理指标,利用主成分分析、隶属函数综合评价偃麦草属不同材料[中间偃麦草（Elytrigia intermedia）、长穗偃麦草（E.elongata）及其杂交种]的抗旱性。结果表明,5个单项生理指标可综合为3个相互独立的综合指标;正交杂种（E.intermedia×E.elongata）的抗旱综合值为 0.529,反交杂种（E.elongata×E.intermedia）为0.702,而其2个亲本中间偃麦草和长穗偃麦草仅为0.308和0.191,杂交种材料的抗旱能力远高于2个亲本,其中反交杂种的抗旱性最强。     

源于中间偃麦草的小麦新品系CH5026白粉病抗性的遗传

CH5026是衍生于八倍体小偃麦TAI7045的抗病新品系,它兼抗小麦的白粉病和条锈病。温室抗性评价结果显示,无论是苗期还是成株期,CH5026对白粉病菌系E09均表现为免疫,且具有与其抗性供体TAI7045及TAI7045的野生亲本中间偃麦草相似的白粉病抗性,且CH5026和TAI7045的小麦亲本均为中、高感,表明存在于CH5026的白粉病抗性来自中间偃麦草。为进一步明确其白粉病抗性的遗传规律,用高感品种(系)晋太170和CH5065分别与CH5026杂交、回交,将其F1,F2,BC1,F3群体及其双亲分别在太原温室用白粉病15号小种的E09菌系接种,并按单株调查其抗感分离之比。结果表明,F1对白粉病的感染分别为0或0;级。F2,BC1的群体中,其抗感分离分别符合3R∶1S和1R∶1S;而且在F3株系中,全抗∶抗感分离∶全感为1∶2∶1,说明衍生于TAI7045的抗病品系CH5026对白粉病的抗性受1对显性核基因控制。     

小麦-中间偃麦草异代换系的细胞学和SSR标记鉴定

中间偃麦草含有丰富的优良基因,在小麦的遗传改良中具有重要利用价值。对从八倍体小偃麦TAI-7045与普通小麦复合杂交后代中选育的小麦种质系CH-9916进行细胞学鉴定,其根尖细胞染色体数目为2n=42,为六倍体普通小麦,在苗期和成株期CH-9916对条锈病均表现免疫,中抗白粉病。通过SSR标记鉴定分析,其可能是由偃麦草的染色体代换了小麦的2D染色体。以上结果表明,种质系CH-9916可能是一个异代换系。     

秦王川灌区4个中型狼尾草的大田生产性能比较

通过田间试验, 比较了4个中型狼尾草(Pennisetum longissimum var. intermedium)野生驯化新品系在甘肃省永登县秦王川盐渍土区的物候期、生长速度、叶面积及分蘖数等性状指标的变化特征, 运用灰色系统理论对其生产性能进行了综合评价。结果表明, 品系1号、2号和3号出苗快, 成熟早, 生育天数147 d左右;品系4号出苗迟, 成熟晚, 生育天数160 d。1号中型狼尾草生长最快, 其株高在各个生育时期均显著高于其他3个材料(P＜0.05), 在开花期达最高(187.94 cm);品系3号生长较慢, 株高最矮(150.51 cm)。生育前中期, 参试材料单株叶面积、茎粗逐步增长, 抽穗期以后, 趋于平稳甚至有所下降, 品系1号、2号和4号变化一致且明显高于品系3号。品系2号分蘖能力最强, 其次是品系1号、3号和4号。综合评价认为, 中型狼尾草品系1号和2号生长速度快, 分蘖能力强, 产草量高, 成熟早, 综合生产性能优良, 适宜在永登县秦王川盐渍土区推广种植。     

3个抗条锈病小偃麦附加系中偃麦草染色体同源性鉴定

已经建立了3个抗条锈病小偃麦二体附加系,分别编号为 A1,A2和 A3。它们衍生于铭贤169与中4的杂交后代。铭贤169是一个普通小麦品种,它对我国现有全部条锈菌小种均高度感染。中4是人工合成的异源八倍体新种,含有全套小麦染色体和7对中间偃麦草染色体,对目前我国所有条锈菌小种均免疫或高抗。将铭贤169与中4杂交、用铭贤169回交、回交后代自交及抗病性鉴定得到了 A1,A2和 A3。为了搞清这3个附加系所附加染色的异同,将A1,A2和A3两两杂交,检查其 F_1植株减数分裂过程中染色体配对情况。在 A1×A2和 A2×A3的 F_1小孢子母细胞中出现了两个单价体染色体,在 A1×A3的 F_1中未发现单价体。这表明,A1与 A3所附加的是同一对中间偃麦草染色体,A2所附加的则是另一对。结论是,已经从中4鉴定出两种抗条锈病的中间偃麦草染色体,这两对染色体之间不具有同源性。     

中间偃麦草2Ai-2染色体DNA文库构建及特异性序列的克隆

 以二体异附加系Z2与其普通小麦亲本宛7107杂交F1的花粉母细胞为材料,用原位杂交方法确定其中的单价体为中间偃麦草2Ai-2染色体;在此基础上,以显微分离、回收、LA-PCR (Linker-adaptor PCR) 扩增了该条染色体,扩增产物长度在0.15～3 kb之间,主要分布在0.2～2 kb。以α-32P-dCTP标记的中间偃麦草的基因组DNA为探针,对LA-PCR扩增产物进行杂交,证实扩增产物来自中间偃麦草。将扩增片段纯化后连接到质粒载体pUC18上,构建了2Ai-2染色体DNA文库。该文库包含约     

Influence of sward condition on leaf tissue turnover in tall fescue and tall wheatgrass swards under continuous grazing

Two experiments were carried out on a tall fescue sward in two periods of spring 1994 and on a tall wheatgrass sward in autumn 2001 and spring 2003 to analyse the effect of sward surface height on herbage mass, leaf area index and leaf tissue flows under continuous grazing. The experiment on tall fescue was conducted without the application of fertilizer and the experiment with tall wheatgrass received 20 kg P ha^?1 and a total of 100 kg N ha^?1 in two equal dressings applied in March (autumn) and end of July (mid‐winter). Growth and senescence rates per unit area increased with increasing sward surface height of swards of both species. Maximum estimated lamina growth rates were 28 and 23 kg DM ha^?1 d^?1 for the tall fescue in early and late spring, respectively, and 25 and 36 kg DM ha^?1 d^?1 for tall wheatgrass in autumn and spring respectively. In the tall fescue sward, predicted average proportions of the current growth that were lost to senescence in early and late spring were around 0·40 for the sward surface heights of 30–80 mm, and increased to around 0·60 for sward surface heights over 130 mm. In the tall wheatgrass sward the corresponding values during spring increased from around 0·40 to 0·70 for sward surface heights between 80 and 130 mm. During autumn, senescence losses exceeded growth at sward surface heights above 90 mm. These results show the low efficiency of extensively managed grazing systems when compared with the high‐input systems based on perennial ryegrass.     

New insights into high-molecular-weight glutenin subunits and sub-genomes of the perennial crop Thinopyrum intermedium (Triticeae)

Intermediate wheatgrass (Thinopyrum intermedium) is a perennial crop that possesses desirable agronomic traits and provides environmental services, e.g., reducing soil erosion, nitrate leaching and inputs of energy and pesticide. Thus, intermediate wheatgrass is currently being domesticated as a perennial grain crop. However, the genetic information for molecular breeding is quite limited. Here we report a molecular analysis of high-molecular-weight glutenin subunits (HMW-GS) in intermediate wheatgrass using gene cloning and protein biochemistry. Five HMW-GS genes were isolated from individual intermediate wheatgrass plants: two x-type genes TiHGS1 and TiHGS4, and three y-type genes TiHGS2, TiHGS3 and TiHGS5. Among them, TiHGS5 was novel and possessed an additional cysteine residue at the N-terminal domain or repetitive domain. Sequence alignments showed that TiHGS1 and TiHGS2 genes shared high identities (>96%) with the Glu-1Dx and Glu-1Dy genes, respectively, in common wheat and Aegilops species, TiHGS3 with HMW-GS genes from Dasypyrum or Pseudoroegneria, and TiHGS4 and TiHGS5 with HMW-GS genes from Thinopyrum elongatum. This work provides substantial new insights into the gene compositions and protein profiles of HMW-GS in intermediate wheatgrass, and also gives evidence about the genome components of intermediate wheatgrass.     

天蓝冰草和八倍体小冰麦对大麦黄矮病毒抗性的研究

 本文对天蓝冰草的两个变种——蓝色变种、茸毛变种，6种八倍体小冰麦——中1、中2、中3、中4、中5（中4无芒）和苏联多年生小麦及其亲本进行了抗大麦黄矮病毒（BYDV）的研究。试验中使用了GAV、GPV和PAV等3个BYDV株系。试验分别在温室和田间进行。结果表明，天蓝冰草的两个变种对BYDV免疫；6种八倍体小冰麦对BYDV都有抗性，其中中3、中4、中5和苏联多年生小麦高抗BYDV，中1和中2的抗性低于上述4种。在相同条件下，八倍体小冰麦的亲本小麦对BYDV均无抗性，说明八倍体小冰麦的抗性均来自天蓝冰草。 由于已知八倍体小冰麦中1和中2带有基本相同的天蓝冰草染色体组，而中3、中4和中5带有相同的天蓝冰草染色体组，苏联多年生小麦携带的天蓝冰草染色体组既不同于中2的，也不同于中3的，可能是另一个天蓝冰草染色体组。所以可以推测天蓝冰草对BYDV的抗性是由分布在3个染色体组中的多基因控制的。但3个染色体组所决定的抗性水平不同，其中的两个染色体组，即中3、中4、中5所携带的天蓝冰草染色体组和苏联多年生所携带的天蓝冰草染色体组抗性水平较高。另一个染色体组，即中1和中2所携带的天蓝冰草染色体组抗性水平较低。