玉米根系吸水细胞水平的杂种优势

在人工气候室水培条件下,以玉米(Zea mays L.)杂交种F₁代户单4号及其母本天四和父本478为材料,用细胞压力探针技术研究了正常供水和PEG-6000模拟–0.2 MPa水分胁迫条件下,玉米根皮层细胞水分关系参数的基因型差异。结果表明,根皮层细胞的直径、长度和体积均为F₁代>母本>父本;正常供水条件下3个玉米品种的根皮层细胞膨压均在0.6 MPa左右且品种间差异不显著,水分胁迫抑制了细胞的延伸生长且F₁代和母本的细胞膨压显著高于父本;根皮层细胞壁体积弹性模量均为父本>母本> F₁代,水分胁迫条件下的品种间差异显著;与正常供水条件相比,水分胁迫条件下细胞膨压显著降低,而弹性模量则大幅度提高;在两种水分条件下,水分跨细胞膜运转的半时间均为父本>母本>F₁代,且半时间在水分胁迫条件下均显著高于正常供水条件下;HgCl₂处理引起了半时间的延长,2-巯基乙醇则部分逆转了HgCl₂的效应;在两种水分条件下,根皮层细胞水导均为F₁代>母本>父本且品种间差异显著,水分胁迫则显著降低了细胞水导。试验证明杂交种F₁代的细胞水平根系吸水能力优于亲本,体现了杂种优势。     

Cytoplasmic male sterility with self-incompatibility,a novel approach to utilizing heterosis in rapeseed (<Emphasis Type="Italic">Brassica napus</Emphasis> L.)

The Polima cytoplasmic male sterility (CMS) system has been successfully used in three/two-line hybrid production in rapeseed (Brassica napus L.). However, the sterility of the Polima (pol) CMS lines is sensitive to temperature fluctuations. Also, traces of pollen can cause self-pollination within the CMS lines, which results in reduced levels of F₁ hybrid seed purity and leads to a significant yield loss. Self-incompatibility (SI) is another important approach for hybrid seed production in rapeseed. Despite having a wide range of restorers and being easily selected in a breeding program, SI system has some drawbacks. In this study, SI genes from a self-incompatible line of Brassica napus were transferred to a pol CMS line and S372A, a novel line of combined cytoplasmic male sterility with self-incompatibility was bred. Due to the SI genes, this line produced very few seeds when it was selfed at low temperature and no seeds at high temperature. This suggested that the line with CMS + SI had combined the advantages and overcome the disadvantages of both the pol CMS and SI systems. Furthermore, our results showed that most of the maintainers and all the restorers of the pol CMS system were also maintainers and restorers of the CMS + SI line, respectively. This indicates that the CMS + SI system can be easily used to establish three-line hybrids of rapeseed, and we believe this novel system could be extended to other species of Brassica.     

热带玉米Suwan1群体导入不同类型温带种质的遗传分析

采用不完全双列杂交法,分别将热带玉米Suwan1群体与我国温带玉米5大类群骨干自交系杂交,形成新的综合种,再与4个测验种杂交,组配36个杂交组合。通过2年1点的田间杂交组合8个表型(产量相关性状)评价,进行方差分析和配合力效应分析。方差分析表明,各杂交组合之间8个性状差异均达显著或极显著水平。产量一般配合力效应值大小为CML171/Suwan1Dan340/Suwan1P159/Suwan118599/Suwan1Chang7-2/Suwan1Mu6/Suwan1zheng58/Suwan191-95/Suwan1Mo17/Suwan1。根据联合产量分析,在36个组合中18599×Dan340/Suwan1和Dan340×CML171/Suwan1的杂种优势表现较强。由此,表现较好的杂种优势组型为PB、Tangsipingtou×Lvdahonggu/Suwan1(Reid/Suwan1)、Reid×Tangsipingtou/Suwan1、Reid×Lancaster/Suwan1,将Suwan1导入我国5大类群所形成的新种质对玉米的产量和其他性状的改良可以取得显著成效。     

杂交稻品质性状的遗传育种研究进展

杂交稻产量性状具有极大正向杂种优势的同时又与米质性状成负相关。杂交稻碾米品质、外观品质、蒸煮食味品质和营养品质等各米质性状之间存在诸多联系。这些品质性状由不育系和恢复系共同决定。因此,可采用籼粳混合进行杂交、亚种间的基因渗透、分子选育等选育组合方式,进行优质杂交稻不育系与恢复系组配优质杂交稻组合。     

Suwan1群体改良穗行选择效应研究分析

利用改良穗行选择法对热带玉米群体Suwan1改良两轮后,选用掖478、黄早四、Mo17、丹340、桂529作测验种为母本,Suwan1C0、Suwan1C1、Suwan1C2群体和墨黄9号为父本,按NCⅡ遗传交配设计组配20个测交组合,研究Suwan1改良效果。研究表明,经过两轮改良穗行选择后,Suwan1群体产量平均每轮增益6.22%;穗位变高,穗长、行粒数增加,平均每轮增益分别为5.11%、4.81%、2.25%;抽雄期变短,其他性状增益不大。产量一般配合力效应提高,但对产量特殊配合力改良效果不大。Suwan1群体与桂529有较强杂种优势,与丹340的杂种优势较弱,可用Suwan1及其自交系改良丹340等旅大红骨种质的抗病性和外观品质。     

化学杂交剂SQ 1诱导小麦雄性不育的效果及F1代杂种优势表现

为配制筛选山西省晋南麦区化杀杂种小麦强优势组合,选用20个小麦品种（系）,分为A、B两组,A组为山西省晋南麦区大面积推广品种10个,B组为自育且含异种属血统的品系10个,用化学杂交剂SQ1进行化杀。结果表明,在参试品种（系）生育时期处于Feeks 8.0～9.0时,喷施5.0 kg/hm的SQ1,诱导小麦雄性不育率达到98.76%以上;A组人工饱和授粉结实率和自然授粉结实率分别平均为70.87%和41.68%,B组分别为72.10%和57.31%,各材料间无显著差异,说明化学杂交剂 SQ1与参试小麦品种基因型间不存在互作效应。t检验结果表明,B组小区产量、穗粒数和公顷穗数的杂种优势与A组差异显著,杂种优势明显高于A组。评选出4个强优势组合,均含有异种属血统,其超标优势幅度达17.56%～43.13%,说明在利用化杀法时,选用较远缘的中间材料做化杀杂交亲本来提高杂种优势幅度是一条切实可行的途径。     

两系杂交小麦杂优3号的灌浆特性及杂种优势研究

为给低温敏感雄性不育（BNS）型两系杂交小麦的选育及高产栽培提供依据,对BNS型两系杂交小麦杂优3号的灌浆特性及其杂种优势进行了分析。结果表明,在整个灌浆过程中,杂优3号籽粒干重变化呈“S”曲线,干重增幅大于父本Bh001,具有明显的超高亲优势。与对照百农矮抗58相比,杂优3号在灌浆后期的优势较为明显。晚播可提高杂优3号最终千粒重和籽粒最大灌浆速率。杂优3号的籽粒灌浆速率呈正态变化曲线,在灌浆渐增期和快增期表现出明显的超高亲优势,在灌浆后期具有明显的超标优势。     

Heterosis effects in a black and white dairy cattle population under different production environments

The effect of the environmental level of production (ENV) on the expression of heterosis for 305-day milk, fat, protein, and fat plus protein (FP) yields, lactation average somatic cell score (LSCS), and age at first calving (AFC) was investigated in first lactation Black and White dairy cows in the Netherlands, and officially enrolled in the Dutch herd-book. Holstein Friesian (HF), Dutch Friesian (DF), and first generation (F₁) crosses obtained from the mating of HF sires and DF dams (HD) were involved in the study, and data from animals with a calving date between 1990 and 2000 were used. A total of 22,930 cows with production and AFC information distributed in 3549 herds and 11,055 cows with LSCS information distributed in 2071 herds, were available. Adjusted lactation yield of milk for each herd was obtained using a model that accounted for fixed effects of herd, year and month of calving, genotype, and AFC. The overall mean of all adjusted data was computed, and 3 ENV were defined on the basis of the overall mean ± 0.5 standard deviations. Once ENV was defined, traits were analysed with a model that included fixed effects of ENV, herd nested within ENV, AFC (only production traits and LSCS), year and month of calving, genotype, and the interaction between ENV and genotype. Least squares means for the interaction effect were used to estimate heterosis and to evaluate its magnitude across ENV. Holstein Friesian achieved higher productions than DF. First generation crosses showed productions close to HF, especially in the low ENV. Estimates of heterosis for yield traits ranged from 2.4% (milk) in the high to 5.3% (fat) in the low ENV, and reduced with increasing ENV. Estimates for LSCS and AFC were low, with the exception of LSCS in the high ENV. Results suggest that the highest non-additive genetic effects for yield traits and LSCS were expressed in the most stressful ENV, i.e., the low one for production and the high one for LSCS.     

Hybrid rice heterosis and genetic diversity of IRRI and Lao rice

Glutinous and non-glutinous rice hybrids derived from IRRI and Lao PDR rice germplasm were evaluated for yield heterosis and genetic diversity based on SSR markers. Pollen and spikelet fertilities of the hybrids showed absence of effective restorer and maintainer genes in the Lao varieties for WA-CMS cytoplasm. Positive heterosis over better or male parent (Lao varieties) was observed. Hybrids derived from an IRRIs TGMS line with Lao varieties showed a great potential in hybrid rice application. Genetic diversity among the rice lines was assessed by COP and SSR markers. Cluster analysis based on the molecular markers generated three parental groups in agreement with parental pedigree information. Significant linear relation was detected between yield heterosis and marker-based genetic distance of parents.     

甘蓝型油菜种子贮藏蛋白遗传距离与杂种优势关系研究

对38份不同生态区来源的甘蓝型油菜种质进行了贮藏蛋白电泳多态性分析,并对165个杂交组合农艺、品质性状表现及杂种优势与亲本贮藏蛋白距离进行相关分析,探讨了贮藏蛋白标记遗传距离辅助甘蓝型油菜农艺及品质杂种优势利用的可能性。结果表明：甘蓝型油菜种子贮藏蛋白多态性丰富;谷蛋白标记遗传距离（GDglu）、清蛋白标记遗传距离（GDalu ）与农艺、品质性状杂种后代表现及中亲优势存在不同程度的相关性,可以利这种相关性及谷蛋白标记遗传距离聚类辅助甘蓝型油菜杂交育种和品质育种的亲本选配,提高选配效率。